Table of contents

Using unsupported catalysts also improved stability during electrochemical reactions and high durability due to their non-corrosive component, carbon. Advanced mesoporous architectures were created in which the pore and metal composition are controlled at the nanoscale level. Rigid template-assisted synthesis, which makes periodic porosity in the solid, is used to create mesoporous platinum (Pt) and Pt bimetallic catalyst. The ability to control the composition, shape, and porous architecture of Pt and Pt bimetallic combinations, eliminating the carbon corrosion problem, improved the activity of the catalyst. Hence, 3D bicontinuous mesoporous silica KIT-6 and 2D mesoporous silica SBA-15 were synthesized. Ordered mesoporous silica prepared has uniform mesopores (7.9 and 7.3 nm for KIT-6 and SBA-15, respectively) and high specific surface areas 772 m².g⁻¹ (for KIT-6) and 943 m².g⁻¹ (for SBA-15). These rigid silica templates were employed to produce mesoporous metal particles for fuel cell electrocatalyst.

The prominent feature of Silicon nanotube MOSFET for using RADFET application is its high I_on/I_off ratio, minimal leakage current and less sensitive to short channel effects. Due to the above features the radiation behaviour of the device is studied to check for the applicability of a RADFET. Here both uniform and non-uniform irradiation characteristics are analysed. The focus of this study is on electrical characteristics and sensitivity, which is measured as a variation of threshold voltage of radiated and unirradiated device. It was found that on irradiation, the surface potential variation is high for 40 nm channel length hence the analysis is conducted for the same. It was proven to be successful, as the device achieves high I_on/I_off ratio of the order 10¹³ and a sensitivity of 2.26 mv Gy⁻¹. The obtained results are compared with DG RADFET and JL DG RADFET and it shows that Core gate Silicon nanotube RADFET has better electrical characteristics and sensitivity. The simulations are performed in Silvaco 3 D Atlas TCAD simulation software.

In this paper, a nanotube architecture of Junctionless FET (JLFET) is investigated wherein it is observed that the performance characteristics of JLFET are improved by introducing Dielectric Pockets into the device near the source-channel and channel-drain interfaces by coming up with a novel structure of nanotube junctionless FET (NTJLFET) called as Dielectric Pocket-NTJLFET (DP-NTJLFET). Using TCAD tool, the proposed DP-NTJLFET has been simulated for a channel length of 20 nm in order to consider and show the improvement in various short-channel effects. The inclusion of Dielectric Pockets into the device significantly reduced the OFF-state current, which eventually improved the current switching ratio (∼2600%) for a pocket length and thickness of 4 and 7 nm, respectively. Further, the proposed device exhibits an improved subthreshold swing characteristics and a better measure of DIBL (improved by ∼12%) for DP-NTJLFET as compared to the conventional NTJLFET. As a result of achieving low OFF-state current, the proposed DP-NTJLFET may be found suitable for the future low-power applications.

In this work, the performance of copper (Cu), dielectric inserted horizontal graphene nanoribbon (Di-HGNR) interconnect and dielectric inserted vertical graphene nanoribbon (Di-VGNR) interconnects are investigated using active shielding and passive shielding techniques. However, the analysis is carried out by adapting driver-interconnect-load system. This analysis considers the interconnect length from 500 to 2000 μm for 10 nm technology node. Further, the crosstalk induced effects on various interconnect structures are examined. It is envisaged that Di-VGNR exhibits lowest propagation delay compared to Cu and Di-HGNR. Further, the in-phase and out-phase crosstalk delay among the coupled interconnect lines is determined. It is investigated that active shielded Di-VGNR has least crosstalk induced delay compared to other interconnect structures considered in this study. Therefore, Di-VGNR interconnects outperforms Cu and Di-HGNR and are best suited for future VLSI interconnects.

In this paper we study the application of a single-CNTFET as power amplifier in the THz frequency range, using a CNTFET model, already proposed by us. We show that the device has, within stable condition, a Maximum Gain of at least 29 dB at frequencies below 30 GHz, decreasing to 20 dB at 800 GHz and reaching 18 dB at 1 THz. Through the analysis of a simple example, we show that it is possible to obtain a stable amplifier with tuned matching with a gain near the Maximum Gain at 1 THz. Finally we show that the matching of this device requires high ratio which could be hard to implement at 1 THz.

In this study; it is aimed to improve the rheological properties of Na-Bentonite water based drilling muds (WBDM) by graphene, graphene oxide (GO) and graphene oxide functionalized with gold nanoparticles (AuNPs/GO) at 0.0005–0.01 (% w/v) ratios. For this purpose, firstly; AuNPs, graphene, GO and AuNPs/GO were synthesized, and then characterized by SEM, TEM, EDX, RAIRS and XPS. Synthesized and characterized nanomaterials were added to WBDM at a rate of 0.0005% to 0.01% (w/v), and finally, rheological and filtration loss analyzes of water based drilling muds containing nanomaterials were carried out according to American Petroleum Institute Standards. As a result of this study, in which nanomaterials were used to improve the properties of water based drilling mud; plastic viscosity (PV), apparent viscosity (AV), yield point (YP), gel strength (10 s and 10 min), respectively; it was determined that it increased by 67%, 44%, 44%, 67% and 50%, and at the same time, the filtration loss value decreased by 14%.

Highlights

• AuNPs, Graphene and GO were synthesized seperatally, and then GO were functionalized with AuNPs

• Nanomaterials were characterized by SEM, TEM, EDX, RAIRS and XPS

• AuNPs/GO, which were tested for the first time in water based drilling mud

• It was concluded that all nanomaterials can be used as additives in water based drilling mud

High energy density combined with rapid mass transport is highly desired for carbon-based electrical double-layer capacitors. Here, multiscale porous carbon has been constructed by an efficient polymerization-pyrolysis strategy. The resorcinol-formaldehyde polymer anchored with Fe³⁺ is firstly prepared, and the in situ formed Fe₃O₄ nanoparticles act as mesoporous template during the pyrolysis process. The resultant hierarchically porous carbon achieves an extended surface area of 2260.3 m² g⁻¹ and wide pore size distributions including micro-, meso-, and macropores. The synergism of large surface area, high conductivity, and interconnected ion transport channels leads to superior energy storage performances of prepared multiscale porous carbon electrode. It delivers a high specific capacitance of 271.7 F g⁻¹ at 0.5 A g⁻¹ in KOH electrolyte, accompanied with a prominent capacitance retention of 88.5% when the current density is 10.0 A g⁻¹. Besides, the assembled symmetric supercapacitor using organic electrolyte exhibits a maximum energy density of 54.0 Wh kg⁻¹ at the power density of 750.0 W kg⁻¹, as well as the superior cyclic stability with a capacitance retention of 88.2% after 10000 cycles.

