Table of contents

This volume contains selected and peer-reviewed papers presented at the 5th Padjadjaran International Physics Symposium (PIPS 2022), which was held on February 10, 2022 Virtually using ZOOM due to COVID-19 pandemic. The conference was held every two years and organized by Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Indonesia. The main theme of PIPS 2022 was "Reposition the Role of Physics in Sustainable Development". PIPS 2022 aims and dedicates itself to providing networking possibilities for researchers, scientists, engineers and scholars to share their experience, amazing ideas and innovative research in the field of Materials Science and Engineering.

The virtual conference contained one full-day technical sessions consisting of keynote lectures and oral presentations. The technical program consists of 3 keynote speech, 4 invited speech and 42 oral presentations using 5 virtual rooms. Every presenter was given 10-15 minutes for presentation, and each keynote was given 45 minutes.

These selected papers are focused on recent research results in materials for application in for environment and energy, instrumentation, sensor and software development, computational modelling, synthesis, and characterization of new emerging advanced in magnetics materials and superconductors, photocatalyst, materials for biomedical practice, and other functional materials. We hope this volume can bring close collaboration among researchers from multidiscipline areas for better future development of energy and advanced materials.

Finally, we are very grateful to all organizing committee members and reviewers for invaluable supports, comments and suggestions. On behalf of the conference organizing committee, we would like to show our congratulation and sincere gratitude to all authors, peer reviewers, speakers and oral presenters and listeners. We deeply appreciate their efforts in making the conference successful.

List of Committee Member are available in this pdf.

All papers published in this volume have been reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing Publishing.

• Type of peer review: Single Anonymous

• Conference submission management system: Morressier

• Number of submissions received: 22

• Number of submissions sent for review: 20

• Number of submissions accepted: 18

• Acceptance Rate (Submissions Accepted / Submissions Received × 100): 81.8

• Average number of reviews per paper: 2.0555555555555554

• Total number of reviewers involved: 12

• Contact person for queries:

Name: Budi Adiperdana

Email: budi.adiperdana@phys.unpad.ac.id

Affiliation: Padjadjaran University - Physics

The performance of tuna fishbone waste as carbon to remove iron (Fe) metal from well water was studied. The parameters of carbon synthesis were set by varying the carbonization temperature of 300, 400, and 500°C. Fishbone carbon was characterized using Scanning Electron Microscopy (SEM-EDX), X-ray Diffraction (XRD), and SSA (nitrogen adsorption). The BET and (BJH) analysis showed that the increase in carbon surface area and pore size was proportional to the increase in carbonization temperature. Fishbone carbon was used as a filtration medium to reduce high levels of iron metal in well water. Samples were taken from wells belonging to residents in Bandar Setia, Medan Tembung. Fishbone carbon was effective as an adsorbent for removing iron metal from well water by the filtration method. The rate of iron removal was 99% for fishbone carbon, carbonized at 400°C.

Eggshell (ES) membrane is a semipermeable membrane that is insoluble in water and has a high surface area. We modified ES membranes with graphene oxide (GO) using self-assembled technique and used it to remove dye pollutants such as methylene blue (MB) in water. The ES membranes were obtained from fresh eggs that have been removed from albumen and yolk, then immersed in 15% acetic acid for 30 minutes. The ES membranes were immersed in 0.5 mg/mL dispersed GO and ultrasonicated for 3 hours. The modified ES-GO membrane was then used to filter 5 mg/L MB solutions. Filtration of MB solution was performed by pouring the solution over the ES-GO membrane with a help of constant pressure of 45 psi. We found that the modified ES-GO membrane could filter MB up to 33.53% and reduce MB concentration from 4.91 mg/L to 3.53 mg/L. The result of membrane permeability is 2.488 x10⁻³ darcy and the flow rate of the filtration is relatively constant about 4 mL/s.

