Frequency Dependence Of Dielectric Constant Research Articles

UV/Ozone-Treated and Sol-Gel-Processed Y2O3 Insulators Prepared Using Gelation-Delaying Precursors.

In this study, a Y2O3 insulator was fabricated via the sol-gel process and the effect of precursors and annealing processes on its electrical performance was studied. Yttrium(III) acetate hydrate, yttrium(III) nitrate tetrahydrate, yttrium isopropoxide oxide, and yttrium(III) tris (isopropoxide) were used as precursors, and UV/ozone treatment and high-temperature annealing were performed to obtain Y2O3 films from the precursors. The structure and surface morphologies of the films were characterized via grazing-incidence X-ray diffraction and scanning probe microscopy. Chemical component analysis was performed via X-ray spectroscopy. Electrical insulator characteristics were analyzed based on current density versus electrical field data and frequency-dependent dielectric constants. The Y2O3 films fabricated using the acetate precursor and subjected to the UV/ozone treatment showed a uniform and flat surface morphology with the lowest number of oxygen vacancy defects and unwanted byproducts. The corresponding fabricated capacitors showed the lowest current density (Jg) value of 10-8 A/cm2 at 1 MV/cm and a stable dielectric constant in a frequency range of 20 Hz-100 KHz. At 20 Hz, the dielectric constant was 12.28, which decreased to 10.5 at 105 Hz. The results indicate that high-quality, high-k insulators can be fabricated for flexible electronics using suitable precursors and the suggested low-temperature fabrication methods.

Computational dielectric spectroscopy on solid-solution interface by time-dependent voltage applied molecular dynamics simulation.

A frequency-dependent dielectric constant characterizes the dielectric response of a medium and also represents the time scale of system's collective dynamics. Although it is valuable not only academically but also practically for developing advanced devices, getting the value of a solution at the interface with a solid or electrode surface is challenging both experimentally and computationally. Here, we propose a computational method that imitates the dielectric spectroscopy and AC impedance measurement. It combines a time-dependent voltage applied molecular dynamics simulation with an equivalent circuit representation of a system composed of a solution confined between two identical electrodes. It gives the frequency-dependent dielectric constants of the bulk solution and the interface simultaneously. Unlike the conventional method, it does not require computation of a dipole autocorrelation function and its Fourier transformation. Application of the method on a system of water confined between polarizable Pt electrodes gives the static dielectric constant and the relaxation time of the bulk water in good agreement with previous simulation results and experimental values. In addition, it gives a much smaller static dielectric constant at the interface, consistent with previous observations. The outline of the dielectric dispersion curve of the interface seems similar to that of the bulk, but the relaxation time is several times faster.

Comparative analysis of machine learning models for predicting dielectric properties in MoS2 nanofiller-reinforced epoxy composites

This research investigates the dielectric properties of nano epoxy composites by incorporating various concentrations of MoS2 into epoxy resin. The study explores the impact of synthesized nanoparticles on undoped epoxy composites, specifically focusing on their potential applications in dielectric materials. The experimental synthesis and characterization of nanoepoxy composites typically involve time-consuming and expensive methods. This study compares five machine learning (ML) models—random forests, decision trees, extra trees, XGBoost, and gradient boosting—in order to predict the frequency-dependent dielectric constants in these composites under different nanofiller variations in order to address this challenge. To ensure robust model performance, training is carried out on different subsets of the dataset, ranging from 60% to 30%, while the remaining portions are reserved for testing purposes (40% to 70%). The main objective of the study is to assess the performance of each regressor technique using metrics such as adjusted R2 score, MSE, RMSE, and MAE, in which the ET regressor excels. The ET method demonstrates exceptional performance, achieving an adjusted R2 value of 0.9977 and 0.9912 for target variables ε′ and ε′′, respectively when tested with a size of 0.4. The findings underscore the potential of ML models for precise and efficient prediction of frequency-dependent dielectric constants of nanoepoxy composites with various concentrations of nanofillers, offering an alternative to time-consuming and expensive laboratory work.