A 3D petal-like Transition metal phosphide (TMP) doped with Zn²⁺ on nickel foam was developed by a low-temperature phosphating approach for effective oxygen evolution reaction (OER), premised on the idea of developing TMP for high-efficiency water splitting. The loading of Zn²⁺ on the P surface raises the electron density, which is favorable for capturing protons in the water during the reaction, accelerating the electron transport rate, and accelerating the OER process. At the same time, we evaluated the optimal Zn²⁺ content ratio. When the Zn²⁺ to Fe³⁺ molar ratio is 0.5, the NiFeZnP-0.5/NF exhibits the best OER performance. The catalyst displays an overpotential of ∼136 mV at 10 mA cm⁻², ∼201 mV at 100 mA cm⁻², Tafel slope of 35 mV dec⁻¹ in 1 M KOH solution, and remains stable over 6 h. The C_dl of the NiFeZnP-0.5/NF electrode is 4.3 mF cm⁻², which increased by 5 times than the NiFeZn-LDHs/NF. Electrocatalysts' high performance is due to their superior electrical conductivity and synergy with the substrate. Our research provides a realistic solution in the field of electrocatalysis.

Effects of doping cadmium atoms on the electronic and optical properties of (n, 0) zigzag single-wall carbon nanotubes SWCNTs are investigated by density functional theory DFT, using ultrasoft pseudopotential generalized gradient approximation GGA approach. The electronic and optical properties of the zigzag SWCNTs are susceptible and dependent on the n index and diameter of the tube; these features have only in nanotubes. Adding any impurity to the Zigzag SWCNTs must be caused to change in properties. The density of states for Cd-doped and un-doped SWCNTs increases with an increase in n index because of overlap valence and conduction bands in all situations (small bandgap). All samples have metallic characteristics. Almost all absorption and reflectivity spectra peaks are produced in the UV range. It can be noted that the peaks of the un-doped samples are higher than that of Cd-doped. Consequently, the material's ability to store energy and photon absorption for un-doped nanotubes is larger than Cd-doped zigzag SWCNTs. These results are achieved in the figures of dielectric functions.

In this paper, a novel approximate Full Adder cell is presented which is based on the combination of standard CMOS logic (S-CMOS) and pass transistor logic (PTL) styles. The carbon nanotube field-effect transistor (CNFET) technology is used to simulate and implement the proposed cell. Comprehensive simulations at various power supplies, output loads, and ambient temperatures are conducted using the HSPICE tool. According to simulation results, its delay, power-delay product (PDP), energy-delay product (EDP), and normalized energy-delay-area product (NEDAP) improve by 18%, 10%, 39%, and 15% compared with the best existing design. The effects of diameter variations of carbon nanotubes (CNTs) on the functionality of the circuits are studied by Monte Carlo (MC) transient analysis. Simulation results confirm that the proposed cell is resistant to the process variations. At the application level, all circuits are employed in image blending to assess their efficacy in terms of peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) index criteria using the MATLAB tool.

The chemical approach synthesis of graphene oxide easily with four to five layers. Pt nanoparticles are anchored to graphene oxides by lattice defects and functional groups like carbonyls, epoxides, hydroxyls, etc. The electrical characteristics of these graphene oxide sheets were enhanced. The shape and physical properties of these graphene materials are comparable, but because of variations in the number of oxygen functions, significant changes in electrical conductivity, graphitization, and stability have been seen.

The manuscript focused on the concept of junction-less tunnel transistor to suggest and simulate the dielectric modulated double cavity nanotube TFET as a biosensor. The proposed biosensor worked as a label-free detector about dielectric constant (K) and charge density (ρ). In this, for neutral biomolecules (streptavidin and 3-aminopropyl-triethoxysilane (APTES)) and charged biomolecule (deoxyribonucleic acid (DNA)) are used for detection by the proposed sensor. The inner and outer cavities of the nanotube biosensor provide a large area for the stabilization of biomolecules and use the benefits of material solubility. The sensing capability of the proposed device investigates various DC performance parameters for the different dielectric biomolecules and charge densities. Further, the effect of substitution of SiO₂ gate insulating layer by HfO₂ also studies the sensing capability of the proposed biosensor. Moreover, a relative study of the biosensor for the presence and absence of inner and outer nanogap cavities performs in terms of different DC components to analyze the sensitivity variation.

Pyrolysis of metal-organic framework (MOF) to generate nanostructured carbon-based materials is a potential approach for creating carbon-based materials. The development of a cobalt-based MOF (Co-MOF-74) and its application to oxygen electrocatalysis are described in this study. In alkaline media, the as-obtained Co-PC-400 catalyst displayed superior catalytic performance with the onset potential (E_o = 0.90 V vs. RHE) and more outstanding durability than a Pt/C (20 wt%). Results show that the catalyst has a lot of promise in fuel cells. The Co-MOF successfully catalyzes due to its more significant onset potential, higher current density, and extended durability.

In this work, thin films of cobalt oxides (CoO₂, Co₃O₄) were prepared using the electrochemical method on the pencil graphite and indium tin oxide surfaces. The substrate effect in the production of both oxides has been studied in detail. While Co₃O₄ accumulates on the pencil graphite's surface, CoO₂ formation was observed on the indium tin oxide. The characterization of the cobalt oxides was carried out using the X-ray diffraction, Atomic force microscope, and Scanning electron microscope. In this context, the cobalt oxide crystal structure in the range of (−1.0 V)–(+1.9 V) was synthesized on different substrates and at extremely low temperatures (20 °C to 25 °C), using the cyclic voltammetry method, which is a simple one-stage way. Calculated band gap value for ITO/CoO₂ as 2.5 eV shows a potential use of this electrode in solar cell applications.

Today, electromagnetic waves play an important role in our lives. These waves are used for radio and television communications, telecommunication networks and all wireless communications. Therefore, due to the widespread use of electromagnetic waves in the GHz range for mobile phones, national networks, radar systems, etc., it is a serious threat to human health. The presence of different electromagnetic fields and waves in space also causes improper operation or reduced efficiency in electrical and electronic circuits and components. Therefore, the issue of designing appropriate and efficient filters to protect electrical devices and maintain human health is doubly important. In this research, metamaterials and their application as absorbers in frequency-selective surfaces are studied. The design and development process of the frequency-selective surfaces based on graphite are presented in two steps. Finally, the performance of proposed structures with one and two hexagonal loops are discussed. The obtained results demonstrate that the base element consists of a hexagonal loop made of graphite filters the frequency band of 8–12 GHz. However, the base element consists of two hexagonal loops is able to filter the frequency band of 4–12 GHz. In fact, the proposed structure with two hexagonal lopps has filtered a larger frequency band.

In this study, the voltage and frequency dependencies of dielectric properties of Al/Polyacrylonitrile (PAN)/n˗Si/Al metal/polymer/semiconductor (MPS) were analyzed. To determine the dielectric characteristics, capacitance˗voltage (C–V) and conductance˗voltage (G–V) of Al/PAN/n˗Si/Al were measured depending on the frequency and bias voltage ranges in 10 kHz–1 MHz and ±5 V at room temperature. Using the C–V and G–V measurements, dielectric parameters; ε', ε'', and tan δ, M'and M'', were evaluated depending on voltage and frequency. As the frequency increased, ε' and ε'' decreased, while peaks related to the relaxation mechanism were observed in M'' and tan δ. The ε' values at 10 kHz and 1 MHz are 15.2 and 4.58 for 1 V, respectively. Relaxation times were calculated using the peaks in the M''˗f plot and it was seen that the relaxation time decreased as the bias voltage increased. Relaxation mechanism is related to non˗Debye relaxation in PAN/n–Si structure. The existence of relaxation peaks in M'' curves showed that the studied material is an ionic conductor.

