Effect of Graphene Nanoparticles Addition on Superconductivity of YBa2Cu3O7~δ Synthesized via the Thermal Treatment Method

The development of high-temperature superconductor (HTS) YBa2Cu3O7~δ (Y123) bulks in industrial applications were established years ago. It is one of the developments that currently attracts great attention especially in transportation, superconductor cables and wires. This study is focused on the preparation of the Y123 bulk superconductors by the thermal treatment method due to the promising ways to develop high-quality Y123 superconductors with its simplicity, low cost, and relatively low reaction temperature used during the process. Y123 were added with graphene nanoparticles (x = (0.0–1.0) wt.%). Samples were then characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and alternating current susceptibility (ACS). It was found that Y123 confirmed that the majority of phases in all the XRD patterns was the orthorhombic crystal structure and the Pmmm space group with secondary phases belonged to Y2Ba1Cu1O5 (Y211). The highest Tc obtained when graphene nanoparticles were added in the Y123 sample was x = 1.0 wt.%, followed by x = 0.5 wt.% with 92.64 and 92.59 K, respectively. From the microstructure analysis, the average grain size significantly decreased to 4.754 µm at x = 0.5 wt.%. The addition of graphene nanoparticles had disturbed the grain growth of Y123, affecting the superconducting properties of the samples. On the other hand, the intergranular critical current density, Jcm, was found to increase with graphene nanoparticle addition and had the highest value at x = 1.0 wt.%, indicating that graphene nanoparticles acted as pinning centers in the Y123 matrix.

(R)-Baclofen [(R)-4-amino-3-(4-chlorophenyl)butanoic acid]

This article provides the first single-crystal XRD-based structure of enantiopure (R)-baclofen (form C), C10H12ClNO2, without any co-crystallized substances. In the enantiopure title compound, the molecules arrange themselves in an orthorhombic crystal structure (space group P212121). In the crystal, strong hydrogen bonds and C—H ... Cl bonds interconnect the zwitterionic molecules.

Hydrothermal synthesis of ABi2Ta2O9Aurivillius phase: A comparative study of A-site cation size on structure, dielectric, optical properties

In this study, the double-layered Aurivillius phases CaBi2Ta2O9 (CBT) and PbBi2Ta2O9 (PBT) were prepared through a hydrothermal route with NaOH as a mineralizer. XRD analysis confirmed that the CBT and PBT compounds were successfully formed and adopted an orthorhombic crystal structure with an [Formula: see text]21am symmetry. Le Bail refinements of XRD data indicated that the unit cell volume of CBT was smaller than PBT and is associated with the smaller ionic radius of Ca[Formula: see text] compared to Pb[Formula: see text]. The surface morphology of both samples, as determined using SEM, demonstrated plate-like grains with anisotropic grain growth. It was found that the different ionic radii of [Formula: see text]-site cations (Ca[Formula: see text] and Pb[Formula: see text] strongly affected the structural, optical and electrical properties of the Aurivillius phase. The occupation of smaller Ca[Formula: see text] cations induced a higher structural distortion, which resulted in higher bandgap ([Formula: see text] energy and ferroelectric transition temperature ([Formula: see text] of CBT, compared to those of PBT.

The facile one-step hydrothermal method to prepare MnO2 nanoparticles: Structural and electrochemical properties

MnO2 nanoparticles were successfully prepared via one-step hydrothermal method. The surface are properties of the MnO2 nanoparticles were determined by BET nitrogen adsorption-desorption measurement. The XRD analyses confirm the pure phase of γ-MnO2 and α-MnO2, having orthorhombic crystal structure (JCPDS file no.14-0644 and 44-0141). FE-SEM analysis reveals the combination of massively small spherical particles with average particle size 54.8 nm. The electrochemical results revealed that the MnO2 nanoparticles delivered the specific capacitance of 200.83 F/g at a current density of 1A/g. The cycle stability was usability 30% after 500 cycles at a current density of 5 A/g. The MnO2 nanoparticles reveal a energy density of 3.62 Wh/kg under a power density of 43.11 W/kg.

Barium titanate piezoelectric-film-based beam-array airflow sensor for wearable breath-monitoring application

This study presents a barium titanate (BaTiO3) film-based piezoelectric airflow sensor. This sensor integrated a piezoelectric beam array with a poly(dimethylsiloxane) orifice membrane as the core sensing component. The compact size of the micromachined device fit the requirements for a wearable device. The hydrothermally grown barium titanate film exhibited an orthorhombic crystal structure with good piezoelectric properties. We propose an algorithm to determine the airflow sensor performance using data from the measured piezoelectric signal and the displacement of the piezoelectric beam. This algorithm correlates the discharge coefficient of the core sensing component, Reynold’s number, airflow velocity, pressure difference across the component, displacement of the piezoelectric beam, strain of the barium titanate film, and generated charge from the sensor, which is rarely reported in the literature. The Young’s modulus and piezoelectric constant of the barium titanate film could also be derived as 100 GPa and 8 pC/N, respectively. Utilizing this algorithm and the generated piezoelectric signal of the sensor, important breath parameters of a young male subject at rest were monitored.