Dielectric Relaxation and AC Conductivity of Fe-Doped Glassy Semiconductors: Role of Fe Doping on Relaxation Time

AC conductivity and dielectric parameters are supposed to be two noticeable parameters that ensure the applicability of present samples for electronic and other applications. Presently, Fe-doped glassy semiconductors were developed by melt-quenching route and characterized using FT-IR, SEM, EDAX and decoupling index for structural, morphological and elemental examinations. Frequency dependent dielectric constant, AC conductivity, dielectric loss at different temperatures have been explored in a wide frequency and temperatures ranges. Electric modulus formalism has been conceived asit can exclude the electrode polarization effect at low frequency regime and suggest the transition from long-range mobility to short-range mobility assembly of polarons. It is also noteworthy that relaxation times are found to decrease with temperatures, which may indicate about the faster movement of charge carriers. The variation of KWW parameters directly indicate that after doping of Fe content into the resultant materials, the relaxation process is shifted from Non-Debye to Debye type up to a limit. By crossing the limiting value of composition (x = 0.3), it becomes Non-Debye type in a very slow rate. The present system also exhibits a small relaxation time in comparison with others’ works. Lower values of dielectric constant at high frequencies are expected to be important for their applications in photonics and opto-electronics. Scaling method of electric modulus spectra indicate that the dielectric relaxation process in the present system leads to a common relaxation process at various temperatures, but it is strongly dependent on compositions.

Random Forest Regression Analysis for Estimating Dielectric Properties in Epoxy Composites Doped with Hybrid Nano Fillers

Bisphenol-A resin epoxy resin composites doped with various concentrations of inorganic hybrid nanofillers, TiO2 + ZnO, were thoroughly examined in the research described in this report for their microwave dielectric relaxation spectroscopy. Ultrasonic dispersion techniques were used to disperse the TiO2 + ZnO hybrid nanofiller into the Bisphenol-A resin. X-ray diffraction (XRD) was employed to ascertain the structural characteristics of the TiO2 and ZnO nanoparticles (NPs) and TiO2 + ZnO hybrid NPs doped neat epoxy (epoxy + hardener). A Vector network analyzer was used to measure the dielectric properties of the hybrid NPs doped neat epoxy in the frequency range from 200 MHz to 20 GHz. Our findings offer important new perspectives on the polarization mechanisms and structural properties of these composite materials. The complex relationship between frequency and dielectric characterization led to measurement complexities that often come with extensive time and cost requirements. This paper presents the random forest regression model as an effective method for predicting the frequency-dependent dielectric constants in composite materials. The main objective of this study was to examine the performance metrics, such as the adjusted R-squared score, root mean squared error (RMSE), and mean absolute error (MAE), across various values of the minimum node size parameter (n min). This study showcases the effectiveness of the RF regression model to accurately and efficiently predict the frequency-dependent dielectric constants in composites. As a result, it eliminates the requirement for laborious and expensive laboratory testing.

Properties of Rubidium-Doped Potassium Titanyl Phosphate (Rb: KTP) Grown by Hydrothermal Method

As an electro-optical crystal with excellent properties, potassium titanyl phosphate (KTP) has high conductivity limits electro-optical applications. In this experiment, Rb-doped KTP crystals were grown by the hydrothermal technique of micro-doping and sustained-release, the crystal structure was determined by XRD, the presence of Rb in the crystals was explored by EDS, and the role of Rb in the crystals was investigated by Raman technique. Frequency-dependent dielectric constants were studied at room temperature, which decreases sharply at low frequencies. The variation of the conductivity of the crystals at different temperatures was investigated, and it was found that the room temperature conductivity of the KTP crystals, which were micro-doping by large ionic, was able to drop to 10−13 S/cm, which is about two orders of magnitude lower than that of the pure KTP crystals.

Rare earth Gd3+ substituted on cobalt ferrites: Structural and dielectric studies by citrate gel autocombustion method

Gadolinium-doped cobalt ferrite (CoGdxFe2-xO4; X = 0–0.025 in a 0.005 interval) was synthesised using citrate gel autocombustion. The effect of Gd3+ ions on structural, dielectric, and magnetic characteristics has been investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, ultraviolet visible spectroscopy (UV), an impedance (dielectric) analyzer, and a vibrating sample magnetometer (VSM) were used to characterise the as-synthesised materials. X-ray diffraction powder patterns were used to confirm phase identification and spinel structure, and the Williamson-Hall plot was used to investigate the crystalline size and lattice strain on the peak broadening of each sample, with crystalline size ranging from 13 to 48 nm. The scanning electron microscopy (SEM) micrographs demonstrate particle agglomeration, while energy dispersive spectroscopy (EDAX) pictures indicate the purity and existence of all elements in the created material samples. The frequency-dependent dielectric constant, dielectric loss, and AC electrical conductivity in the frequency range 50 Hz–1 MHz. The behaviour of dielectric properties has been studied using the Maxwell-Wagner model and Koop's theory. Because of this, higher frequencies show less dielectric loss, making them appropriate for use in high-frequency device applications.