Zinc Oxide (ZnO) and Titanium Dioxide (TiO₂) are metal oxides that are commonly used as photocatalysts material due to photoactivity characteristics. ZnO has a better reduction potential, and high electron mobility, but has a lower contact surface area than TiO₂. On the other side, TiO₂ has a better photoactivity to degrade pollutants referring to high surface area but has lower electron mobility compared to that ZnO. The combination of these two metal oxides is estimated can produce a better photocatalytic activity due to the advantages of each characteristic. Therefore, in this research, the ZnO-TiO₂ (1:1) was prepared and investigated. ZnO nanoparticle was synthesized by the sol-gel method using zinc acetate dihydrate as a precursor, before calcining process, anatase TiO₂ powder was added to form the composite. Structural, morphological, and optical characteristics of composite powders were analyzed by using XRD, TEM, UV-Vis Spectroscopy, and PL Spectroscopy. The concentration degradation of methylene blue in a solution containing composite material was observed to determine the photocatalytic activity under UV light irradiation for 30 minutes. The XRD spectrum shows the anatase phase of TiO₂ and hexagonal wurtzite of ZnO crystal structure. Based on TEM imaging ZnO nanoparticles were attaching to TiO₂ surfaces estimated due to van der walls bond. The ZnO/TiO₂ shows a better photoactivity up to 20 minutes reaction with a higher degradation constant rate that indicates faster methylene blue degradation.

Fine bubbles (micro to nanometer-sized) have rapidly gained popularity in academia and industry due to their unique properties, such as their high surface area, stability, and longevity. In this study, the performance of oxygen transfer rate efficiency in fine bubbles with high purity oxygen and atmospheric air was analyzed. In this study, the developed fine bubbles generator with power requirement 300 watt was used to evaluate the production of fine bubbles and oxygen transfer efficiency at two type gas sources i.e., ambient air and high-purity oxygen in the small bench aqueous media (5 L water tank). The fine bubbles generator was set up at the pressure in 50 psi and gas flow rate at 0.3 L/min to produce fine bubbles in water medium. The effect of water recirculation process in the bubbles production was measured using particles size analyzer (PSA), zeta potential and dissolved oxygen (DO) meter to measure temperature and dissolved oxygen on the water. Dissolved Oxygen (DO) measurement shows the saturation value of oxygen concentration in water, for high purity oxygen is 30 mg/L higher than air which has a value of 8.64 mg/L. This causes the efficiency of gas transfer in high-purity oxygen to reach 72.09% higher than ambient air at 35.39%. The particle size distribution shows that the mean size of bubbles after 10 minutes recirculation was 465.5 nm and 599.9 nm correspondingly for ambient air and oxygen gas source. High purity oxygen also affect to the zeta potential value tends to be more negative than in ambient air. The type of high-purity oxygen gas can increase the efficiency of the oxygen transfer rate so that the gas containing high-purity oxygen increases the volumetric oxygen transfer rate coefficient which is 2 times higher than using ambient air.

Perovskite methylammonium lead tri-bromide (MAPbBr₃) material has gained a lot of attention in the past few years due to its impressive optoelectronic properties, which is suitable for high efficiency and sensitivity X-ray photodetector. Compared to polycrystalline crystal structure, MAPbBr₃ single crystal is more ideal for X-ray photodetector because lack of grain boundary therefore produce more sensitive photodetector. However, a cubic structure and large crystal dimension is highly required to adjust into the flat-panel detector configuration. In this research, MAPbBr₃ perovskite crystals were synthesized by using Anti-solvent Vapor-assisted Crystallization (AVC) at room temperature using dimethylformamide (DMF) as solvent and Dichloromethane (DCM) as antisolvent. The precursors for the MAPbBr₃ solution were prepared by varying the molar ratio of MABr:PbBr₂ as precursor solution. The crystal growth rate was controlled by varying the volume ratio of DCM and MAPbBr₃ precursor solution. The obtained largest crystal size of 10 mm × 10 mm was prepared with a volume ratio of DCM and precursor is 3 and a volume of precursor solution is 6 ml. The XRD of large cubic MAPbBr₃ crystal showed a peak of (100) plane, which indicates a single crystal oriented in a-axis direction. The Raman spectra peaks of perovskite MAPbBr₃ crystals showed organic (MA⁺) and inorganic (PbBr₂⁻) bonds in a cubic phase of single crystal MAPbBr₃. All samples that were prepared with different ratios of DCM and precursor solution have the same Raman spectra, which confirm that all MAPbBr₃ crystals have cubic crystal structure.

