Traces of water can profoundly alter the dielectric response of functional oxides, yet such effects have remained largely unrecognized in systems where colossal dielectric behaviour has been widely reported. Here, we investigate the impact of sub-percent hydration (<1 wt%) on the dielectric relaxation, charge transport, and interfacial polarization properties of porous BiFeO_3 ceramics. Broadband dielectric spectroscopy reveals, in the hydrated state, a dominant relaxation process characterized by an anomalously large dielectric strength (Δε≈ 10^4-10^5) and a pronounced saddle-point deviation from Arrhenius dynamics, indicative of non-Arrhenius relaxation behaviour in a porous oxide system. These features appear only in the hydrated state and vanish upon dehydration, while the intrinsic activation barriers governing the thermally activated relaxation timescale remain comparable. Comparison with hydration-controlled dielectric responses in layered clay minerals shows that similar qualitative deviations can emerge in BiFeO_3 with nearly fifteen-fold lower water content, underscoring the effectiveness of confined water at grain boundaries, pore surfaces, and internal interfaces. Together, these results demonstrate that trace, confined water can make a major extrinsic contribution to dielectric and transport anomalies in porous oxide ceramics. The use of dehydration-controlled dielectric cycling provides a practical diagnostic framework for reassessing colossal dielectric responses, Maxwell-Wagner-type effects, and hydration-induced phenomena in functional oxide materials.

ZnO-Bi2O3 based varistors are prepared by solid-state sintering and defect dynamics in the varistors under AC and DC stress are investigated using dielectric spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. By combining experimental evidence, we find that the dynamics of the occupation of the interface states by electrons is influential in ZnO varistors under AC stress and at the early stage of DC stress, which has not been noticed before. The process is beneficial to the enhancement of electrical properties of varistors by modifying double Schottky barriers at grain boundaries. After 302 h of AC stress, the breakdown field (EB) increases from 236.2 V/mm to 248.7 V/mm and the leakage current density (JL) decreases from 0.062 mu A/cm2 to 0.025 mu A/cm2. After 184 h of DC stress, in the same direction as the stress E B increases from 235.2 V/mm to 243.7 V/mm and J L decreases from 0.065 mu A/cm2 to 0.059 mu A/cm2.

GaN High-Electron-Mobility Transistors have gained some foothold in the power-electronics industry. This is due to wide frequency bandwidth and power handling. Gallium Nitride offers a wide bandgap and higher critical field strength compared to most wide-bandgap semiconductors, resulting in better radiation resistance. Theoretically, it supports higher speeds as the device dimensions could be reduced without suffering voltage breakdown. The simulation and experimental results illustrate the superior performance of the Gallium Nitride High-Electron-Mobility Transistors in an amplifying circuit. Using a spice model for commercially available Gallium Nitride High-Electron-Mobility Transistors, non-distorted output to an input signal of 200 ps was displayed. Real-world measurements underscore the fast response of the Gallium Nitride High-Electron-Mobility Transistors with its measured slew rate at approximately 3000 V/μs, a result only 17% lower than the result obtained from the simulation. This fast response, coupled with the amplifier radiation resistance, shows promise for designing improved detection and imaging circuits with long Mean Time Between Failure required, for example, by next-generation industrial-process gamma transmission-computed tomography.

Cr-doped ZnO films were fabricated by a new but feasible method, that is, annealing Cr-Zn layers deposited via DC magnetron sputtering in air. Microstructures of the films were investigated using X-ray diffraction, scanning electron microscopy, and atomic force microscopy, intrinsic point defects were identified via photoluminescence spectroscopy, and optical and dielectric properties were analyzed using a UV-vis spectrophotometer and dielectric spectrometer, respectively. It was found that the average grain sizes decrease (56.34 - 39.50 nm), the band gap increases (from 3.18 to 3.23 eV), and the transmittance (at 600 nm) decreases (from 91

Bismuth ferrite (BiFeO_3, BFO) is a promising multiferroic oxide whose practical utilisation is limited by secondary-phase formation and defect-driven electrical inhomogeneity within the Bi_2O_3-Fe_2O_3 system. In this work, BFO was synthesised via solid-state reaction using 55:45 and 70:30 (mol

