Materials Research Express

In this research TiO₂, SnO₂ and TiO₂:SnO₂ nanocomposite thin films were fabricated by the sol–gel dip coating technique. The mixture was prepared by varying the molar ratio of SnO₂ to TiO₂, i.e. TiO₂:SnO₂ (9:1), TiO₂:SnO₂ (8:2) and TiO₂:SnO₂ (6:4)). The obtained samples were characterized by means of the Raman microscopy, Scanning Electron Microscopy (SEM), UV–Vis spectrophotometry and m-lines spectroscopy (Prism coupler). Raman analysis shows that pure TiO₂ and SnO₂ thin films are characterized by the vibrational modes of anatase and rutile cassiterite, respectively. Furthermore, the Raman spectra of the TiO₂:SnO₂ nanocomposites show the presence of a mixture of anatase and rutile TiO₂ phases. The SEM images reveal that the morphology is clearly modified with SnO₂ content. The ripples in the transmittance spectra decreased with increasing SnO₂ content. Also, the evolution of the optical band gap seems to be consistent with the Raman analysis. A great attention has been paid to the refractive index measurements by the prism coupler technique. In this way, variable–refractive index systems have been successfully obtained using TiO₂:SnO₂ nanocomposite thin films.

In the present review, the effect of porosity on the mechanical properties of the fabricated parts, which are additively manufactured by powder bed fusion and filament extrusion-based technologies, are discussed in detail. Usually, additive manufacturing (AM) processes based on these techniques produce the components with a significant amount of pores. The porosity in these parts typically takes two forms: pores with irregular shapes (called keyholes) and uniform (spherical) pores. These pores are present at different locations, such as surface, sub-surface, interior bulk material, between the deposited layers and at filler/matrix interface, which critically affect the corrosion resistance, fatigue strength, stiffness, mechanical strength, and fracture toughness properties, respectively. Therefore, it is essential to study and understand the influence of pores on the mechanical properties of AM fabricated parts. The technologies of AM can be employed in the manufacturing of components with the desired porous structure through the topology optimization process of scaffolds and lattices to improve their toughness under a specific load. The undesirable effect of pores can be eliminated by using defects-free raw materials, optimizing the processing parameters, and implementing suitable post-processing treatment. The current review grants a more comprehensive understanding of the effect of porous defects on mechanical performance and provides a mechanistic basis for reliable applications of additively manufactured components.

Fragrance is a class of material commonly used in many consumer products such as food and tobacco. Since most of the fragrance is highly volatile, the successful use of fragrance in practical application requires effective preservation of fragrance with appropriate substrate material. As a low cost and versatile material, polymer holds great promise as a fragrance carrier. In this review, we summarize representative polymer carriers developed recently for sustained and controlled release of fragrance, which include natural polymers and novel synthetic polymers. The results summarized in this mini-review would shed light on the future design of advanced fragrance carrier for various applications.

In the research a commercial pure aluminium was cold rolled by 98% accumulative severe plastic deformation and then ultra-fast annealed at 350 °C−520 °C with the 1000 °C/s heating rate and 1.0 s holding time. The microstructure evolution and the mechanisms of the recovery and recrystallization for the above ultra-fast annealed pure aluminium were analyzed by Gleeble 3500 thermal simulation system, electron backscatter diffraction(EBSD),and transmission electron microscopy (TEM). For the ultra-fast annealing pure aluminum, the grain size increases from 2.05 μm to 17.10 μm with the increase of annealing temperature from 410 °C to 520 °C; the tensile strength of the annealed pure aluminium decreases from 116.48 MPa to 53.43 MPa, and the uniform elongation increases from 1.20% to 39.78%. When annealing at 410 °C, the storage energy was transformed into the driving force for grain nucleation, which greatly refined the grains. When annealing at 380 °C ∼ 410 °C, the pure aluminium is in the stage of recrystallization, and the average grain size refined to 2.05 μm. When annealing at 435 °C, the number of small-angle grain boundaries (<15°) was significantly reduced and the number of large-angle grain boundaries increased. When the annealing temperature increased to 470 °C or 520 °C, the crystalline grains had merged each other, leading to the grain size grow to 17.10 μm. The annealing temperature of ultra-fast annealing should be in the range of 410 °C to 435 °C for optimizing the mechanical performances of commercial pure aluminum.