Growth and some surface characterization of tin Sulphide (SnS) thin film by two-electrode cell arrangement for photo absorption

This study presented deposition of tin sulphide (SnS) thin film using a two-electrode electrochemical cell arrangement. The bath electrolyte comprised tin sulphate (SnSO4 ), hydrated sodium thiosulphate (Na2S2O3∙5H2O) and sulphuric acid (H2SO4 ). The acid was used to adjust the pH of the bath. The deposited film was characterised using Surface Profilometer, X-Ray Diffractometer (XRD), Uv-Visible Spectrophotometer and four point probe technique. Surface profiling revealed that the film is continuous with thickness of about 60 nm. The XRD result showed that the film has orthorhombic crystal structure. Film's crystallite size was estimated as 0.61 nm and interplanar spacing as 0.29 nm. The Uv-visible Spectrophotometer result reveals that, the film has good absorbance but poor reflectance and transmittance in the visible light region. The film has direct allowed transition with energy band gap of 1.69 eV. Values of surface resistivity and conductivity were deduced from data obtained from Four-point probe studies as 5.12 x 10-4Ω-cm and 1.96 x 103Ω-1cm-1 respectively. The I-V characteristics curve of ITO/SnS/Ag structure is linear indicating an Ohmic contact between the substrate electrode and the deposited layer. It can therefore be suggested that the film can allow pathway for photoabsorption and also aid charge transfer in photovoltaic process. Keywords: tin sulphide, orthorhombic, electrochemical deposition, characterization, photovoltaic and surface resistivity.

Sintering behavior and microwave dielectric properties of CaTi1-x(Nb1/2Al1/2)xO3

CaTi1-x(Nb1/2Al1/2)xO3 with x=0.1-0.5 ceramics were processed through solid state sintering. X-rays diffraction (XRD) patterns of the compositions showed that the samples have orthorhombic crystal structure with symmetry (Pbnm). The symmetry was further confirmed using Raman spectroscopy. A total of 13 Raman modes were detected, which were in agreement with the XRD results. Microstructure analysis of the samples showed porosity in the samples, presumably due to the substitution of Al, having high melting point. As the concentration of Al and Nb increased, relative permittivity (er), quality factor (Q×fo) and temperature coefficient of resonance frequency decreased. Optimum microwave dielectric properties were achieved for the composition x=0.5 sintered at 1650 °C for 8 h i.e., er ~27.09, Q×fo ~17378 GHz and tf ~ -2.5 ppm/°C.

Progress in fabrication and characterization of mullite whiskers

Mullite has an orthorhombic crystal structure, with various advantages, such as high mechanical strength, and stable chemical and physical properties. Especially, mullite whiskers have been widely acknowledged to be potential candidates as reinforcing elements in the fabrication of ceramic-matrix composites. Various strategies have been developed to synthesize mullite whiskers, such as catalytic methods, liquid-phase reaction, molten salt reaction, solid-state reaction and high-energy ball milling process. In different synthesis methods, the underlying mechanisms governing the anisotropic grain growth of mullite grains vary. This paper aims to offer an overview on the progress in fabrication of mullite whiskers with different methods, and the perspectives on these special materials are briefly discussed.

Mechanical Properties Analysis of Medium Carbon Steel Heated at 850°C by Quenching in NaOH Solution

The aim of this study is to analyze the mechanical properties of carbon steel medium by quenching in NaOH solution. Heating medium of the carbon steel in a heating furnace is 850°C. The cooling process in NaOH solution was varied in concentration of NaOH (5%, 10%, 15%, 20%, 25%), and the sample was allowed to reach room temperature (27°C). The original medium carbon steel hardness value is 9.4 HRC and the tensile strength value is 656.85 MPa, while for materials with heat treatment processes and cooling processes with different concentrations of NaOH (5%, 10%, 15%, 20%, 25%) resulted in hardness values of 57 HRC, 58.3 HRC, 58.5 HRC, 60 HRC, 57.5 HRC and tensile strength values of 728.50 MPa, 835.99 MPa, 987.26 MPa, 1035 MPa, and 855 MPa for different concentrations of NaOH (5%, 10%, 15%, 20% , 25 %). Analysis of XRD crystalline structure on medium carbon steel with intermediate carbon steel from the three highest peaks of each test sample was found that its orthorhombic crystal structure in which lattice parameters a, b, and c.

Synthesis and Characterization of SILAR-Deposited Leaf-Like Copper Sulphide Films

Successful synthesis of copper sulphide films deposited via successive ionic layer adsorption and reaction (SILAR) method at 100, 150, and 200 cycles. The deposited films were characterized for their morphological, structural, elemental, optical, and electrochemical features. A leaf-like morphology was obtained for the CuS films. Orthorhombic crystal structure with distinct peaks at (262) and (116) planes were observed. Good optical features, high absorbance with band gap energies ranging from 1.95 eV to 1.98 eV. The synthesized films possessed good electrochemical features with supercapacitive abilities. The synthesized materials find potential applications in optical devices and supercapacitors.