Herein, we report the methods adopted for the syntheses of nano-scale CeO₂ materials by wet chemical routes (solution combustion, hydrothermal, and precipitation by NH₄OH and mixture of NH₄HCO₃ and NH₄OH) and their experimental results supported by TG-DTA, XRD, FESEM-EDX, FT-IR, and NIR characterization techniques. The nano-scale CeO₂ materials were obtained through wet chemical and simple calcination methods in a single-step process. The thermal (TG) profile of precursor salt ((NH₄)₂Ce(NO₃)₆) reveals ∼72% of weight loss in the temperature ranges from 30 °C to 800 °C, whereas the different as-obtained CeO₂ materials showed ∼3%–13% of weight loss indicating the formation of cubic nanostructured CeO₂ materials, as evidenced from XRD patterns. All the pure materials obtained in a single step crystallized in cubic nanostructured CeO₂ phase with the average crystalline sizes in the range of 3–28 nm. The morphology of the combustion obtained CeO₂ materials exhibits spherical-shaped fine particles with moderate agglomeration. The as-obtained CeO₂ materials can be used in the solar reflective and color pigment applications as it shows remarkably high NIR reflectance in the NIR region, 750–2500 nm compared to other binary oxides. The visual appearance of the as-obtained CeO₂ powder was pale yellow color and varied with the preparation conditions. The FT-IR band observed at ∼490–534 cm⁻¹ for all the as-obtained CeO₂ materials confirming the metal oxide network, Ce–O.

Space charge accumulation in the polypropylene will accelerate the aging of the material and lead to the degradation of its insulation performance. In the work, space charge distribution, current conduction characteristics, thermally stimulated depolarization current (TSDC) and surface potential decay (SPD) characteristics of polypropylene (PP) under strong electric field are measured and analyzed, and the bulk trap and surface trap parameters are extracted. Further, the charge transport model of PP is established to study the charge dynamic transport physical processes and characteristics under strong electric field. The experimental results show that the charge accumulation amount in PP under the action of negative polarity electric field is higher than that of positive polarity electric field, about one order of magnitude. and the corresponding trap energy levels are 0.84 eV and 0.81 eV, which both belong to deep traps. There are two obvious charge density peaks on the PP surface, which are 2.60 × 10²⁰·eV⁻¹·m⁻³ and 3.66 × 10²⁰·eV⁻¹·m⁻³, respectively, and the corresponding surface trap energy levels are 0.86 eV and 0.97 eV. The simulation results show that with the extension of the applied voltage time, the injected charges by the electrode gradually migrate to the bulk of the material and eventually the positive and negative charges are offset at the middle position. The local electric field caused by the accumulation of interfacial charges will weaken the original electric field, while the local electric field caused by the accumulation of the bulk charges will strengthen the original electric field, resulting in the distortion of the internal electric field.

A comprehensive review of the features of silicon carbide (SiC) and various methods of deposition of gate oxides are presented in this report. The SiC material, which is mostly employed as base component in metal oxide semiconductor field effect transistors (MOSFETs) is very promising; for its high voltage, high power, high temperature and high breakdown field properties. These features have made it very attractive for use in power electronic devices over its counterparts in the field. Despite these great features, and the significant progress recorded in the past few years regarding the quality of the material, there are still some issues relating to optimization of the surface and interface processing. This review discusses the effect of surface modification and treatment as a means of enhancing the electrical performance of the SiC-based MOSFETs. It also identifies the challenges of controlling the density of dielectric/SiC interface trap that is needed to improve the values of mobility channels, and several oxidation techniques that could be used to surmount the structural limitations presently encountered by the SiO₂/SiC system. Reliability as a significant aspect of electronic structures was also discussed with much emphasis on causes of their breakdown and possible solutions, especially in high thermal applications.

The component produced with best surface quality increases the life time of the product and with the objective of attaining it AA7050 hybrid composites was processed using the Electric Discharge Machining (EDM) technique. The composites with varying weight percentage of reinforced particles (2, 4, 6, 8 wt%) was manufactured using the stir casting technique, with SiC and Al₂O₃ as reinforcement and uniform dispersion of particles were confirmed through SEM with EDS mapping. EDM experimentations were conducted on the composites by varying the Pulse on Time (Ton), Current (A), Powder concentration and reinforcement weight percentage and the experimental runs were being designed using the Taguchi mixed orthogonal array, Whereas Material Removal Rate (MRR), Tool Wear Rate (TWR), Surface Roughness (Ra) and Machined Surface Hardness (MSH) were recorded as response. The MRR increased from 38.72 mg min⁻¹ to 73.67 mg min⁻¹ when SiC particles were incorporated in the dielectric fluid attributed to the fact that generated heat was uniformly dispersed throughout the machined surface due to the low thermal conductivity of SiC particles. When powder particles were incorporated, TWR for composites machined with 2 wt percent reinforcing materials increased substantially to 32.61 mg min⁻¹. Because of the high density of SiC particles (4.36 g cm⁻³), the scattered particles settled throughout the machined surface, reducing the surface quality by 12% with particle inclusion. Black spots, remelted particles, globules and micro pits are some of the textures observed on the machined surface morphology.

A detailed investigation was done on Li and Nb modified Bi_0.5Na_0.5TiO₃ (BNT) thin films where structural, dielectric, ferroelectric and electrocaloric properties were studied. All thin films were synthesized using pulsed laser deposition. Structural investigation revealed that addition of Li and Nb do not alter the parent rhombohedral structure and all compositions were observed to have rhombohedral structure. However Ferroelectric and dielectric analysis clearly revealed that addition of Li and Nb affect the Ferroelectric (FE) -Antiferroelectric (AFE) phase transition temperature (T_d, depolarization temperature) and bring it down towards the room temperature and consequently a mixed phase of FE and AFE was observed near room temperature for composition x = 0.06. A sudden change in polarization in x = 0.06 composition with increasing temperature, subsequently leading to significantly high (∂P/∂T)_E along with FE-AFE transition contributed to large electrocaloric (ΔT) = − 4.32 K in composition x = 0.06 ∼ 35 °C.

The objective of this study is to report the results of dielectric properties and dielectric breakdown strength (DBS) of PbO-B₂O₃-SeO₂:Ho₂O₃ (PBSH) glass ceramics as functions of Au₂O₃ content and to correlate the results with spectroscopic properties. PBSH glass ceramics with traces of Au₂O₃ were fabricated and characterized with different techniques that include positron annihilation spectroscopy (PAS). Several dielectric parameters and DBS were studied as functions of Au₂O₃ concentration. Observed increase of ε' with Au₂O₃ content was attributed to a hike in the space charge polarization (scp) due to the increased concentration of structural imperfections. Dipolar relaxation phenomenon exhibited by electric moduli was analyzed using Cole-Cole plots. σ_ac(a c, conductivity) showed an increasing tendency with Au₂O₃ content. Such increase was attributed to the polaronic exchange between two structural groups of SeO₂. Inferences drawn from dielectric and DBS studies were found to be in agreement with different spectroscopic properties of these glass ceramics.