Hydrogel is being broadly studied due to their tremendous properties, such as swelling behavior and biocompatibility. Numerous review articles have discussed hydrogel polymer types, hydrogel synthesis methods, hydrogel properties, and hydrogel applications. Hydrogel can be synthesized by physical and chemical cross-linking methods. One type of the physical cross-linking method is freeze-thaw (F–T), which works based on the crystallization process of the precursor solution to form a physical cross-link. To date, there has been no review paper which discusses the F–T technique specifically and comprehensively. Most of the previous review articles that exposed the hydrogel synthesis method usually mentioned the F–T process as a small part of the physical cross-linking method. This review attempts to discuss the F–T hydrogel specifically and comprehensively. In more detail, this review covers the basic principles of hydrogel formation in an F–T way, the parameters that influence hydrogel formation, the properties of the hydrogel, and its application in the biomedical field.

Green synthesis has emerged as a reliable, sustainable and ecofriendly protocol for synthesizing a wide range of nanomaterials and hybrid materials. In this paper, we report the synthesis of Copper oxide nanoparticles by a simple biological route using the extract of Brassica oleracea var. italic and copper (II) acetate as the metal precursor. The synthesized copper oxide nanoparticles were characterized using UV–visible spectroscopy, FTIR spectroscopy, FESEM, EDAX, and XRD techniques. UV –Visible analysis shows a characteristic peak around 220 nm for copper oxide nanoparticles. FTIR spectroscopy was used to characterize various capping and reducing agents present in the plant extract responsible for nanoparticle formation. The surface morphology was characterized using FESEM. The EDAX and XRD pattern suggested that prepared copper oxide nanoparticles were highly pure. The average particle size was calculated as 26 nm using the XRD technique. Further, the nanoparticles were found to exhibit the highest antifungal activity against Aspergillus niger and Candida Albicans.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted extensive attraction due to their unique properties in novel physical phenomena, such as superconductors, Moiré superlattices, ferromagnetics, Weyl semimetals, which all require the high quality of 2D TMDs. Mechanical exfoliation (ME) as a top-down strategy shows great potential to obtain 2D TMDs with high quality and large scale. This paper reviews the theoretical and experimental details of this method. Subsequently, diverse modified ME methods are introduced. Significantly, the recent progress of the Au-assisted ME method is the highlight. Finally, this review will have an insight into their advantages and limitations, and point out a rational direction for the exfoliation of TMDs with high quality and large size.

Double perovskites, which can host two different transition metal cations at the B-sites of its perovskite derived structure, provide the possibility to explore the interplay of localized 3d transition metals and the relatively delocalized 4d or 5d transition metals within the same structure. This interplay gives rise to extraordinary magnetic properties. In this overview article, we summarize our recent computational efforts in understanding the curious properties of magnetic double perovskites with 3d and 4d/5d transition metal ions, make predictions on new functionalities in known compounds of this family, engineering functionalities via chemical modifications/doping and prediction on a new set of magnetic 3d-4d/5d double perovkite compounds, which may be synthesized to explore and expand further this interesting family.

Cobalt oxide nanoparticles (Co₃O₄-Nps) have many applications and now a days the green methods of synthesis of these NPs are preferred over other methods because of associated benefits. In this study, Co₃O₄-Nps were synthesized by using leaves extract of Populus ciliata (safaida) and cobalt nitrate hexa hydrate as a source of cobalt. The synthesized NPs were analyzed by different techniques such as fourier transform spectroscopy (FTIR), x-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Antibacterial activities of the synthesized Co₃O₄-Nps were evaluated against gram negative and gram positive bacteria and found active against Escherichia coli (E. coli), Klebseilla pneumonia (K. pneumonia), Bacillus subtillus (B.subtillus) and Bacillus lichenifermia (B. lichenifermia). The activity results were analyzed statistically by one-way ANOVA, with 'Dunnett's Multiple Comparison Test'. The maximum mean activity (21.8 ± 0.7) was found for B. subtilis and minimum mean activity (14.0 ± 0.6) was observed for E. coli.