Modern microelectronic systems require long term operational stability, necessitating precise reliability models to predict device lifecycles and identify governing failure mechanisms. This is particularly critical for high power GaN High-Electron-Mobility Transistors (HEMTs), where reliability research has historically trailed behind low power digital counterparts. This study introduces a novel application of a modified boost converter circuit designed to investigate GaN failure mechanisms, specifically targeting the determination of reliability factors for the MTOL model. By utilizing a high duty cycle, the circuit stresses the device at maximum rated voltages and currents with minimal input requirements, accelerating hot carrier and trap generation without immediate detrimental failure. Experimental validation was conducted using an EPC 2038 GaN transistor under a constant drain current of 400 mA and a duty cycle of 0.7. The results confirmed that the increase in Drain-Source on-resistance (R_DS(on)) follows a logarithmic trend over time, consistent with the EPC Phase 12 reliability model. While initial tests at 40V did not successfully validate the longitudinal optical phonon scattering energy (_LO), but were reasonably acceptable, subsequent stress tests at 70V and 100V yielded _LO values that were successfully validated against existing theoretical and experimental data. This methodology provides a robust framework for predicting performance and lifetime across varying operational parameters in modern power electronics.

The recent return of the US to the Paris Climate Accord, massive increase in solar panel production and energy storage solutions has resulted in pressure on supply for solar cell materials and recycling of panels installed in the 90's and beginning of the 2000's which have reached their end of life. In this work we focus on recycling silicon wafers and dies by stripping previous structures from the die using potent acids after which its base material is characterized and binned. We demonstrate the process for silicon p-type substrates where n-type doping is attained by using a simple solution of phosphoric acid, which is diffused into the substrate using a furnace thus creating a PN junction. In case the substrate is n-type it could be replaced by boric acid. This is followed by deposition of a conductive antireflective coating, bus bars and rear wafer metal coating. The initial demonstrated laboratory results indicate the feasibility of recycling wafers using simple low cost standard industrial methods.

Aluminum single crystals are tested using X-Ray Bragg diffraction, which may have applications in microscopy and electronics fabrication industry. Yet, their efficiency for x- ray beam diffraction depends on the accurate crystal orientation, the microstructure and imperfections. Moreover, the final sample that is formed from the as-grown crystal by cutting, grinding, polishing and chemical etching, introduces various surface defects that penetrate deep into the crystal affecting its natural structure. Defect penetration is attributed to the fact that ultra-pure aluminum single crystals are soft and ductile with a hardness in the range of 2~2.5 mho. This leads to lattice deformation, resulting in a deviation from the crystallographic orientation of the final device, affecting the diffraction intensity and an apparent shift in the Bragg angle. In this work we investigate the influence of processing aluminum single crystals by mechanical and chemical means using XRD and Rocking-Curve broadening as a quantitative indication concerning the depth of the damage. This is a preliminary step in supporting future work on the study of electrical conduction in aluminum single crystals. Supplementing electrical conductivity measurements of aluminum, quality assessment of defects in front cell aluminum conductors can assist in designing novel low resistance aluminum conductors replacing the currently widely used and relatively rare silver.

The complex dielectric permittivity of a sintered ceramic tablet consisting of 70.5 % BiFeO3 and 27.7% Bi2Fe4O9 was analyzed as a function of temperature from -120 °C to 230 °C. The results reveal a complicated dielectric response with temperature activated relaxation features. They also reveal a ferroelectric phase transition that decayed with repeated heating cycles of the tablet. The source of the behaviour is assigned to relaxation processes happening along the grain boundaries of differing compositions in the tablet. The origin of the phase transition is traced to locally induced strains on grain boundaries because of unit cell size mismatch between BiFeO3 and Bi2Fe4O9.

Ceramic $BiFeO_{3}$ samples were prepared by rapid sintering at $880^OC$. Two compositions were examined. A $56/44\ Bi_{2}O_{3}/Fe_{2}O_{3}\ mole\%$ composition and a $56Bi_{2}O_{3}\cdot44Fe_{2}O_{3}+6.5wt\%\,NaCl$ composition. The samples were heat treated at different times up to $8$ minutes and the phase content was examined as a function of the time using XRD measurements and analysis. It was demonstrated that using both compositions, maximum $BiFeO_{3}$ phase content is obtained after $3.5$ minutes. In the former approximately $50\%$ of the material transformed to $BiFeO_{3}$ while in the latter $98.5\%$.

Electropolishing has found wide application as the final surface treatment of metal products in mechanical engineering and instrumentation, medicine and reflective concentrators for PV cells. It was found that electropolishing (EP) not only reduces the surface roughness and changes its appearance, but improves many operational characteristics as well, such as corrosion resistance, endurance, tensile strength, and many others, and also changes the physicochemical properties, for example, reflectivity, electromagnetic permeability and electronic emission of some ferro-magnetic metals. This fact greatly expands the possibility of using this method in various fields of science and technology. This work is part of a study, examining electro polishing for reducing the crystalline defects adjacent to the surface, thus improving its physical properties, contributing to higher optical efficiency, when used in PV generation and storage devices. Five compositions were examined using different temperature and current density parameters. The polished samples were evaluated using reflectance spectrometry. The solution which was composed of Phosphoric acid 85%, Acetic acid 10%, Nitric acid 5% was found to provide the best results. Another result obtained was that reflectance increased as the current density increased up to 25 A/dm2. Further increasing the current density resulted in deterioration of the surface and reduced reflectance. It was shown that careful lapping and polishing followed by electropolishing using the suggested solution may consist of an adequate treatment for preparing reflective concentrators for PV cells.

