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Thermally stimulated current (TSC), thermally stimulated depolarization current (TSDC), and thermally stimulated luminescence (TSL) spectroscopies were combined to study trapping phenomena in undoped bulk SrTiO3 crystals. Electrical measurements were also performed and showed that the crystals are highly resistive in the dark but exhibited an unusually high photocurrent upon 400-nm illumination. Several traps were revealed in both TSC and TSDC spectra between 83 K and 450 K in such a broad temperature range and their activation energies were extrapolated from the trap positions (peaks). TSL spectra demonstrate similar characteristics comparable to TSC and TSDC spectra, though there are some differences because of different excitation and recombination mechanisms. This work reveals the presence of large number of traps in SrTiO3 single crystals, which are most likely the source of many of the interesting phenomena in SrTiO3 such as transient and persistent photoconductivity.

Despite being discovered more than 20 years ago, nanofluids still cannot be used in the power industry. The fundamental reason is that nano-insulating oil has poor stability, and its electrical performance decreases under negative impulse voltage. We found that C60 nanoparticles can maintain long-term stability in insulating oil without surface modification. C60 has strong electronegativity and photon absorption ability, which can comprehensively improve the electrical performance of insulating oil. This finding has great significance for the industrial application of nano-insulating oil. In this study, six concentrations of nano-C60 modified insulating oil (CMIO) were prepared, and their breakdown strength and dielectric properties were tested. The thermally stimulated current (TSC) curves of fresh oil (FO) and CMIO were experimentally determined. The test results indicate that C60 nanoparticles can simultaneously improve the positive and negative lightning impulse and power frequency breakdown voltage of insulating oil, while hardly increasing dielectric loss. At 150 mg/L, the positive and negative lightning impulse breakdown voltages of CMIO increased by 7.51% and 8.33%, respectively, compared with those of FO. The AC average breakdown voltage reached its peak (18.0% higher compared with FO) at a CMIO concentration of 200 mg/L. Based on the test results and the special properties of C60, we believe that changes in the trap parameters, the strong electron capture ability of C60, and the absorption capacity of C60 for photons enhanced the breakdown performance of insulating oil by C60 nanoparticles.

The effects of annealing treatment on the polarization of copolymer P(VDF-TrFE) free-standing films were thoroughly studied by the thermally stimulated current (TSC) method using decomposition analysis and first-order kinetic theory. The TSC measurement mainly revealed three depolarization peaks, which are known as the β, α and Curie mode (ρ) peaks in P(VDF-TrFE). The origin of the TSC peaks and their relaxation behaviour were correlated with structural, morphological and electrical properties such as ferroelectricity, dielectricity and pyroelectricity. Spin-coated copolymer thin films with thicknesses of 300 nm were also prepared from 5 wt.% solutions. Both free-standing and thin films were initially annealed in the range of their Curie temperature up to the melting point [80–140°C] to increase their crystallinity. A remnant polarization current of 76.7 mC m−2, which gives a pyroelectric coefficient of 31 μC m−2K−1 and a figure of merit FD of 86 μC m−2K−1 (1 kHz), was obtained from the sample annealed at 100°C, where the percentage of crystallinity was maximum and the phase was about to transition from ferroelectric to paraelectric.