The oxidation behavior of 316L stainless steel exposed at 400, 600 and 800 °C air for 100, 500 and 1000 h was investigated using different characterization techniques. Weight gain obeys a parabolic law, but the degree of deviation of n index is increasingly larger with the increase of temperature. A double oxide film, including Cr₂O₃ and Fe₂O₃ oxide particles in outer and FeCr₂O₄ oxides in inner, is observed at 400 °C. As regards to samples at 600 °C, a critical exposure period around 100 h exists in the oxidation process, at which a compact oxide film decorated with oxide particles transforms to a loose oxide layer with a pore-structure. In addition, an oxide film containing Fe-rich outer oxide layer and Cr-rich inner oxide layer is observed at 600 °C for 500 and 1000 h. Spallation of oxide scale is observed for all samples at 800 °C regardless of exposure periods, resulting in different oxidation morphologies, and the degree of spallation behavior is getting worse. A double oxide film with the same chemical composition as 600 °C is observed, and the thickness increases over exposure periods.

Collagen is a type of natural biopolymer material, which is widely used in tissue engineering and medicine owing to its exceptional properties such as biodegradability, biocompatibility, hemostatic properties, and low immunogenicity. Collagens from different sources can differ in type, structure, and function. In this study, collagen was extracted from swim bladder and bovine Achilles tendon by acid-enzyme binding method at low temperature. UV spectrum, Fourier transform infrared spectrum, sodium dodecyl sulfate–polyacrylamide gel electrophoresis, scanning electron microscope, and differential scanning calorimetry were used to characterize these two collagens. The blood compatibility and cytotoxicity of the two kinds of collagen were studied.The results showed that the collagens from the two sources belong to the characteristics of type I collagen and had biological safety. Their differences in structure and thermal stability can provide a theoretical basis for the selection of collagen in practical application.

This study examines the potential use of Electrolytic Manganese Dioxide (EMD) residue as a replacement of cement (20%wt by cement weight) in construction materials to provide anticorrosion protection on reinforcing steel and improve the strength of cementitious materials under sulfate attack. To assess the corrosion parameters, the constructed building materials were immersed in a 5%wt sulfate salt (Na₂SO₄), while concrete samples incorporating 20%wt EMD were prepared and subjected to mechanical, porosity and thermal tests. Moreover, SEM images were obtained in order to examine the microstructure of concrete and the extent of damage caused by sulfate ions. The results demonstrate that the inclusion of EMD caused a notable rise in the corrosion of steel bars within cement mortars, as well as a decrease in the mechanical strength of the building materials. Overall, the experimental outcomes of the study suggest that the incorporation of high volume (20%wt) EMD residue leads to the degradation of all measured properties.

Electrokinetics effectively removes contaminants, but its field-scale applications are limited mainly due to its high energy cost. In previous studies, the energy consumption was determined either by changing the soil's specimens initial salt concentration while keeping the treatment time fixed or by changing the treatment time and keeping the same initial salt concentrations for all the specimens. Since both the initial salt concentration and treatment time are important parameters in determining reclamation cost, therefore, in this study, the soil specimens intentionally contaminated with different concentrations of sodium chloride (NaCl), i.e., varying from 3.7 to 15.5 g kg⁻¹, were exposed to a constant DC electric field of 1 V cm⁻¹ for different time durations, i.e., varying from 6 to 72 h. The results show that electroosmotic flow (EOF) was directed from the anode to the cathode and higher for specimens contaminated with relatively low salt concentration, i.e., up to 7.6 g kg⁻¹. Therefore, for these specimens, due to the combined effect of electroosmosis and electromigration, the removal of Na⁺ was higher than the Cl⁻. However, for the specimen contaminated with a higher salt concentration, i.e., 15.5 g kg⁻¹, the Cl⁻ removal exceeded Na⁺ due to the marginalization of EOF. Regardless of initial salt concentration, the electroosmotic flow and salt ions removal rates decreased with increasing treatment time, which might be attributed to the development of acidic and alkaline environments in soil. The collision of acidic and alkaline fronts resulted in a large potential gradient in a narrow soil region of pH jump, diminishing it everywhere else. This nonlinearity in the electric potential distribution in soil reduced the EOF and electromigration of salt ions.