GaN high electron mobility transistors (HEMT) have gained some foothold in the power electronics industry due to wide frequency bandwidth and power handling. The material offers a wide bandgap and higher critical field strength compared to most wide bandgap semiconductors, resulting in better radiation resistance and theoretically higher speeds as the devices dimensions could be reduced without suffering voltage breakdown. This work consists of the underlying simulation work intended to examine the response of the GaN HEMTs preamlifying circuits for high resolution high energy radiation detectors. The simulation and experimental results illustrate the superior performance of the GaN HEMT in an amplifying circuit. Using a spice model for a commercially available GaN HEMT non distorted output to an input signal of 200 ps was displayed. Real world measurements underscore the fast response of the GaN HEMT with its measured slew rate at approximately 3000V/μs a result only 17% lower than the result obtained from the simulation.

A low-cost time domain system for measuring dielectric relaxation in the frequency range of 1 Hz–1 MHz of solid and molten materials at high temperatures is described in detail. A parallel plate electrode sample cell is described that can hold molten material by capillary action. In order to avoid electrical breakdown or a change in electrode distance due to opposite charge buildup, the step voltage can be set to the mV range. At this level interference noise affects the measurements and active filtering is required. The resulting signal is captured using a digital storage oscilloscope. An algorithm for reducing the measured data prior to data processing is discussed. The system is calibration free and its upper temperature is limited only by the construction materials of the furnace and electrodes. Molten NaCl is presented as a test sample.

A low-voltage (mV) electronically triggered spot welding system for fabricating fine thermocouples and thin sheets used in high-temperature characterization of materials' properties is suggested. The system is based on the capacitance discharge method with a timed trigger for obtaining reliable and consistent welds. In contrast to existing techniques based on employing high voltage DC supplies for charging the capacitor or supplies with positive and negative rails, this method uses a simple, standard dual power supply available at most of the physical laboratories or can be acquired at a low cost. In addition, an efficient and simple method of fabricating non-sticking electrodes that do not contaminate the weld area is suggested and implemented.

Volume phase gratings have been fabricated by controlled generation of periodic striations during the growth of copper doped potassium lithium tantalate niobate crystals. Gratings with periods ranging from below 1 to 5μm were fabricated. It is shown that the fabricated composition grating induces a refractive index grating which is a superposition of a fixed grating and an electrically controlled (electrooptic) grating. The electrooptic grating is produced due to the generation of a spatial modulation of the Curie temperature which is manifested as a correlated modulation of the static dielectric constant. It was also observed that when operated at the immediate vicinity of the phase transition temperature the diffraction efficiency from these gratings was bi-stable at a specific electric field due to an induced shift of the Curie temperature.

Non-volatile electroholographic diffraction gratings were fabricated by periodically modulating the composition of KLTN crystals. The gratings are manifested as periodic variations of the static dielectric constant which are electrically induced into birefringence gratings.

New medical graduates in the UK are known as Preregistration House Officers (PRHOs). At the end of this first postgraduate year, the Postgraduate Dean is responsible for allowing the PRHO to be fully registered with the General Medical Council. During the period 1999-2002 Professor Miriam Friedman Ben-David designed a more robust approach to appraisal and assessment of PRHOs, which provided educational feedback to all trainees, allowed any poor performers to be detected at an early stage, and provided 'hard' observable evidence for certification decisions. This paper describes the more recent development of her work resulting from further piloting of her system. The key tool, a 360 degrees diagnostic questionnaire, is designed to identify strengths and weaknesses in individual performance. It is presently being used as a screening tool to identify any trainees needing additional support and further assessment. The tool also forms part of an evidence trail for all PRHOs and helps inform formative assessment as well as contributing, along with other evidence, to full registration decisions. The evaluation of this tool, also described in this paper, shows the feasibility of implementing such a system on a wider scale and illustrates the successful balance made between robustness and feasibility.

Off-centered top-seeded solution growth (TSSG) method is demonstrated as an effective and simple way to generate controlled composition modulation in potassium lithium tantalate niobate (KLTN) single crystals. The changes in concentration were measured by differential interference contrast (DIC) microscopy. Large length with periodic modulations ranging from 1 to 5μm in period was grown along a KLTN sample with period dispersion lower than 2%.