Single-phase spinel ferrites with formula of Ni_1−xCo_xFe₂O₄ where x values are varying from 0 to 1 with 0.25 steps were synthesized by sol-gel technique. Microstructure, cation distribution, valence state of iron and dielectric properties have been discussed. From the deconvoluted Raman spectra the positions of five Raman modes and intensity variation was calculated. Cationic arrangement in A and B sites was estimated from deconvoluted Raman peaks. The characteristic magnetic patterns of ferrites were given by room temperature Mossbauer spectra. Parameters like isomer shift, hyperfine magnetic field, quadrupole shift were estimated for all ferrites after fitting Mossbauer spectra. From XPS (X-ray Photoelectron Spectroscopy) analysis +3 ionic state for iron was found. Dielectric parameters were also studied for ferrites at room temperature. NiFe₂O₄ and Ni_0.75Co_0.25Fe₂O₄ had high values of dielectric permittivity, AC conductivity and loss tangent. The ferrite Ni_0.5Co_0.5Fe₂O₄ showed very less dielectric constant and conductivity values and dielectric loss resonance peak was around 1 kHz.

Adsorption is one of the most favored procedures in advanced wastewater treatment. Magnetic hybrid materials have a great adsorption performance and excellent reusability in the industry. For this reason, the amazing roles of Sm₂O₃ doping on Co₃O₄/PANI hybrid nanocomposite materials were studied. Co₃O₄ nanoparticles were synthesized using the thermal decomposition technique where Sm₂O₃ doped Co₃O₄/ PANI hybrid nanocomposite materials were prepared via in situ oxidative polymerization. The X-ray analysis, technique results confirm the successful formation of neat Co₃O₄ nanoparticles with cubic phase and its presence in emeraldine phase of PANI matrix. X-ray reveals that the crystallinity of hybrid nanocomposite materials increases with increasing Sm₂O₃ doping ratio. HRTEM showed polycrystalline structure of Co₃O₄ nanoparticles and that the doped Sm₂O₃ was well incorporated and dispersed within the PANI matrix. The surfaces topography was studied by FESEM. UV–Vis diffuse reflectance spectrum revealed two characteristic bands of PANI that are shifted towards higher wavelengths with Sm₂O₃ doping ratio. The calculated indirect energy gaps were found to decrease from 2.83–2.56 eV which indicates a good response of the hybrid nanocomposite materials to the effect of the UV absorption. The magnetic properties of the investigated samples are measured by VSM. Ms was found to decrease with increasing Sm₂O₃, while Hc increase with Sm₂O₃ ratio which will hinder the domain walls motion. Adsorptive removal of chlorpyrifos could be ascribed as pseudo-second ordered and Langmuir model. The maximum adsorptive capacity was 36.9, 47.11, 63.8, and 83.03, 96.73 mg/g for PANI, Co₃O₄/PANI, Co₃O₄/PANI-2 wt% Sm₂O₃, Co₃O₄/PANI/−4 wt% Sm₂O₃, and Co₃O₄/PANI-6 wt% Sm₂O₃hybridnanocomposite materials, respectively.

The work aims to investigate the magnetocaloric effect (an eco-friendly and energy-efficient cooling technique) of Te doped nanosized dysprosia, which could be used as the best alternative for conventional chlorofluorocarbons based refrigeration systems. In this present work, Te doped nano-sized dysprosia (TNSD) is synthesized using the sol-gel technique. The particle characteristics and magnetocaloric properties of TNSD were investigated. The change in lattice parameters of NSD concerning doping of TNSD is analyzed by using Rietveld refinement. The synthesized nanoparticles were observed to be spherical and monophasic with a Ia-3 structure. At low temperature, the sample exhibited a non-saturated magnetic behavior due to the co-existence of ferromagnetic and antiferromagnetic phases, while at high temperature it exhibited a paramagnetic nature. The maximum entropy change of TNSD at a magnetic field of 50 kOe was found to be 30.6 JKg⁻¹K⁻¹. The significant magnetic transitions at low temperature and large magnetic entropy change make TNSD suitable material as a refrigerant for cryo-cooling systems.

The present manuscript explores the impact of Dy doping in the Tantalum based bismuth layer structured ferroelectrics with chemical composition of Sr(Bi_1-xDy_x)₂Ta₂O₉ (where x = 0.00, 0.025, 0.05, 0.075 and 0.10) prepared by mixed oxide process. X-ray diffraction study of all the ceramics implement orthorhombic phase without any secondary phase. The polycrystalline nature and grain distribution in the materials is studied from scanning electron microscope study. The temperature dependent dielectric performance of Dy doped SBT ceramics at selected frequencies indicates diffuse order phase transitions with reduction in transition temperature (T_c) and relative permittivity with doping level. The residual polarization and coercive field reduce with doping. The conduction mechanism was analyzed using the frequency and temperature domain impedance spectroscopy for all composition. The electrical contribution from both grains and grain boundary in the doped ceramics in the reported temperatures is confirmed from the Nyquist plots and the non-Debye type of relaxation mechanism is manifested from the depressed semicircles in all of them. The ac conductivities variation with frequencies at the studied temperatures follow Jonscher's power law and the fitting parameters suggests that the conduction mechanism obey the correlated barrier-hopping model.

Reported work demonstrates the application of common source amplifier circuit using the proposed Gate Stack based Gate All Around Dopingless Nanowire Field Effect Transistor (GS GAA DL NW—FET) structure. Primarily, impact of the gate stack (GS) technique on the conventional Gate All Around Dopingless Nanowire Field Effect Transistor (GAA DL NW—FET) structure is explored. The proposed FET structure resulted in excellent electrostatic control over the channel by incorporating the advantages of GAA architectures and dopingless technique. As transfer characteristics of conventional GAA DL NW—FET have been enhanced with gate stack (SiO₂ + high k) technique when employed at dielectric region. A contrast is drawn between both structures in terms of analog parametric analysis which resulted in improved I_ON of 30.6 (μA), reduced I_OFF of 10⁻⁷ (μA) and enhanced I_ON/I_OFF of 6.7 × 10⁷. Linearity analysis were made to examine the distortion less digital communication and a fair comparison is depicted between the structures. CS amplifier circuit application with proposed GS GAA DL NW—FET resulted in improved V_OUT with 15.2 dB of gain when compared with GAA DL NW—FET based CS amplifier which stood at 13.9 dB which proves the promising candidature for forthcoming nanoscale circuit applications.