The Role of Rubrene Concentration on Dielectric Parameters of Nematic Liquid Crystal

In this study, the dielectric parameters of E7 coded nematic liquid crystal (NLC) composites containing the different amounts of rubrene fluorescent dye were investigated. E7, E7+0.5 wt.% Rubrene, and E7+1.0 wt.% Rubrene samples were prepared. Frequency dependent dielectric constants (ɛ′ and ɛ′′), dielectric anisotropy (Δε′), and ac conductivity (σac) graphs of rubrene doped E7 NLC composites were obtained by dielectric spectroscopy method and compared with pure E7 NLC. By using these graphs, relaxation frequency (fR), relaxation time (τR), dielectric strength (δɛ′), and crossover frequency (fc) parameters of the E7 NLC and its rubrene doped composites were determined. An increase in fR from 3.045 MHz to 3.697 MHz for 0 V and from 627 kHz to 686 kHz for 40 V was observed with increasing rubrene concentration. On the other hand, a decrease in τR from 0.052 μs to 0.043 μs for 0 V and from 0.254 μs to 0.232 μs for 40 V was seen with increasing rubrene concentration. Furthermore, an increase in fc from 1.145 MHz to 1.298 MHz was obtained with increasing rubrene concentration. The results show that the dielectric parameters change with the concentration of rubrene and it is thought that this study will provide a basis for investigating the dielectric properties of rubrene doped NLC composites. Moreover, it is concluded that the produced composites are a suitable base material for electro-optical device applications such as smart displays, photonics and electrical circuit elements.

The Effects of Solvent Dynamics on the Back Reaction of Solar-Thermal Energy Storage Systems.

We have investigated dynamic solvent effects on molecular solar-thermal energy storage systems using models describing the effects of frequency dependent viscosities and dielectric constants on chemical reaction rates. We have utilized the generalized Langevin model for understanding how the reactions are affected by the frequency dependent viscosities and dielectric constants. Our results show that the rate constants of the molecular solar-thermal energy storage systems depend strongly on the dielectric electric solvent properties and the frequency dependent viscosities of the solvents.

Compositional effects of Ga incorporation on electrical and dielectric parameters in Ge-Se-Sb-Ga thin films

In this paper, the existence of new selenium-rich chalcogenide glassy systems i.e. (Ge20Se80)90-xSb10Gax (x = 2, 4, 6 and 10 at %) had been reported. (Ge20Se80)90-xSb10Gax glassy systems were prepared using melt-quenching technique. Thin films of (Ge20Se80)90-xSb10Gax were prepared on properly cleaned glass substrates using vacuum evaporation technique. Planar geometry of indium (In) electrodes (electrode spacing 0.08 cm) was used for electrical measurements. The physical parameters – average number of constraints, cohesive energy, mean bond energy, average coordination number, heat of atomization, glass transitition temperature and lone pair electrons had been estimated. The high values for the lone pair electrons proves the investigated system to be a good glass former. The increasing values of cohesive energy, glass transition temperature and mean bond energy with the incorporation of Ga, reveal that Ge-Se-Sb-Ga glassy systems are thermally stable glasses. The current transport mechanisms had been studied within the temperature range 173–363 K. Thermionic emission dominated in the high temperature region above 333 K. Within the intermediate temperature range 273–333 K, thermally-assisted tunneling of the charge carriers through grain boundary potential as well as thermionic emission over grain boundary potential contributed to the conduction mechanism. Below 273 K, Mott’s hopping process dominated the conduction mechanism. Dielectric measurements had been examined within the temperature range 173–363 K and the frequency range 50 Hz–1 MHz. Dielectric constant as well as dielectric loss decreased as the frequency was increased and increased as the temperature was increased. Orientation polarization described the temperature-dependence and frequency-dependence of dielectric constant. Temperature-dependence and frequency-dependence of dielectric loss was explained by conduction loss as well as hopping of charger carriers. The ac conductivity agrees with the power law: ωs where s < 1. The present investigation of dielectric parameters could be explained in terms of correlated barrier hopping (CBH) model. Profound analysis of the physical, electrical and dielectric properties and their variation as a function of Ga-content suggest the utilization of these glasses in optoelectronic devices.