Pseudocapacitor is a supercapacitor that can store charge faradically through a reversible redox reaction. Polyaniline (PANi) is one of the promising active materials for pseudocapacitor electrodes since it can produce theoretical specific capacitance up to 750 F/g. We prepared leucomeraldine base polyaniline (LB-PANi) electrodes by deposition of dissolved LB-PANi powder in N,N-Dimethylformamide (DMF) using spraycoating technique. The LB-PANi electrodes was then doped with 1 M HCl through protonation process to obtain emeraldine salt polyaniline (ES-PANi) electrodes. We used both electrode materials and 1 M KCl to prepare a symmetrical sandwich supercapacitor model of <LB-PANi|KCl|LB-PANi> and <ES-PANi|KCl|ES-PANi>, as well as measured their performance. The results show a significant increase of the specific capacitance of PANi supercapacitor from 15.02 F/kg to 1876.87 F/kg when the electrodes of the LB-PANi were changed with the ES-PANi electrodes.

Photoanode of dye-sensitized solar cell (DSSC) is an inorganic semiconductor layer with a nanoporous structure that has a function as a charge carrier transport layer and dye storage. Oxide semiconductor material such as titanium dioxide (TiO₂) is widely used as a photoanode because of its wide band gap (3.2 eV) and high active surface area (80 m²/g), but TiO₂ has low electron diffusion with high recombination (electron-hole pair pairing). To improve the electron diffusion and reduce recombination, TiO₂ was modified with zirconia (ZrO₂). The synthesis process was carried out using sol-gel method with variations of ZrO₂ concentrations at 5 mol%, 10 mol%, and 15 mol%. Composite of TiO₂/ZrO₂ was then applied as a photoanode of DSSC. XRF results show that in all variations of ZrO₂, the composites of TiO₂/ZrO₂ has been formed. Based on the results of UV-Vis spectroscopy, it was shown that the energy gap of TiO₂/ZrO₂ decreased as the increasing of ZrO₂ concentration. The current density-voltage measurement was done to investigate the effect of ZrO₂ addition to the TiO₂ photoanode using light irradiation with power intensity of 100 mW/cm². There is an increasing of photocurrent from 1.63 mA/cm² of DSSC with TiO₂ photoanode to 2.79 mA/cm² of DSSC with TiO₂/ZrO₂ 10 mol% photoanode. The highest efficiency obtained from DSSC with TiO₂/ZrO₂ photoanode is 1.15%. It was found that the presence of ZrO₂ in the composite of TiO₂/ZrO₂ increased electron transport and reduced charge recombination to improve the photocurrent of DSSC.

In the overdoped regime of superconductors, both electron- and hole-doped superconductors exhibit intriguing phenomena like the Quantum Critical Point. Other phenomena, such as cooper-pair breaking and stripe pinning, can be observed by eliminating superconductivity by the addition of impurities. In this study, we investigate the crystal structure and magnetic properties of electron-doped superconducting cuprates of Eu_2-x+yCe_x-yCui_1-y Fe_y O_4+α-δ in the overdoped regime of x = 0.17 for Ce doping with y = 0.005, 0.01 and 0.03 for Fe impurity. The material has a tetragonal T' structure that matches the ECCO crystal structure, according to the XRD analysis of the crystal structure. The addition of magnetic impurity has no effect on the structure but does decrease the lattice parameter. SQUID was used to measure the magnetic susceptibility at low temperatures between 2 K and 30 K. The spin-glass was observed at y = 0.03, due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction as shown in a hole-doped system. Due to the significant contribution from the magnetic moment of the Fe ion, the addition of Fe concentrations increases the effective magnetic moment. The conduction layer's spin correlation of Cu is dramatically disrupted by the addition of Fe, resulting in the breakage of the copper-pair and the elimination of superconductivity.