In this work, we studied the temperature dependences of endurance cycling properties on atomic layer deposition (ALD) HfAlO metal-ferroelectric-metal (MFM) capacitor in the range from 25 °C, 40 °C, 50 °C and 75 °C. Base on experiment results, it is found the reduction percentage of the ferroelectric memory window (2Pr) from 6.5 μC cm⁻² (25 °C) to 6.3 μC cm⁻² (75 °C) is only 3%, indicating that the ferroelectric HfAlO film has a robust operating temperature stability. The excellent high temperature endurance properties show around 30% of the original 2Pr value (6.3 μC cm⁻²) can be held after being fatigued up to 10⁸ endurance cycles at 75 °C without breakdown. Additionally, using Arrhenius plot fitting (ln(J/E) vs 1/kT) before and after endurance cycles was extracted the changes of trapping energy level to better understand the relationship between leakage current, oxygen vacancies or defects tapping of polarization-switching behavior in HfAlO ferroelectric film.

In this research, nanostructured zinc oxide (ZnO) and hafnium-doped zinc oxide ceramic samples were prepared by the sol-gel technique. ZnO and at%0.5 hafnium-doped ZnO (HZO) nanostructures and their surface morphologies were studied by XRD and FESEM. AC electrical properties (capacitance, conductance, and complex impedance) of ZnO and HZO were studied by impedance analyzer with the frequency range from 20 Hz to 1.5 MHz and temperature range from 300 K to 500 K. General analysis of AC electrical measurements showed that both samples had different equivalent circuit diagrams. The best-fitted equivalent circuit diagram for ZnO was "R(RC)(RC)" at all temperatures. The circuit diagram for HZO was "R(RCPE)" at 300 K, 350 K, and 400 K temperatures and "R(RCPE)(RCPE)" at 450 K, and 500 K temperatures. Negative temperature coefficient of resistance (NTCR), non-Debye behavior, and multiple relaxation times were observed.

In this study, a simple, rapid, and environmentally friendly green approach for synthesizing Fe₃O₄ and Fe₃O₄/chitosan nanoparticles with various concentrations was developed. The nanoparticles had a spherical shape with a cubic inverse spinel structure. The functionalization of the Fe₃O₄ nanoparticles using chitosan increased the crystallite size of the nanoparticles from 7.2 to 7.8 nm. The Fourier transform infrared spectra of the Fe₃O₄/chitosan nanoparticles showed the existence of the characteristic peaks of chitosan in addition to a peak at 578 cm⁻¹, which corresponds to the stretching of the Fe−O group. The UV-visible spectra demonstrated a wide absorption band with the appearance of small peaks of chitosan absorption at 205 and 215 nm. The saturation magnetization of the Fe₃O₄ was 54.1 emu g⁻¹. The surface plasmon resonance (SPR) measurements showed an enhancement in the SPR angle as the ratio of chitosan to Fe₃O₄ increased, wherein the angle shift from 0.17° to 1.91°. The chitosan covering the Fe₃O₄ nanoparticle surface caused the refractive index to change, which increased the SPR angle shift. The obtained results indicated that the SPR properties of the Fe₃O₄ nanoparticles were significantly improved by modification with chitosan. These results also indicated that the use of chitosan in Fe₃O₄ nanoparticles can enhance SPR properties, which has potential for future SPR-based sensor applications.

Direct semiconductor wafer bonding is a versatile fabrication scheme for high-performance optoelectronic devices. In the present study, the influence of oxygen concentration in the bonding ambient on the electrical conductance at directly bonded Si/Si interfaces is experimentally investigated in relation to interfacial oxidation. The interfacial electrical conductivity is observed higher for lower oxygen concentration at each bonding temperature in the range of 200 °C–400 °C. Ohmic contact characteristics are found attainable in the bonded interfaces by proper choice of bonding conditions. To support the electrical conductance trend, an X-ray photoelectron spectroscopy analysis confirms the extent of interfacial oxidation to be higher for lower oxygen concentration and higher bonding temperature. In addition, solar cell fabrication and operation with a current path through the bonded interface are demonstrated by using the bonding method in a low oxygen concentration ambient. The energy conversion efficiency of the bonded cell is observed comparable to that of an unbonded reference, to thus verify the suitability of the bonding scheme for device applications.

As a crucial substrate material for optoelectronic materials, sapphire has important applications in both military and civilian fields. In order to achieve the final processing quality of sapphire substrate materials, double-sided chemical mechanical polishing (DS-CMP) is a necessary process, which is also a guarantee for the preparation of high-end LED chips. In this article, the sapphire DS-CMP processing plan based on the Box-Behnken design is obtained and experimented. Then, a hybrid approach of response surface method (RSM) and support vector machines (SVM) algorithm is established as the material removal rate (MRR) prediction model for sapphire DS-CMP. Furthermore, the material removal process of sapphire DS-CMP, the influence of response variables on the MRR of sapphire DS-CMP, and the prediction results of RSM-SVM on sapphire DS-CMP are analyzed respectively. From the experimental results, the maximum MRR obtained is 387.59 nm min⁻¹, which is more than 6 times the reported MRR of single-sided CMP under similar process parameters. The mean square error of predicted value through RSM-SVM is basically around ±10% of the experimental value, which possess satisfied validity for the MRR prediction of sapphire DS-CMP. Finally, both top and bottom surface quality of sapphire wafers after DS-CMP processing was investigated.

Along with the remarkable growth in the complexity of semiconductor fabrication technology, chemical mechanical planarization (CMP) has evolved and become progressively more sophisticated over the years, enabling the implementation of novel integration schemes. This paper discusses current research and development trends in one specific aspect of the CMP technology, namely, ceria particle usage for advanced technology nodes and provides some perspectives on how to improve CMP performance metrics of the current ceria abrasives and ceria-based CMP slurries and move forward to the next phase.

For improving the three-dimensional structure of phase-change memory devices, Ovonic threshold switch devices have received renewed attention as selectors owing to a simple production process, good scalability, and excellent performance. It can replace transistors and diodes in the available technology. In this article, we studied the GeSe-based chemical mechanical polishing process. The different concentrations of hydrogen peroxide and lysine interacting with GeSe in chemical mechanical polishing were investigated. Material characterization was performed by scanning electron microscopy and atomic force microscopy. In addition, the reaction mechanism in the chemical mechanical polishing process was analyzed by electrochemical experiments and X-ray photoelectron spectroscopy.

A dilute chlorine trifluoride gas at less than 1% was possible for the cleaning of a silicon carbide chemical vapor deposition (CVD) reactor. For 20 min, the chlorine trifluoride gas at the concentrations of 0.5%–1% in ambient nitrogen at atmospheric pressure could detach the 30 μm-thick particle-type polycrystalline silicon carbide CVD film from the susceptor which had a coating film made of a purified pyrolytic carbon (PPyC). While the PPyC film had some damage due to the shallow fluorine diffusion, it could be recovered without any pit formation by annealing in ambient nitrogen containing a trace amount of oxygen at atmospheric pressure for 10 min at the temperature of 845 °C.

