Papers by Keyword: Electrical Properties

Abstract: The study presents electrical performance metrics, especially, electrical resistivity, of aluminium based foams. They were fabricated by melt processing with cheap CaCO₃ blowing agent and compared to those produced commercially with an expensive TiH₂. Relatively ductile Al1Mg0.6Si alloy and high strength Al6Zn2.3Mg alloy comprising brittle eutectic domains were employed as matrix alloys for carbonate foams manufacture, whereas only aluminium was used for production of hydride foams. The important difference concerns test method procedure employed for measuring the electrical properties of the foams. The novel system equipped by novel instrument GOM 805 was developed and used for direct determination of electrical resistivity of the foams. In contrast, the known measurement of a thick metal foam sheet resistivity concerns a routine four-point probe technique. The specific electrical resistivity obtained for the experimental foams was compared and discussed with the published data of the foams manufactured by melt processing with TiH₂ of trade name Alporas^Ò and prepared by powder metallurgical technique with trade mark Alulight^Ò.It was established after comparative study that the present porous samples exhibit higher values of specific electrical resistivity then available in the market that may provide wider engineering application of the studied foams.

Abstract: Preparing of Sb₂S₃ precursor by sol gel method and the post selenization is a simple and low-cost method for preparing Sb₂(S, Se)₃. In the preparation process of this method, the number of spin-coating of Sb₂S₃ precursor determines the film thickness, structure, and S/Se ratio. In this work, the effects of different spin-coating times (1 to 5) on the structure, optical and electrical properties of the film were studied. The results showed that when the number of spin-coating increased from 1 to 5, the thickness of the film increased from 0.24 μm to 1.17 μm. When spin-coating twice, the strongest diffraction peak of the film changed from (120) to (230); as the spin-coating frequency continued to increase, the film gradually exhibited Sb₂S₃ characteristics, accompanied by a small amount of Sb₂O₃ impurities. In addition, excessive spin-coating cycles can cause large voids to appear on the surface of the film. From the UV-visible spectrum, it can be seen that as the thickness of the film increases, the light absorption also gradually improve, and the band gap increases from 1.34 eV to 1.66 eV. The Mott-Schottky test showed that the prepared thin films were all P-type semiconductor. When spin-coated twice, the carrier concentration of the thin film reached 5.8×10¹⁵cm^-3.

Abstract: We report on an approach for the in-situ synthesis (chemical method based) of SnO-SnO₂ nanocomposites followed by characterisation (including morphological, chemical, structural and optical) and investigation of the electrical properties of the nanocomposites with reference to the as-synthesized SnO₂ nanoparticles. Compared to spherical SnO₂ particles, the SnO phase is found existing in the form of sheet like morphology. It has been found that through controlling of the Sn:OH precursor ratio is effective for the achievement of SnO phase. Compared to the pristine SnO₂ nanoparticles, the current-voltage (I-V) characteristics of the nanocomposites show the p-n junction characteristics. The observation of rectification ratio 2.05 indicates the excellent rectifying property of the nanocomposites due to the presence of p-type SnO phase. Further, exploration of the I-V characteristics has revealed the dominance of space-charge limited current transport mechanism for the nanocomposites sample. The lattice defects are discovered to be the cause of the transport mechanism in the nanocomposites sample.

Abstract: Copper Zinc Sulfide Cu_xZn_yS (CZS) thin films with different thicknesses were prepared by the ultrasonic spray pyrolysis method (USP). The influence of deposition time on the structural, morphological, and optical properties of the thin films has been investigated. XRD styles revealed the formation of ternary CZS films. Synchrotron X-ray diffraction measurements confirmed the presence of the two phases CuS and ZnS, which form the ternary compound CZS. Crystallite size increases from 75.29 nm to 105.46 nm as deposition time increases whereas the strain parameter decreases from 6.27*10^-4 to 3.28*10^-4. The obtained SEM images show that CZS thin films have a dense and rough surface topography. Spectrometric analysis of the deposited films confirmed the alloy nature of the elaborated films, whereas the corresponding values of band gaps were in the range of 3.28 to 3.17 eV. Results show that increasing the deposition time enhances the optical properties. Furthermore, the electrical properties of CZS films are influenced by the deposition time and phase transition. Significant improvements on these properties were obtained when the thin film thickness increased: the resistivity decreased from 95.10 to 0.12 Ω cm the carrier centration increased from 4.03×10²¹ to 14.07×10²¹ cm⁻³ and the mobility varied from 0.83 to 18.75 cm² V⁻¹ S⁻¹.