Natural dyes are gaining a great deal of attention due to their eco-friendly and sustainable properties for advanced apparel applications. However, the reproducibility and accessibility of various colors using natural dyes remain challenging. In this study, plant-extracted fluorescent protein C-phycocyanin (CP) is used as a natural dye source and doped in polyvinyl alcohol (PVA) nanofibers via electrospinning for advanced apparel applications. The prepared nanofibers show a smooth and bead-free surface morphology. The FTIR results confirmed the formation of PVA nanofibers followed by a major peak at 3304 cm⁻¹ due to the stretching of hydroxyl groups. Subsequently, CP-doping in PVA nanofibers is observed by the N–H deformation peaks at 1541 cm⁻¹; C–N stretching vibrations at 1250 cm⁻¹ and 1092 cm⁻¹; and the C=O stretching vibrations of the carboxyl group at 1722 cm⁻¹, respectively. Thus, CP-doped PVA nanofibers exhibit a good color strength (K/S) of 0.2 having a blue color tune and good color fastness properties. The mechanical strength of PVA nanofibers increased from 6 MPa to 18 MPa, due to crystalline characteristics endowed by the dope dyeing technique. Further, CP-doped PVA nanofibers exhibit homogeneous bright red fluorescence in individual nanofibers. Therefore, the proposed CP-doped PVA nanofibers can be used for flexible advanced apparel and biosensor applications.

Ultra-high-density zircon (ZrSiO₄) ceramics were prepared using the spark plasma sintering (SPS) technique of zircon nanopowder with the addition of three different sintering agents, i.e., Bi₂O₃, V₂O₅ and B₂O₃. The effect of each agent and the SPS parameters (temperature and pressure) on phase composition, microstructure, thermal and mechanical properties of the ceramics were evaluated. The identified crystalline phases of the sintered ceramics were zircon and monoclinic zirconia. The addition of a sintering agent affects the structure of zircon ceramics, i.e. the lattice parameter and the crystallite size. The sintered ceramics reached relative densities up to 99.9% of the theoretical one when V₂O₅ or B₂O₃ was added. SEM observations confirmed the densification of the zircon ceramics. We found the ceramics exhibited thermal conductivity ranging from 0.39 to 0.61 Wm⁻¹K⁻¹ at 373 K while the coefficient of thermal expansion was 2.3–4.0 × 10⁻⁶/°C and the Vickers hardness was obtained to be 9.52–12.66 GPa. The Young's (E), bulk (B), and shear (G) moduli, Poisson's ratio ν, Pugh's ratio B/G, and the ratio of of the ceramics are in a range of 240 − 288 GPa, 207 − 267 GPa, 91 − 109 Pa, 1.95 − 2.45, and 0.011 − 0.019 respectively. We found that high-density, quasi-ductile zircon ceramics can be synthesized at a low sintering temperature and short holding time.

Sportswear is an essential auxiliary wear for physical education activities in colleges and universities. Unfortunately, most sports equipment is made of heavyweight, expensive, and easily rusted metals. Herein, we report the recent progress in carbon-based nanocomposites for sportswear and sensors. To extend the service life of sportswear, advanced lightweight materials for sports goods are briefly discussed. Carbon materials such as 0D fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite and their nanocomposites are more and more widely used in various industries in the world, and sportswear has no exceptions. Their superior performance and huge potential have a certain impact on improving sports performance. Firstly, we overviewed the advantages and multifunctional carbon nanocomposites in sportswear, and wearable sports applications at the present stage are explored. While simultaneously monitoring health or energy storage applications also explored, indeed the integration of all desirable functions into lightweight wearable sports goods emerged as a significant breakthrough for effective sports activities. More importantly, some sportswear prototypes equipped with unprecedented characteristics have also been overviewed in this review. Despite the recent developments, many barriers and difficulties still remain. New prospects are also suggested. This article seeks to inspire sports research communities to drive onward real-time advancement in the sports industry.