In this article, the mechanism of relaxation polarization currents occurring at a constant temperature (isothermal process) in crystals with ionic-molecular chemical bonds (CIMBs) in an alternating electric field was investigated. Methods of the quasi-classical kinetic theory of dielectric relaxation, based on solutions of the nonlinear system of Fokker–Planck and Poisson equations (for the blocking electrode model) and perturbation theory (by expanding into an infinite series in powers of a dimensionless small parameter) were used. Generalized nonlinear mathematical expressions for calculating the complex amplitudes of relaxation modes of the volume-charge distribution of the main charge carriers (ions, protons, water molecules, etc.) were obtained. On this basis, formulas for the current density of relaxation polarization (for transient processes in a dielectric) in the k-th approximation of perturbation theory were constructed. The isothermal polarization currents are investigated in detail in the first four approximations (k = 1, 2, 3, 4) of perturbation theory. These expressions will be applied in the future to compare the results of theory and experiment, in analytical studies of the kinetics of isothermal ion-relaxation (in crystals with hydrogen bonds (HBC), proton-relaxation) polarization and in calculating the parameters of relaxers (molecular characteristics of charge carriers and crystal lattice parameters) in a wide range of field parameters (0.1–1000 MV/m) and temperatures (1–1550 K). Asymptotic (far from transient processes) recurrent formulas are constructed for complex amplitudes of relaxation modes and for the polarization current density in an arbitrary approximation k of perturbation theory with a multiplicity r by the polarizing field (a multiple of the fundamental frequency of the field). The high degree of reliability of the theoretical results obtained is justified by the complete agreement of the equations of the mathematical model for transient and stationary processes in the system with a harmonic external disturbance. This work is of a theoretical nature and is focused on the construction and analysis of nonlinear properties of a physical and mathematical model of isothermal ion-relaxation polarization in CIMB crystals under various parameters of electrical and temperature effects. The theoretical foundations for research (construction of equations and working formulas, algorithms, and computer programs for numerical calculations) of nonlinear kinetic phenomena during thermally stimulated relaxation polarization have been laid. This allows, with a higher degree of resolution of measuring instruments, to reveal the physical mechanisms of dielectric relaxation and conductivity and to calculate the parameters of a wide class of relaxators in dielectrics in a wide experimental temperature range (25–550 K).

Ceramic samples with compositions along the (1 – 2 x )BiScO 3 ·(2 – y ) x PbTiO 3 ∙ yx PbMg 1/3 Nb 2/3 O 3 ( y = 1.2, 1.0, 0.9, 0.5) sections in the BiScO 3 –PbTiO 3 –PbMg 1/3 Nb 2/3 O 3 (BS–PT–PMN) system have been characterized by X-ray diffraction and dielectric, piezoelectric, and thermally stimulated depolarization current measurements. The materials with 1 – x ≲ 0.5 have been shown to consist of perovskite solid solutions. With increasing BS content, the symmetry of the solid solutions rises from tetragonal to cubic. In the intermediate composition region (morphotropic region (MR)), the samples consist of a mixture of solid solutions differing in symmetry. We have located the MR boundaries and examined the effect of composition on the dielectric and piezoelectric properties of the solid solutions.

Surface charges on implants improve integration into bone and so require a clear protocol for achieving a surface charge and comparable results from different laboratories. This study sintered hydroxyapatite (HAp) at one laboratory to remove the influence of the microstructure on surface charge and then polarized/depolarized the pellets at two different laboratories (in Tokyo and Riga). Surface charges on HAp pellets induced by electric polarization at 400 °C in a 5 kV/cm DC electric field were measured by the thermally stimulated depolarization current (TSDC) method as 6–9 µC/cm2. The surface charge results were comparable between laboratories and also agreed with previously documented values. Recommendations describe conditions for polarization and depolarization to generate a surface charge and repeatedly achieve a comparable outcome. A visual display of the polarization mechanisms and the contribution to surface charge point to further aspects that need further development.

CdZnTe (CZT) ingots doped with different concentrations of indium (2 ppm, 5 ppm, 8 ppm, and 11 ppm) were grown by the Vertical Bridgman Method. The charge transport behaviors of CZT wafers were characterized by Thermally Stimulated Current (TSC), Time of Flight technique (TOF) and Current–Voltage measurements (I–V). TSC results indicate that the concentration of deep donor defects \\[ {\\hbox{Te}}_{\\rm{Cd}}^{{ 2 { + }}} \\] is reduced significantly by increasing indium dopant content from 2 ppm to 8 ppm, while that of indium related traps, \\[ {\\hbox{In}}_{\\rm{Cd}}^{ + } \\] and A-centers, is sharply increased. Hecht fitting and TOF results indicate that the electron mobility keeps nearly unchanged for different dopant concentrations in the region between 2 ppm and 5 ppm, but the lifetime increased greatly with increasing indium dopant concentration. Therefore, (μτ)e value was increased with higher indium dopant. The up-shift of Fermi level is also observed in the temperature-dependent I–V result with the increasing of indium dopant content. Large Schottky barriers are found in detectors with higher indium concentration. High voltage x-ray response results show that the channel number shifts to the low energy side for 2 ppm dopant samples compared with best performance 5 ppm dopant samples, while the full-energy peaks are broadened for 8 ppm and 11 ppm dopant samples.