Known as the next wonder material after graphene, hexagonal form of Boron-Nitride (hBN) attracts a lot of interest due to its capabilities to be utilized in wide range of applications. Here we investigate bilayer structure of hBN using density functional theory (DFT) techniques. In pristine case, we observed that the SCAN functional gives a significantly better estimation of inter-layer distance compared to the PBE functional. Furthermore, we also modelled the hBN structure with a single oxygen molecule sandwiched in between of B-N layer, and conclude that the most probable sites for oxygen molecule to be trapped is at the exact center of the bilayer hBN structure.

Density functional theory (DFT) calculation are carried out for the cubic structure of lithium fluoride (LiF). Variation of applied pressure is considered, ranging from 0 to 120 GPa with an increment of 30 GPa based on PBE and SCAN functional scheme. In zero pressure and energy-cut off 100 Ry, best result on lattice parameter is obtained by using PBE functional with the value of 4.06 Å, while SCAN functional overestimates the lattice parameter at 4.15 Å. The insulating gap of both results is significantly underestimated with 8.82 eV and 9.26 eV for PBE and SCAN functionals respectively. With the applied hydrostatic pressure, the lattice parameter are reduced exponentially, while still retaining the insulating behaviour with an increased value of gap energy.

Silicon carbide is considered to be one of the superhard material with the microhardness value more than 20 GPa. Here we report the theoretical study based on density functional theory methods on the SiC system. Three different semilocal functionals of LDA-PZ, GGA-PBE, and SCAN are utilized. The cubic crystal structure of SiC are used in all of our calculations that is fully-relaxed to obtain realistic description of both structural and electronical parameters. For the lattice parameter and insulating gap estimation, SCAN functional gives the best comparison with the experimental value with 4.34 Å and 1.67 eV respectively. The calculated Vickers hardness formula based on the SCAN functional gives the value of 36 GPa

Benzoyl peroxide (BPO) is one of the bleaching agents for flour that is widely used in food products, such as bread and noodles, which if consumed continuously can cause health problems. An excess of BPO in the body will cause vertigo, vomiting, neurasthenia, and a variety of diseases, resulting in serious damage to the liver and other organs. In this work, a colorimetric sensor using CsPbBr₃ nanocrystal (NC) was studied to measure the BPO concentration in the solution. The halogen ion exchange reaction between CsPbBr₃ NCs and iodine (I⁻) was carried out by adding oleylammonium iodide (OLAM-I) to the CsPbBr₃ NC solution. The results show that the originally green emission of CsPbBr₃ NC (515 nm) is turned into red-pink (660 nm) after addition with OLAM-I due to iodide ions exchange with bromide ions in CsPbBr₃ NCs. The wavelength shift was occurred rapidly, only in 1 minute. The emission of CsPbBr₃+OLAM-I (660 nm) solution was blue-shifted rapidly within 1-2 minutes after BPO addition. The magnitude of the emission wavelength shift proportional to the concentration of BPO concentration, with a higher concentration leads a higher wavelength shift (Δλ). Therefore, this wavelength shift can be used as rapid and real-time sensor for detecting BPO content in the real samples of white flour and noodles.