The stability of the cobalt surface after the CMP process is crucial to prevent the corrosion of the surface during the wafer transfer step. The stability of the Co-BTA complex is investigated in this work by using various experimental and surface analysis techniques. The higher inhibition efficiency of the Co-BTA complex observed at pH 7 was further investigated, and a more passive Co surface was observed during the de-ionized water (DIW) rinsing step. The low stability of the Co-BTA complex in the presence of slurry additives was confirmed from the accelerated oxidative dissolution of the Co surface compared to the adsorption of BTA. Ex-situ electrochemical impedance spectroscopy (EIS) was further performed to analyze the stability of the Co-BTA complex to confirm the passivation of Co during the DIW rinsing step. The corrosion resistance of the Co surface during the rinsing step is further enhanced by reducing the dissolved oxygen content.

Silicon is used for consumable parts in reactive ion etching (RIE) equipment because it generates fewer particles, which decrease the yield, than other materials. Polycrystalline silicon is usually used for top electrodes, especially in high-aspect-ratio RIE, to increase the wafer's self-bias. In this study, the relationships among the crystal orientation of the polycrystalline silicon used in RIE equipment, grain size, grain boundary length, etch rate, and surface roughness were investigated. The grain size and the etch rate decreased as the percentage of Si(111) in the polycrystalline silicon increased. The grain size and etch rate for 47% Si(111) decreased to 66.4% and 84.7%, respectively, compared with 8% Si(111). Moreover, the grain boundary length and surface roughness increased as the percentage of Si(111) increased. The grain boundary length and surface roughness for 47% Si(111) increased by 1.8 and 19.6 times, respectively, compared with 8% Si(111). Therefore, as the percentage of Si(111) increased, the grain size and etch rate decreased, whereas the grain boundary length and surface roughness increased.

This study investigates the effect of chemical mechanical planarization (CMP) processing parameters such as platen velocity, the concentration of the oxidizer and abrasive nanoparticle, slurry pH and surfactant types on the surface roughness of cadmium zinc telluride (CdZnTe) substrate. It was found that these parameters have a significant effect on the quality of the polished surfaces. It was found that lower platen velocity, lesser concentration of abrasive particles, basic slurry pH, and addition of anionic surfactant (SDS) into the CMP slurry solution showed improved surface planarity. Optical Surface Profiler and atomic force microscopy (AFM) techniques were used to monitor the surface topography before and after polishing. A notable root-mean-square surface roughness, (R_q), ∼0.9 nm, has been obtained on the polished CdZnTe (CZT) surface over a scan area of 481 × 361 μm² under the optimized conditions of 60 rpm relative velocity, slurry pH of 9, 3.75 vol% of oxidizer (H₂O₂) and 1.25 wt% of abrasive (SiO₂ nanoparticle). A probable mechanism of the present CMP surface planarization of CZT substrate has been proposed. Unlike the conventional surface planarization processes, which involve two-step lapping followed by CMP for the CZT surfaces, we have developed a single step CMP process to obtain good surface planarity.

In silicon heterojunction (SHJ) solar cells, a wide bandgap material with a high work function is widely used as the hole extraction pathway to attain high efficiency. We introduced a molybdenum oxide (MoO_x) film as an effective hole-transfer layer in carrier selective contact (CSC) solar cells by virtue of its wide bandgap along with high work function. The passivation characteristics, optical and electrical properties of MoO_x films were investigated by differing thickness and work function. The combination of 6 nm hydrogenated intrinsic amorphous silicon (a-Si:H(i)) and 7 nm thermally evaporated MoO_x passivation layers provides excellent passivation properties, reduces carrier recombination, and improves the cell performance. The synthesized CSC solar cells showed promising results, with an open-circuit voltage (V_oc) of 708 mV, short-circuit current (J_sc) = 37.38 mA cm⁻², fill factor (FF) = 74.59%, and efficiency (η) = 19.75%. To justify the obtained result, an AFORS HET simulation was conducted based on the experimental results. The high work function and wide bandgap MoO_x/c-Si(n) interface developed a considerable built-in potential and suppressed the electron–hole pair recombination mechanism. The CSC solar cell's simulated performance was enhanced from 1.62 to 23.32% by varying the MoO_x work function (Φ_MoOx) from 4.5 to 5.7 eV.

Al₀₅Ga_0.5N/n-Al_0.3Ga_0.7N/AlN metal-oxide-semiconductor heterostructure field- effect transistors (MOS-HFETs), grown on a SiC substrate, with composite Al₂O₃/in situ SiN passivation and Al₂O₃ gate dielectric are investigated. 20 nm thick high-k Al₂O₃ was deposited by using a non-vacuum ultrasonic spray pyrolysis deposition (USPD) method. Comparative studies between an in situ SiN-passivated Schottky-gate HFET (sample A) and a composite Al₂O₃/SiN-passivated MOS-HFET were made. Besides, electrical and deep-UV sensing characteristics for devices with different gate-drain separations (L_GD) of 6 μm and 14 μm were also studied. Improved device performances have been obtained for the present sample B (A) with L_GD = 6/14 μm separately, including maximum drain-source current density (I_{DS, max}) of 634.4/463.1 (421.8/301.1) mA mm⁻¹, maximum extrinsic transconductance (g_{m, max}) of 25.2/17.9 (19.1/15.2) mS mm⁻¹, on/off-current ratio (I_on/I_off) of 7.4 × 10⁷/5.4 × 10⁷ (4.5 × 10⁵/5.4 × 10⁴), two-terminal off-state gate-drain breakdown voltage (BV_GD) of −420/−480 (−320/−390) V, and three-terminal on-state drain-source breakdown voltage (BV_DS) of 310/380 (220/300) V at 300 K. Superior spectral responsivity (SR) of 885.6 A W⁻¹ under 250 nm deep-UV radiation has also been achieved for the present MOS-HFET.

For the first time, this research focuses on the inexpensive technique of synthesis of Cu₂In₂O₅ thin films using intermixing of Cu and In layers, deposited using radio frequency (RF) magnetron sputtering technique. Further, structural, morphological, and optical characterization of Cu₂In₂O₅ thin films have been carried out. The layered films were sputtered using Cu and In targets. The layered structure was subjected to post-deposition annealing at temperatures varying from 700 °C to 1000 °C in a constant oxygen ambiance for five hours. Decomposition of the single-phase Cu₂In₂O₅ takes place at 1000 °C, resulting in the appearance of CuO, In₂O₃, and Cu₂O as decomposition products. Descriptive analysis of the formation of the aforementioned products have been included. However, single-phase Cu₂In₂O₅ thin films were obtained at a post-annealing temperature of 900 °C. The oxidation states of In and Cu have been studied through XPS analysis. Full width half maximum (FWHM), peak positions, satellite peak positions, and their respective binding energies have been elucidated through XPS analysis. An increase in the grain size from 36.8 nm to 115.8 nm with an increase in the annealing temperature from 700 °C to 1000 °C, was noticed from the FESEM images. Optical studies were performed on all the annealed films in the 200–2000 nm wavelength range. The bandgap was in the range of 2.88 to 3.46 eV for the films annealed between 700 °C to 900 °C. The refractive index of the single-phase Cu₂In₂O₅ thin film was obtained to be 1.51.