Using the quasi-classical kinetic theory of dielectric relaxation, in addition to existing methods, fundamental mathematical expressions are built, which make it possible to more strictly consider the effects of the main charge carriers’ (protons’) tunneling on the numerical values of the molecular parameters (activation energy, equilibrium concentration) of protons in HBC. The formulas for calculating the statistically averaged non-stationary quantum transparency of a parabolic potential barrier for protons have been modernized by more stringent consideration of the effects of corrections caused by an external electric field. For the model of a double-symmetric potential well, a generalized nonlinear solution of the quasi-classical kinetic equation of dielectric relaxation in HBC was built. The phenomenological Bucci-Rive formula for thermally stimulated depolarization current density (TSDC) was first investigated, taking into account quantum transparency, for the case of a parabolic potential barrier. The choice of the parabolic shape of the potential barrier allowed, at a theoretical level, for the mathematical model of relaxation polarization to be brought closer to the conditions of the real spatial structure of the crystal potential field, in comparison with the rectangular potential barrier model. It has been found that quantum effects due to proton tunnel transitions significantly affect the mechanism of thermally stimulated depolarization currents in HBC, over a wide temperature range (50–550 K) and external field parameters (0.1–1 MV/m). Generalized solutions of the nonlinear kinetic equation, recorded considering the effects of field parameters on proton tunnel transitions, made it possible to significantly approximate the theoretical values of activation energies, equilibrium concentrations of protons and amplitudes of the theoretical maxima of the current density of thermally stimulated depolarization, according to their experimental values in the field of low-temperature (50–100 K) and high-temperature (350–550 K) maxima of TSDC density in HBC. For the first time, precision measurements of TSDC temperature spectra were carried out for chalcanthite crystals. The effects of alloying impurities concentrations and crystal calcination temperatures on the parameters of experimental maxima in the TSDC spectrum of chalcanthite were established. A physical mechanism of the quantum tunnel motion of protons in HBC with a complex crystal structure (crystalline hydrates, layered silicates, ferroelectric HBC (KDP, DKDP)) is described. The patterns found in this article indicate a fairly high degree of applied scientific significance for the obtained theoretical results, allowing for the further development of electrophysics and optoelectronics of heterogeneous structures (MIS, MSM) based on proton semiconductors and dielectrics (PSD) and their composites.

Practical application of crystals in optoelectronics and laser engineering requires the directions of optical axes and the types of oscillation centers be known, and this is an important and necessary condition. We have studied the infrared transmittance and absorption spectra of hexagonal lithium iodate α-LiIО 3 crystals grown by open evaporation method in H 2 O and D 2 O solutions and natural lamellar monoclinic crystals of phlogopite and muscovite. The band gap of the test crystals has been determined from the transmittance spectra. The absorption spectra have provided information on the activation energy and wavelength of the activation centers related to the oscillations of protons, hydroxonium ions Н 3 О + , protium Н + , ОН- groups and HDO molecules. There has been a good correlation between the parameters of infrared spectra, thermally stimulated depolarization current spectra and nuclear magnetic resonance spectra. We have analyzed the possibility of oscillation center diagnostics based on infrared spectra which also allow determining the directions of optical axes. The experimental results confirm the possibility of using IR spectra for determining the type of oscillation centers and the presence of lattice anisotropy in test crystals.

Silicon carbide (SiC) is widely used to improve the non‐linear conductivity of non‐linear resistive field grading composite. In this paper, the SiC nanoparticles are modified into core‐shell nanoparticles with silica (SiO2) coating on the surface and are characterised by transmission electron microscopy and X‐ray diffraction, respectively. The 7 wt% SiC@SiO2/epoxy nanocomposite is then prepared, and the pure epoxy and 7 wt% SiC/epoxy nanocomposite are prepared as a contrast. The relative permittivity, thermally stimulated current, conductivity and breakdown strength are studied, respectively. The presence of SiO2 shell around SiC nanoparticles has a great effect on the relative permittivity and trap distribution. The epoxy nanocomposites show non‐linear conductivity characteristics, compared with pure epoxy. The 7 wt% SiC@SiO2/epoxy nanocomposite has higher switching electric field and breakdown strength than the 7 wt% SiC/epoxy nanocomposite, which is helpful for the application of non‐linear resistive field grading composite in higher‐voltage equipment or components.