Abstract: The synthesis of ceramic composites consisting of cerium and titanium-doped zirconium (ZCT) oxide was achieved by the solid-state reaction technique. The ZCT composite ceramic powder undergoes sintering at various temperatures, including room temperature (RT), 1000°C, 1100°C, 1200°C, and 1300°C. Extensive study has been conducted on ceria-based materials in the field of catalysis, owing to their vast array of uses. Nevertheless, there was a limited amount of research conducted on the impact of ceria in the solid-state reaction approach. The current study employed a solid-state reaction method to fabricate ceramic composites comprising ZrO₂, CeO₂, and TiO₂. Various sintering temperatures were employed in the process. This study aimed to evaluate the impact of the sintering effect of ZCT ceramic oxides on several aspects, including crystal structure, surface morphology, optical properties, and electrical properties. The ZCT ceramic oxide underwent sintering at room temperature (RT), 1000°C, and 1100°C, resulting in the formation of a monoclinic crystal structure. However, sintering at 1200°C and 1300°C led to the presence of mixed phases, characterized by both monoclinic and tetragonal crystal structures, as observed through X-ray diffraction (XRD) analysis. When the sintering temperature is increased from 1000 to 1300°C, there is a modest drop in the band gap of a ZCT material from 3.43eV to 3.25eV. frequency(1mHZ-200kHz) dependence of dielectric constant, dielectric loss and ac electrical conductivity of the synthesized composites were carried out. The results indicate that dielectric constant and loss decreases with frequency rises and reaches a constant value at higher frequencies. The electrical conductivity of all ZCT samples exhibits an increase as the frequency is raised, whereas it reaches a minimum at lower frequencies.

Abstract: (1-x)BiFeO₃-xBaTiO₃-0.01KVO₃ with (x = 0.33 and 0.38) (abbreviated FTV33 and FTV38) was successfully prepared using three precursors that had been synthesized before the calcination process. BaTiO₃ was synthesized using the coprecipitation method, BiFeO₃ was synthesized using the sol-gel auto-combustion method, and KVO₃ was synthesized using the conventional solid-state method. Thermal analysis was carried out to determine the calcination temperature from 600 0C for 2h to 600 0C for 4h. X-ray diffraction (XRD) has been carried out to identify the phase after calcination at temperatures, respectively. The phase identification of the XRD pattern has been carried out by Match software shows that the powder and FTV33 and FTV38 have a pseudo-cubic structure with a P4mm space group and rhombohedral with an R3c space group. The XRD pattern is refined by the Rietveld method by Rietica software and the crystalline size is determined by MAUD software. The doping effect of KVO₃ on its electrical properties was systematically investigated and show that FTV33 is more conductive and has larger capacitance grains. Based on the previous XRD analysis, Ba²⁺ and K⁺ ions replaced Bi³⁺ at site A. On the other hand, Ti⁴⁺ and V⁵⁺ substituted Fe³⁺ at site B which was different from the host's oxidation state.

Abstract: Exploration of the optoelectronic memristor is required to investigate the photoelectric properties of materials. The traditional memristor material GeAs₂Te₄ is hopeful to be developed into a new type of optoelectronic memristor. However, acquiring high-quality single crystals remains challenging, and the electrical properties of single crystals of GeAs2Te4 need to be explored. Herein, a controlled method is introduced to grow reliable quality GeAs₂Te₄ single crystals, and the electrical and optoelectronic properties are studied. The photodetector based on GeAs₂Te₄ exhibits acceptable optoelectronic performance at designed low temperatures. The responsivity and detectivity of the GeAs₂Te₄-based photodetector reached the value of about 0.137 A W^-1 and 6.9×10⁷ Jones, respectively. It is promising to introduce this family of materials into the field of photodetector and also maybe further in the area of optoelectronic memristors.