This study investigates the gate degradation mechanisms of Schottky p-GaN gate HEMTs systemically. The constant gate bias stress is applied to investigate the gate breakdown. Schottky p-GaN Gate HEMTs show a shorter gate lifetime as gate bias increases. The gate leakage current after gate breakdown shows a resistance-like characteristic. The equivalent circuit has been proposed to discuss the gate breakdown mechanisms. When applying a high gate bias for a long time, the high electric field will damage the p-GaN gate and passivation interface and generate the percolation path. The primary gate breakdown happens between the gate and source and results in a resistance-like I–V characteristic.

A high frequency enhancement mode quaternary InAlGaN/GaN MIS-HEMT with recessed gate (L_g = 150 nm) processed using an oxygen-based digital etching technique is presented. The digital etching was performed by cyclic ICP oxygen treatment to oxidize InAlGaN barrier and HCl wet etching to remove the oxidized layer. In this study, we have demonstrated that the threshold voltage can be adjusted in a wide-range from depletion mode to enhancement mode with a nanometer scale gate for high frequency InAlGaN/GaN MIS-HEMT using the digital etching technique. In addition, the etch rate can be controlled from 0.7 nm/cycle to 3.6 nm cycle⁻¹ with RF bias power changing from 0 W to 40 W with high flexibility in etching rate. The post-etching surface roughness was around 0.12 nm regardless of the ICP oxidation voltage. The enhancement-mode InAlGaN quaternary GaN HEMT with maximum drain current of 955 mA mm⁻¹, gm⁻¹ peak of 440 mS mm⁻¹, V_th of 0.2 V, and f_t/f_max of 45/59 GHz were achieved using the digital etching for the gate recess structure.

The solid-state incandescent LED is a device that emits broad spectrum warm white light from nano-resistors through black body radiation. Previously, the steady state operation of the device was simulated with the finite element analysis method using COMSOL Multiphysics, while the light intensity distribution was separately simulated using MATLAB. There were limitations in these studies with respect to the number, size variation, and distribution of nano-resistors. In this paper, a new Python framework is developed to simulate light emission and perform COMSOL simulations for the same nano-resistor arrangement. The framework circumvents the nano-resistor count and distribution limitations in previous studies. This allows for more sophisticated simulations of many more nano-resistors than previously possible, and investigation into the effect of nano-resistor count on the device.

In this work, a high reverse blocking voltage (BV_R) p-GaN gate high electron mobility transistor with field control drain (FCD-HEMT) has been proposed and fabricated. The FCD-HEMT features the field control drain (FCD), consisting of electrically shorted Ohmic contact structure and p-GaN cap. In the OFF-state, the 2-Dimensional Electron Gas (2DEG) channel is cut off due to the p-GaN cap introduced field control, which provides FCD-HEMT with reverse blocking capability. In the ON-state, the re-formed 2DEG channel offers a non-potential barrier pathway for electrons transfer from source to drain and ensures a low resistance of the FCD-HEMT. The fabricated device exhibits 1400 V forward breakdown voltage (BV_F) and −1240 V reverse breakdown voltage (BV_R), 12.7 mΩ·cm² low specific ON-resistance, and 188 mA mm⁻¹ max drain current while maintaining normally-OFF capability. These results demonstrate the great potential of FCD-HEMTs in 1200 V-class power applications.

As electronic systems become larger and more complex, detection of the most vulnerable regions (MVR) to radiation exposure becomes more difficult and time consuming. We present a heuristic approach where the mechanical and thermal aspects of devices are exploited to quickly identify MVRs. Our approach involves the topological mapping of two device conditions. The first condition identifies regions with the highest mechanical strain or density of defects and interfaces via thermal wave probing and phase analysis. The second condition identifies regions with high electrical field. It is hypothesized that the region with the highest thermal wave penetration resistance and electrical field will exhibit the highest sensitivity to incoming radiation for single events and potentially, total ionizing dose. Our approach implements a simplistic design that improves analysis time by ∼2–3 orders of magnitude over current radiation sensitivity mapping methods. The design is demonstrated on the well-studied operational amplifier LM124, which shows agreement with the literature in identifying sensitive transistors–QR1, Q9, and Q18–with relatively high phase percentile values (>70%) and ΔT percentiles (>50%), satisfying conditions for elevated radiation susceptibility. This is followed by experimental results on a static random access memory (HM-6504) and a Xilinx Artix-7 35 T system on a chip.

In this paper, we demonstrate a high voltage normally-off p-GaN gate high-electron-mobility-transistor (HEMT) to realize the compatible high threshold voltage (V_TH) and high drain current (I_D) performance. With the optimization of the epitaxial structure, the presented device shows a significantly improved V_TH. Meanwhile, by using the high-quality ALD-Al₂O₃ passivation layer, the high I_D is also realized in the device because of the access region resistance reduction. Supported by the device fabrication, the p-GaN gate HEMT delivers a V_TH = 3.2 V measured by linear extrapolation, a relatively large saturation I_D (I_{D_SAT}) of 246 mA mm⁻¹, and a high breakdown voltage (BV) of 1830 V at 1 mA mm⁻¹. Among various p-GaN gate HEMTs with the I_{D_SAT} over 200 mA mm⁻¹, the fabricated p-GaN gate HEMT has a competitive V_TH. The results suggest that the proposed device could be a promising candidate in high V_TH and I_D power electronics.

The effect of hydrogen on GaN metal-oxide-semiconductor (MOS) capacitors with Al₂O₃, HfO₂, or Hf_0.57Si_0.43O_x gate dielectrics was studied using capacitance–voltage (C–V) measurements. Hydrogen exposure shifted all the C–V curves toward the negative bias direction, and the hydrogen response of the devices was reversible. When the hydrogen-containing ambient atmosphere was changed to N₂, the C–V characteristics were found to gradually revert to the initial values in N₂. Application of a reverse gate bias accelerated the reversion compared with that in the absence of a bias, indicating that hydrogen was absorbed into the dielectric (Hf_0.57Si_0.43O_x) as positive mobile charges. This result is consistent with the direction of the shift of the C–V curves; positively charged hydrogen absorbed into a dielectric can cause a flatband voltage shift. The hydrogen-induced shift of the C–V curves varied depending on the dielectric. MOS devices with HfO₂-based high-k dielectrics were found to have approximately two to four times more incorporated charges than devices with Al₂O₃. Under the hypothesis that oxygen vacancies (V_Os) trap hydrogen, the obtained results imply that the number of V_Os in HfO₂-based high-k dielectrics is much larger than that in Al₂O₃-based dielectrics.