GaAs is well known for its extremely high electron mobility and direct band gap. Owing to the technological advances in silicon-based technology, GaAs has been limited to niche areas. This paper discusses the application of GaAs in molecular electronics and spintronics as a potential field for considering this amazing but challenging material. GaAs is challenging because its surface is characterized by a high density of surface states, which precludes the utilization of this semiconducting material in mainstream devices. Sulfur(S)-based passivation has been found to be significantly useful for reducing the effect of dangling bonds and was researched thoroughly. GaAs applications in molecular spintronics and electronics can benefit significantly from prior knowledge of GaAs and S interactions because S is a popular functional group for bonding molecular device elements with different semiconductors and metals. In this article, the problem associated with the GaAs surface is discussed in a tutorial form. A wide variety of surface passivation methods has been briefly introduced. We attempted to highlight the significant differences in the S-GaAs interactions for different S passivation methods. We also elaborate on the mechanisms and atomic-scale understanding of the variation in surface chemistry and reconstruction due to various S passivation methods. It is envisioned that GaAs and thiol-terminated molecule-based novel devices can exhibit innovative device characteristics and bring the added advantage of S-based passivation.

Chloride ion corrosion of steel bars is one of the important reasons for the decline of durability and service life of concrete structures. Due to the complexity of concrete structure, the migration process of chloride ions in concrete is diversified. Therefore, it is difficult to show the transport mechanism of chloride ions in concrete by a single experimental study. It is necessary to explore the transmission process and mechanism of chloride ions in concrete through theoretical simulation on the basis of experimental research. This paper summarizes the relevant models and methods of chloride transport, points out the advantages and disadvantages of existing models, and prospects the research direction of chloride transport models.

For the excellent drug delivery systems, advanced functional materials are indispensable. In recent years, mesoporous materials have shown a promising prospect and attracted much attention in the field of drug delivery. The research of mesoporous materials as drug carriers becomes to be a hot-spots. As a drug vehicle, it is favored by scientists due to the advantages in increasing drug dissolution and bioavailability, improving drug stability, sustained and controlled drug release, reducing drug side effects, good biocompatibility, targeting and so on. The anticipated in vivo performance for the mesoporous materials based drug delivery systems can be improved through optimizing the synthesis conditions or modifying the materials. In the paper, mesoporous silica nanoparticles (MSNs), mesoporous carbon nanoparticles (MCNs), organic frameworks (OFs), mesoporous hydroxyapatite (mHAp) are selected as the representative mesoporous materials. The structural characteristics, preparation methods, application in the field of drug delivery of above materials are reviewed, and the future research is prospected.

Nanotechnology has facilitated unique ways of developing novel nano-composites. In that sense, polymer-based nano-composites are being extensively researched for their outstanding properties as a result of incorporating nano-fillers in the polymer matrix. They have activated enormous research interests owing to their potential in addressing environmental issues, packaging, optics, electronics, battery electrolytes, pneumatic actuation, molecular separations, sensors, biomedical applications, etc Hence, the authors intend to consolidate reported information about these polymer matrices, diverse inorganic nanofillers, and nano-filled polymer composites for improvement in properties and future advanced applications. The review exhaustively covers 15 years of literature on theoretical, experimental, and application aspects of PVA & PMMA-based nano-composites, mainly focusing on inorganic oxide-based fillers. It also summarizes the structure-property correlations that govern their performance. Hence this review is hoped to provide the readers with stimulating insights on strategies, noteworthy challenges, and future opportunities/prospects in developing polymer nano-composites that may cater to the need of our society and scientific industries as well.