Structural, morphological and frequency dependent dielectric properties of [formula omitted][formula omitted]) nanoparticles prepared by sol-gel method

In this work, the spinel ferrite NixZn0.6−xMn0.4Fe2O4(x=0.0,0.1,0.2,0.3,0.4) nanoparticles (NPs) have been synthesized via the sol-gel method. It is observed that the presence of Ni2+ ions cause an appreciable change in the different properties of the Ni substituted Zn0.6−xMn0.4Fe2O4 NPs. The Fourier transform infrared (FTIR) spectroscopy analysis confirms the formation of the NixZn0.6−xMn0.4Fe2O4 spinel structure. Rietveld's refinement of X-Ray Diffraction (XRD) patterns confirms the single-phase cubic spinel structure belonging to the Fd3m space group. The estimated lattice constant is found to decrease with increasing Ni contents except for x=0.1 and the average crystallite size varies from 6.7nmto100nm due to the reduction of grain growth upon Ni2+ occupation in the octahedral site. Frequency-dependent dielectric constant, dielectric loss, AC resistivity, and conductivity of the compositions have also been examined at room temperature. The ac resistivity exponentially decreases with the increase of frequency due to the effect of multilayer capacitance. Conversely, the ac conductivity is observed to increase exponentially with the frequency due to increased hopping between metallic cations Fe2+ and Fe3+. The electrical charge conduction behavior and contribution of grain and grain boundary resistance have been explained using Nyquist/Cole-Cole plot. Hence, the Ni doped Zn0.6−xMn0.4Fe2O4 NPs excellent dielectric behavior can be used for various potential applications including the fabrication of the nano-electronic device and multi-layers chip inductors applications.

Influence of the A-site cation on structural, morphological, magnetic, optical and transport properties of R2CoMnO6(R = Nd, Y, Ho and Er) double perovskite oxides

The A-site substituted double perovskite oxides (DPOs) have in the recent decades gained much attention due to their various interesting properties and possible applications. For this reason, R2CoMnO6 (R = Nd, Y, Ho, and Er) DPOs have been synthesized using the auto-combustion sol-gel method. X-ray diffraction analysis suggests the crystal structure, i.e., monoclinic for all under-investigated DPOs at room temperature (RT), consisting of space group P2 1 /n which is confirmed by Rietveld refinement. Crystallite size is calculated using Scherrer and Williamson-Hall methods, and it was found that the crystallite size decreased with decreasing ionic radii from 55–29 nm on average. The micrographs were obtained by using a field-emission scanning electron microscope (FE-SEM), which reveals an almost homogeneous distribution of grains throughout the surface of all DPOs. All observed infrared and Raman active phonon modes have been assigned to vibrations of atoms and groups of atoms consistent with the prediction of group theory. The intermediate band gap values (1.34–1.63 eV) determined by the Tauc relations suggest the semiconducting nature of these DPOs which makes them promising materials for photovoltaic applications. Dc electrical resistivity and dielectric measurements also suggest semiconducting behaviour above ambient temperature, which is attributed to a small polaron hopping conduction mechanism. The Maxwell-Wagner type interfacial polarization has described the nature of the frequency-dependent dielectric constants in these DPOs. The dielectric (ac) study also suggests the small polaron hopping conduction mechanism in all samples, which supports our findings in resistivity measurements.

Electric characterization of transition metal (Co, Ni, Fe) doped ZnO thin layers prepared by atomic layer deposition

Doping of ZnO with different ions enables efficient control of its optical, electrical and magnetic properties. ZnO thin films doped with 3d transition metals have potential to be used as diluted magnetic semiconductors. In this work, dielectric and electrical properties of transition metal (Ni-, Co- or Fe-) doped ZnO thin films prepared by atomic layer deposition (ALD) have been studied. Standard capacitance-voltage (C-V) and current-voltage (I-V) as well as capacitance-frequency (C-f) characteristics have been measured. Some important parameters, e.g. the concentration of majority carriers N D, barrier height Ф b as well as the built-in potential Vbi are determined. Different polarization effects are considered to explain the strong frequency dependence of dielectric constant.

Correlation between Cation Distribution and Magnetic and Dielectric Properties of Dy3+-Substituted Fe-Rich Cobalt Ferrite.