In this study, ZrO₂/Cu/ZrO₂ nanostructured multilayers were constructed on glass substrates with diverse Cu interlayer thickness (5–25 nm) employing pulsed DC magnetron sputtering. The optoelectronics and structural characteristics of the multilayer films were reconnoitered. The calculated band gap was reduced from 3.0 to 2.68 eV as the Cu interlayer thickness increased from 0 to 25 nm. The refractive index and coefficient of extinction of ZrO₂/Cu/ZrO₂ multilayers increased with increasing the Cu interlayer thickness in the visible range. The resistivity recorded a value of 7.29 × 10⁻³ Ω·cm for ZrO₂/Cu (5 nm)/ZrO₂ multilayer film while recorded a value of 3.3 × 10⁻³ Ω·cm for ZrO₂/Cu (20 nm)/ZrO₂ multilayer film. It was found that the ZrO₂/Cu (20 nm)/ZrO₂ multilayer film verified the greatest figure of merit value of 3.35 × 10⁻³ Ω⁻¹ which signifying the best multilayer for transparent conductive film. The ZrO₂/Cu/ZrO₂ multilayer can be involved as a platform for designing optical nano-filter for molecular detections. For this purpose, the quality factor Q, the FWHM and the optical response of the proposed (ZrO₂/Cu/ZrO₂)³/Cu_mid/(ZrO₂/Cu/ZrO₂)³ optical nano-filter model were calculated theoretically using finite difference time domain technique (FDTD). The quality factor and FWHM of the proposed model recorded values of 5800 and 0.23 nm respectively for Cu mid thickness of 30 nm, which can be potentially engaged as optical nano- filter for molecular detections.

A series of Ca(PO₃)₂ phosphors mono-doped with Eu³⁺ were successfully synthesized by the conventional high-temperature solid-phase method. Rietveld correction of the X-ray diffraction shows that Eu³⁺ ions occupy Ca²⁺ positions in the Ca(PO₃)₂ lattice and have no effect on the matrix structure. In this work, the self-reduction of Eu³⁺ was observed and verified by photoluminescence (PL), excitation spectroscopy (PLE) and X-ray photoelectron spectroscopy (XPS). Under excitation at 238 nm, Ca(PO₃)₂: Eu exhibits a broad blue Eu²⁺ emission band in addition to the usual orange-red emission of Eu³⁺. The fact that europium ions exist in divalent and trivalent forms was further confirmed, and the corresponding mechanism of the anomalous reduction of Eu³⁺ to Eu²⁺ is discussed. On this basis, the effect of Eu concentration on the structure and luminescence properties of Ca(PO₃)₂ phosphor was investigated in detail. The luminescence of the phosphor exhibited bright tunable emission in the blue region and the red region. These results indicate that the Ca(PO₃)₂: Eu phosphors have potential applications as a n-UV convertible phosphor for light-emitting diodes.

Fluorescence materials have been widely employed for anti-counterfeiting techniques owing to their high-throughput, facile identification, and simplicity of production. However, the stability of the materials is a prerequisite for their subsequent application. Here, a series of SrGa₁₂O₁₉: Sm³⁺, Tb³⁺ phosphors with multi-color luminescence are obtained successfully by the traditional solid-state method. These Sm³⁺/Tb³⁺ co-doped phosphors emit green, orange and yellow-green under the excitation of 254 nm, 365 nm, and 254 nm+365 nm UV lamps, respectively. After removal of the UV lamp, the green long persistent luminescence (LPL) phenomenon is exhibited and then vanished 15 s later. The dynamic PL and LPL are associated with the interaction between PL and trapping centers. Notably, as-obtained phosphors show excellent stability against both air water resistance, and high temperature, which features the as-obtained phosphors a great application potential in high-level anti-counterfeiting with high stability.

Synthesis of nanoparticles (NPs) is gaining attention as a cost-effective and environmentally acceptable alternative to remove the pollutant by facile photocatalysis process. Role of hydrothermal treatment on Zinc-oxide (ZnO) nanostructures were investigated using non-ionic surfactant diethanolamine (DEA). Further, in order to investigate the effect of DEA on morphological variation different concentration of DEA was used. The samples were thoroughly characterized by XRD, Rietveld analysis, FESEM and TEM to get insight idea about the ZnO structural and morphological properties. Moreover, XPS spectra reveal the variation of surface oxygen defects as hydrothermal treatment induced more defects to ZnO material. BET measurement reveals the alteration of surface area and pore size of ZnO sample. The surface defect-states (mostly oxygen vacancies) of the catalyst nanoparticles can influence the photocatalytic degradation of MB dye activated by ZnO nanoflowers via a non-radiative energy transfer pathway. A steady-state photoluminescence analysis validated the photoinduced electron transport from ZnO to MB dye. Steady state photoluminesence emission spectra established one to one correlation between the defects and colour emission from ZnO. Spectral overlap between donor (ZnO) to acceptor (MB dye) also enhanced greatly after hydrothermal treatment ascribing more Förster resonance energy transfer (FRET) which accelerates photocatalytic degradation efficiency of methylene blue (MB) dye under UV light irradiation. The defect-engineered ZnO nanoparticles synthesized through facile hydrothermal treatment led to an efficient decolourization of MB dye which was strengthened by FRET based on a correlation of photocatalytic degradation and defect mediated colour emission.

Oxygen reduction reaction is considered as the "bottleneck" of the energy storage and utilization reactions, and understanding the specific reaction pathway and mechanism are essential in designing new catalysts. Interdigitated array electrodes are special electrochemical tool for in situ measurements and have the advantage of high collection efficiency and high sensitivity, which could be utilized for the detection of the reaction intermediate. Here in this work, the nonprecious metal catalyst Ni was studied in situ towards the ORR catalytic activity with IDA electrodes. Through the electrodeposition method, the Ni catalyst was conducted with the IDA electrodes successfully. The generator-collector mode of IDA electrodes was applied so as to carry out ORR and have the reaction intermediate H₂O₂ being detected simultaneously. It was observed that the average electron transfer number of Ni-catalyzed ORR is about 3, and it various with the change of applied potential and the surface state of catalyst. The H₂O₂ production changes between 40% and 75%, reflecting the possible reaction pathway at different status. After being annealed with different temperatures, the overall catalytic current enhanced with the increase of temperature, while the average electron transfer number declined.

Herein, we report the successful detection of ethanol among the variety of Volatile Organic Compounds (VOCs) namely isopropanol, toluene and acetone at room temperature (RT) via a thermally reduced graphene oxide (T-RGO) based sensor. T-RGO material was prepared by the thermal reduction of graphene oxide (GO) at 250 °C for 20 min. The properties of as-synthesized T-RGO were elucidated by X-ray diffraction, Raman spectroscopy, FT-IR spectroscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy and Brunauer–Emmett–Teller (BET) techniques. The BET analysis of T-RGO revealed the mesoporous structure with specific surface area of 86.21 m² g⁻¹. The proposed T-RGO sensor was exposed to various ethanol concentrations ranging from 5 to 100 ppm and the sensor exhibited maximum response (15%) towards 100 ppm of ethanol at RT. The high sensitivity, fast response (3 s)/recovery time (6 s) and excellent repeatability of ethanol, suggest its good selectivity over other tested VOCs. The optimum operating temperature of the sensor was found to be RT (28 °C). Upon exposure to different relative humidity (RH) levels, the ethanol sensing response was found to vary only by 1.5% from 33% to 83% RH, indicating low dependence of humidity on the sensor performance. In addition, the sensor displayed efficient long-term stability towards ethanol at RT.