Abstract: Indium tin oxide (ITO) thin films with 100 nm thickness were successfully deposited on soda-lime glass substrates by metal oxide electron beam evaporation at room temperature. The deposited films were post annealed via rapid thermal processor (RTP) in vacuum environment at 400 to 550 °C. All deposited ITO thin films were studied on the structural, electrical, and optical properties. Results showed that the post annealing treatment by RTP improved the crystallinity, increased crystallite size, and increased surface roughness values. Higher RTP post annealing temperature also enhanced the electrical performance that led to higher transmittance of ITO thin films.

Abstract: This paper reports on the successful synthesis of fine nanoparticles of nickel-substituted lithium-iron ferrites of composition Li_0.5-x/2Ni_xFe_2.5-x/2O₄ (0.2≤ x ≤1.0) by the sol-gel autocombustion method. It has been found that the alternating current (AC) and direct current (DC) conductivity is preferably tuned due to its dependence on temperature and nickel doping. Analysis of the Arrhenius dependences also confirms the appearance of more than one conduction mechanism upon substitution. The predominance of one type of conductivity over another depends on the concentration of the substituting element. Measurement of the magnetic properties has shown that the substitution of Ni²⁺ can significantly change the saturation and residual magnetization. Samples of composition Li_0.4Ni_0.2Fe_2.4O₄ have the highest saturation magnetization (84.08 emu/g), residual magnetization (15.85 emu/g), and the lowest coercive force (0.18 kOe). All the obtained results indicate a significant effect of the substitution of Ni²⁺ ions on the structure and properties of Li_0.5-x/2Ni_xFe_2.5-x/2O₄ ferrite nanoparticles.Photocatalytic properties have been obtained by the degradation of Methylene Blue dye under illumination with a halogen lamp. It is shown that an increase in the content of nickel ions leads to a change in the type of conductivity: from n-type (unsubstituted lithium pentaferrite) to p-type (with substitution x = 0.8 and higher). These systems are characterized by hopping conduction realized by octa-positions according to the mechanisms Fe³⁺+e^-↔Fe²⁺, and Ni³⁺↔Ni²⁺+h⁺. The predominance of one or another mechanism depends on the content of nickel ions. The optical band gap ranges from 1.4 to 2.25 eV. Samples with nickel content x = 0.4 and x = 0.8 have shown the best degradation ability, which is 97% within 160 min for Methylene Blue.

Abstract: In recent years, the materials industry has begun to develop in the directions on enabling the effect of nanomaterials. Nanomaterials are one of the most basic materials that have helped in the development of industrial technology because of their unique properties. These properties make them spread in many areas, especially in the electrical and thermal. Still, traditional materials, at present, suffer from issues that restrict their use, such as thermal conductivity and electrical conductivity. Currently, nanomaterials owing to outstanding performance those traditional materials do not possess. In contrast, scientists have recently focused their efforts on increasing the (electrical and thermal) applications of epoxy resins. In this study, we combined nanoparticles (CaTiO3) with type epoxy resin (Quickmast 105) with different concentrations of CaTiO₃ (0, 0.01, 0.02, 0.03, 0.04, 0.05 wt%) by casting. Several tests such as thermal conductivity, thermal expansion, electrical conductivity, dielectric constant and dielectric loss have been carried out. The test results showed a significant increase in thermal conductivity with increasing concentrations of nanoparticles in epoxy, decreasing thermal expansion by 28%, and increasing AC conductivity for all concentrations. The relative permittivity (dielectric constant) of epoxy nanocomposites remains nearly constant with increasing frequency. For dielectric loss, it can be seen that the epoxy nanocomposite's tan values are increasing also with high concentrations.