Designing electromagnetic materials, particularly those based on transition-metal-containing spinel ferrites, with a controlled structure, phase, and chemistry at the nanoscale dimensions while realizing enhanced electrical and magnetic properties continues to be a challenging problem. Herein, we report on the synthesis and structure-property correlation of dysprosium (Dy)-substituted iron-rich cobalt ferrite (Co0.8Fe2.2-xDyxO4; CFDO; x = 0.000-0.100) oxides with variable Dy3+ concentration. Chemical bonding analyses of CFDO nanomaterials using Raman spectroscopic analyses supported the spinel phase formation with high quality. Cation distribution determined from Mössbauer spectroscopy reveals the fact that Dy3+ occupies the octahedral site of the spinel lattice. Saturation magnetization (Ms) values calculated using Neel's two-sublattice model and cation distribution derived from Mossbauer's studies correlate well with the magnetization values obtained from SQUID measurements. The B-site hyperfine field decreases from 52.24 ± 0.10 to 49.26 ± 0.00 T, as evidenced by the Mössbauer spectra, with Dy substitution, which decreases the Fe-ion occupancy from the octahedral site of CFDO. Frequency-dependent dielectric constant indicates electron hopping in the grain interior, which ceases above 6.3 kHz. Dielectric measurements indicate that these CFDO compounds are useful for absorption at higher frequencies. Thus, using the combined approach based on Raman and Mössbauer spectroscopic analyses, the present work elucidates the structure, chemical bonding, and magnetic properties of Dy-substituted Fe-rich cobalt ferrite. CFDO may serve as a model system to apply to a class of Fe-rich ferromagnetic nanomaterials for electromagnetic and sensor applications.

Investigation of magneto-electric properties of La0.85Nd0.15Fe0.9Ti0.1O3

Solid state reaction route was employed to synthesize nanoparticles of undoped LaFeO3 (LFO) and Nd3+-Ti4+ co-doped LFO (La0.85Nd0.15Fe0.9Ti0.1O3, LNFTO) therein was considered to modulate its magneto-dielectric properties. The prepared samples were annealed at 1400 ℃ for 4 h to get the desired crystallographic phase. From the recorded X-ray diffractograms (XRD) it was confirmed that both dopants, Nd3+ and Ti4+ successfully entered in LFO lattice with some deviations from ideal perovskite lattice where the FeO6 octahedron is distorted. The XRD data were also used for extracting cell parameters using Rietveld analysis. Raman spectroscopic data of LFO and LNFTO were recorded at room temperature (RT) to identify the presence of impurities, if any. Magnetization (M) vs applied field (H) of LNFTO recorded at 300, 5 and 2 K show the presence of magnetic ordering with fruitful modulations in shape of curve and value of magnetization in co-doped sample compared to those of LFO. Analysis of M vs temperature (T) curve indicates that co-doped sample of LNFTO is in mixed phase of ferromagnetism and antiferromagnetism. Frequency-dependent dielectric constant (ε′), dielectric loss tangent (tanδ), ac conductivity (σ′), z parameters of LNFTO were measured at different temperatures (in the range of 25 ℃ to 225 ℃). ε′ value of LNFTO increases and tanδ decreases compared to undoped LFO. On the other hand, variation of σ′ with frequency of LNFTO decreases, and accordingly resistivity increases. Variation of polarization (P) with electric field (E) of LNFTO recorded at RT indicates that P-E loops of LNFTO are improved compared to that of LFO. Leakage current density (J) vs electric field (E) characterisation shows that leakage current reduces in LNFTO. Nature of the J-E curve depicts that the resistive behavior of sample LNFTO is not linear, which confirms the presence of charge storage phenomena in the samples.

Electrical Properties of PAN/PMMA Blends Doped with Lithium Salts

Polymer blended electrolytes of various concentrations of undoped PAN/PMMA (80/20, 75/25, 70/30, 65/35 and 60/40 wt%) and doped with lithium salts (LiCl, Li2SO4H2O, LiNO3, Li2CO3) at 20% wt have been prepared by the solution casting method using dimethylformamide as a solvent. The electrical conductivity has been carried out using an LCR meter. The results showed that the highest ionic conductivity was 2.80x10-7 (Ω.cm)-1 and 1.05x10-1 (Ω.cm)-1 at 100 kHz frequency at room temperature for undoped (60% PAN + 40% PMMA) and (80% PAN + 20% PMMA) doped with 20%wt Li2CO3 composite blends, respectively. It was found from the measurements of the A.C conductivity of undoped (PAN+PMMA) and doped with different lithium salts in the frequency range (1kHz-100kHz) that A.C conductivity follows empirical laws σa.c(ω)=Aωs, where (s) is (are) located between (0.501-2.054). The frequency-dependent dielectric constant at room temperature for various composites exhibited that because of interfacial space charge polarization, the dielectric constant has a large value. The fluctuation of dielectric loss with the addition of various kinds of lithium salts and frequency-dependent dielectric loss were shown and discussed.