The low-cost quartz crystal microbalance (QCM) instrument with the microcontroller as the basis of the embedded system of the frequency counter was implemented. The system uses a quartz crystal transducer from the crystal oscillator component. The frequency shifting was observed and analysed in association with some experimental tests. The experiments such as ethanol evaporation, water vapor in the humidity chamber, and coating the surface with TiO₂ particles had been conducted. The developed QCM instrument has shown the ability to measure the frequencies in response to the addition or reduction of mass on the surface of the crystal oscillator. These responses are caused by evaporation, humid condition, and deposited particle on the quartz crystal surface. The QCM was varied into two initial frequencies, 5 and 10 MHz. The 5 MHz system represents the proper "in range" frequency counters, inside a counting limit of the microcontroller up to 5.6 MHz. On the other side, the 10 MHz is an experimental development system. Both types utilise a D flip-flop frequency divider that made a microcontroller-based frequency counter and can count the frequency twice the limit. The more stable 10 MHz have shown promising potential application related to the surface interaction with other material and can hold thicker deposition on its surface with a better stability response than the lower frequency counterpart.

Titanium dioxide (TiO₂) is an attractive semiconductor oxide compound due to its good stability properties both in chemical and photochemical. TiO₂ in the form of nanofibers offers many advantages such as high surface area, flexibility of structures and mechanical properties such as stiffness and tensile strength. In this study, we reported the synthesis of TiO₂ nanofibers using electrospinning technique. TiO₂ nanofibers were produced from titanium (IV) iso-propoxide precursor solution at different applied voltages of 10 kV and 12 kV, while the flowrate was kept constant at 0.7 ml/hours during the process. The electrospinning process produced a thin layer of nanofibers which was then calcined for 1 hour at different calcination temperature. Based on the SEM images, we found that at applied voltage of 12 kV uniform and continuous nanofibers had already formed with the average diameter of nanofibers was in the order of sub microns. The diffraction pattern of TiO₂ nanofibers shows that at a calcination temperature of 450°C, the phase was dominated by the anatase phase, while at 500°C it has a combination of anatase and rutile phases. Based on UV-Vis spectroscopy, it was found that the energy gap of TiO₂ nanofibers calcined at temperature of 450°C and 500°C were 3.32 eV and 3.22 eV, respectively.

The local geological and the physical conditions of earth's ground defines its vibration characteristics. Such vibrations can be detected using conventional passive seismic methods, i.e., a microtremor recording method, which acquires ground vibration data in a suitable sampling time. The method utilizes natural seismic sources, originating from both natural and artificial sources. In this work we present the algorithm to process passive seismic signals, recorded from a laboratory developed triaxial seismic logging device. We use python scripting language to perform the signal processing work. We analyzed the Horizontal to Vertical Spectral Ratio (HVSR) of the signal to determine the on-site natural frequency. The results were compared to the reference data from a high sensitivity microtremor apparatus, at the exact same location. The results show a fair agreement between the low sensitivity and the high sensitivity seismometer, on the sites with low environmental disturbance. However, the values fluctuate significantly at noisy sites. Either way, our results measure the correct dominant frequencies as expected from the geological condition.

The vertical cylinder tank can serve as a measuring tool and as a storage device. When the vertical cylinder tank is used as a measuring instrument, it needs to be calibrated. In this process, measuring the diameter of the vertical cylinder tank is the most important step. The diameter of the tank is divided into several parts, the first part is referred to as a reference, where the results of the reference measurement will be used in the measurement of other parts. To conduct this measurement, a prototype consisting of two sensors, namely, laser distance and rotary encoder, is build. The prototype was tested using five variations in standard tube diameters measured using a steel ruler. The results of this test produce an average correction of +0.17 mm with an error of 0.59%. Furthermore, the prototype is used to measure the diameter of the vertical cylinder tank, which is compared with the certificate of the results of tank measurements using a theodolite. Testing the prototype with a vertical cylindrical tank produces a correction of +8.73 mm with an error of 0.03%. This error value is within the error limit according to the OIML International Recommendation of R-071 for vertical tanks.