Exploring dielectric spectra of polymer through molecular dynamics simulations

ABSTRACT In this work, poly(N-isopropylacrylamide) (PNIPAM) was used as a research object to explore the feasibility of molecular dynamics (MD) simulations to study the dielectric properties of polymers. A comparison of the static dielectric constants for two different calculation schemes, the applied electric field method and the dipole moment fluctuation method, has been conducted. The dielectric properties of PNIPAM aqueous solutions with different concentrations were studied as a function of temperature. The static dielectric constants derived from dipole moment fluctuation method at different temperatures can accurately describe the phase transition process. The concentration does not affect the lower critical solution temperature, but significantly affects the relaxation process of the system. According to the frequency-dependent dielectric constants, two relaxation processes are observed, namely, the dielectric relaxation process in the region of frequency less than 30 terahertz (THz) determined by the synergistic interaction of PNIPAM and water molecules, and that in the region of frequency higher than 30 THz mainly determined by water molecules beyond the solvation shell of the polymer. The calculation results suggest that the dielectric behaviour is concentration and temperature independent, similar to Debye behaviour of bulk water. This method of calculating dielectric properties using MD simulations can be used in detecting the dynamic processes of soft condensed matter and in aiding the design of materials with excellent dielectric properties.

Structural and electrical characteristics of double perovskite: Sr2FeMoO6

Sr2FeMoO6 ceramic material has been prepared by a mixed oxide reaction route. Analysis of structural, microstructural and electrical characteristics of the material has been analyzed in the limit of frequency (1 kHz–1 MHz) and temperature (25–400 °C). From the preliminary X-ray structural analysis, the structure of the material is found to be tetragonal. The frequency dependence of dielectric constant has been explained by Maxwell-Wagner effect. There is no anomaly observed in the temperature dependent dielectric analysis. The analysis of the Nyquist plot suggests the existence of only grain effect and the sample shows both characteristics of negative and positive temperature coefficient of resistance (NTCR and PTCR). The frequency and temperature dependence of ac conductivity obeys Jonschor’s power law. The analysis of temperature dependence of frequency exponent suggest that the conduction mechanism is follow the overlapping large polaron tunneling (OLPT) and correlated barrier hopping (CBH) conduction phenomena and the activation energy has also been calculated by using Arrhenius equation. The occurrence conduction phenomenon belongs to space charge limited conduction process. The observed low-leakage current density from J-E characteristics curve may be applicable for high temperature applications.

Electronic and optical responses, Compton spectroscopy and manifestation of trapping centres of LiF:Mg,Ti

Electronic structure to judge trapping centres and activation energies in Mg-doped (2–8%) and Mg,Ti co-doped (2–3% each) LiF phosphors are presented using full-potential linearized APW method. Compton measurement for LiF is performed for appropriate choice of exchange-correlation potentials used in electronic properties. It is seen that 2–6% of Mg activator leads to formation of electronic traps with activation energy between 0.79 and 0.49 eV. At high concentration (>6%) of Mg, the formation of trap centres vanishes. Co-doping of 2% Mg,Ti permits the formation of trap centres, which is in contrast to higher concentrations. Mg-3s states play key role in the building of electronic trap centres. Higher concentration of Ti and Mg activators in LiF leads to the widening of 3d and 3s states, respectively. Analysis of optical response (frequency-dependent dielectric constants, trapping centres, and absorption coefficients) of 2% Mg-doped and 2% Mg,Ti co-doped LiF suggest their dosimetric applications and in ultra-violet detection.

Structural and electrical properties of four folded layered BaBi2Sb2Ti4O15 compound

BaBi2Sb2Ti4O15, a four-fold layered structured ceramic compound is synthesized by the mixed oxide process at sintering temperature 875 °C. The structural and electrical properties of the material measured in a broad temperature (25–500 °C) and frequency (103–106 Hz) range are presented here. From the preliminary X-ray structural analysis, it is confirmed that this compound has an orthorhombic structure. The temperature and frequency-dependent dielectric constant of the material is observed. Modified Curie Weiss’s law explains the extent of diffusivity observed in a phase transition. The presence of grain and grain boundary effects is confirmed from the Nyquist plots. Non-Debye-like relaxation is noticed from complex impedance and modulus analyses. Reduction in grain resistance is noticed with the enhancement of temperature indicating the existence of negative temperature coefficient of resistance (NTCR) properties in the compound. It is concluded from the above results that this compound may have wide applications in electronics as well as high-temperature devices.