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In reviewing the growth, development and properties of dielectrics, it is worth discussing the issues of creating new materials and understanding the origin of the properties shown with external stimuli. Beginning with a brief summary of the history of the dielectric materials, this review focuses on the chronological development and recent works with possible future applications. At present, the broad class of dielectrics becomes interesting from the point of view of its diverse applications in various fields. Solid dielectrics are perhaps the most commonly used dielectrics in electrical engineering, and many solids are very good insulators. As we know, solids may be classified according to various criteria: (i) structure (as crystalline and non-crystalline solids); (ii) electrical conductivity (conductors, semiconductors and insulators); (iii) the existence of some basic properties. Dielectric materials can be divided into 32 crystal classes or point groups.

This article describes the characterization (structural, topological, dielectric, and electrical properties) of a lead-free complex perovskite Ca 3 Bi 2 WO 9 (CBWO) prepared by a solid-state reaction method. The room-temperature X-ray structural analysis of the material suggests crystallization of the material in monoclinic crystal symmetry with average crystallite size and lattice strain of 73.29 nm and 0.0023, respectively. Studies of microstructural and compositional properties of the sample using scanning electron microscopy (SEM) and EDX (energy-dispersive analysis X-ray) revealed the good quality of the sample (uniformity and compactness of grains and grain boundary). A careful examination of the temperature and frequency dependence of the impedance, dielectric, and ac conductivity characteristics of the material shows the existence of large dielectric dispersion, relaxation mechanisms, and a non-Debye type of conduction mechanism in it. The diminishing of resistance or radius of semicircular arcs in Nyquist plots and impedance analysis show the semiconductor behavior of the material. Fitted parameters obtained using ZSIMPWIN software also support this nature. The nature of field-dependent polarization [hysteresis loops ( P – E )] shows that ferroelectricity may exist in the sample. The negative temperature coefficient of resistance (NTCR) character, which applies to NTC thermistor application, is shown by calculating the temperature coefficient of resistance (TCR) and thermistor constant ( β ).

Composites derived from polyvinylidene fluoride (PVDF) play an important role in advanced dielectric energy storage due to their outstanding characteristics, including remarkable flexibility, low density, high dielectric permittivity, and superior dielectric breakdown strength. The strategically designed composition significantly enhances the energy storage performance, such as discharge energy density (Ue) and charge–discharge energy efficiency (η). Consequently, we employed the solution cast method to create flexible composite films, combining PVDF polymer with strontium tungstate (SrWO4) ceramic. X-ray diffraction analysis revealed the coexistence of α and electroactive β phases in PVDF. These phases have a substantial effect on the dielectric characteristics and energy storage density of composites. Flexible nanocomposites of PVDF and SrWO4 exhibit high dielectric constant and low tangent loss. Micrographs obtained using scanning electron microscopy (SEM) showed that the morphology of the composite varies according to the amount of filler present in the matrix. The impedance spectroscopy method yielded intriguing findings regarding the roles of both grain and grain boundaries in the overall resistance characteristics of the composites. The frequency-dependent behavior of alternating conductivity follows Jonscher’s power law. The hysteresis loops indicate that the nanocomposite film maintains favorable ferroelectric properties. The present study suggests some promising applications for advanced dielectric capacitors and energy storage devices.

In this study, the aim is to determine the dielectric, electrical, and ferroelectric properties of lead-free (Bi1/2Cs1/2)(Fe1/3Mn1/3W1/3)O3 (BCsFMWO) low-density ceramic (calcined material). The calcined Cs/Mn/W modified BFO material (green pellet) was prepared by a solid-state method. The compound was analyzed to be monoclinic obtained at room temperature XRD. The crystallite size was found to be 26.15 nm. The grain size of the compound is 0.632 μm. The morphology and purity were investigated by SEM and EDX. A significant behavior in ε r and tan δ was observed in the temperature 25°–400 °C and frequency (10 kHz–1 MHz). The impedance behavior indicates the non-Debye-type relaxation. A careful examination of the temperature and frequency dependence of the impedance characteristics of the material shows the existence of relaxation mechanisms and a non-Debye type of conduction mechanism in it. The conductivity study (Jonscher’s power law) indicates the presence of a conduction mechanism. The P-E loop shows the ferroelectrics behavior. The Ohmic and Space Charge Limited Current conduction mechanism (SCLC) was found at low and high electric fields (voltage) under forward bias current–voltage situations. The negative temperature coefficient of resistance (NTCR) character, which applies to NTC thermistor application, is shown by calculating the temperature coefficient of resistance (TCR) and thermistor constant ( β ). The NTCR behavior of the compound strongly supports the material for temperature-based sensors.

Some types of ferrites have garnered notable attention lately due to their versatility in various applications. This paper reports the influence of sintering effect on dielectric and electrical characteristics of (Bi 1/2 Cs 1/2 )(Fe 1/3 Mn 1/3 W 1/3 )O 3 (BCsFMWO) compound, prepared by a solid-state reaction method. An increase in atomic kinetic mobility promotes grain development and crystallization improvement. Furthermore, the sintering temperature primarily influenced the dielectric loss and dielectric constant of the ceramic. The ceramic with high density exhibit reduced dielectric losses and fewer internal defects, essential for the optimal performance of electrical devices. The impedance response suggests a dielectric relaxation pattern that deviates from the Debye model. Meanwhile, the conductivity analysis, based on Jonscher’s power law, reveals the existence of a specific conduction mechanism. A polarization study with the hysteresis loop was done to confirm the dominance of the ferroelectric contribution over the sintered one. The value of α (temperature coefficient of resistance) is nearly − 1.2%/°C at 350 °C, which strongly supports the use of the material for temperature-based sensors. The temperature coefficient of resistance signifies its use in high-temperature sensor devices. The sintering process causes the Ohmic behavior of the sample to disappear at low voltages, as well as trap-filled SCLC conduction behavior. The probable causes of all of the foregoing observations were discussed.

In this report, we present the fabrication through the solid-state method and subsequent characterization (structural, electrical, optical, and thermal properties) of a lead-free Na/W modified complex BiMnO 3 ceramic of a chemical composition (Bi 1/2 Na 1/2 )(Mn 1/2 W 1/2 )O 3 . The structural analysis, including the determination of structure and lattice parameters, was performed using X-ray diffraction data, revealing a monoclinic crystal structure of the material. Additional insights into its vibrational properties were obtained through Raman spectroscopy and Fourier Transform Infrared spectrum. The electronic behaviour of the prepared sample was investigated using photoluminescence (PL). Scanning electron microscope analysis revealed a uniform distribution of grains. The energy-dispersive X-ray study confirmed compositional uniformity. Furthermore, a comprehensive analysis of dielectric properties, impedance, modulus, and conductivity was carried out over a range of frequencies (1 kHz – 1 MHz) and temperatures (25 °C – 500 °C) to understand the Maxwell–Wagner type of dielectric dispersion, relaxation, and transport mechanisms. The Nyquist plots and the temperature-dependent conductivity data exhibited a negative temperature coefficient of resistance behavior. The modulus data indicated a scaling nature, indicative of non-Debye type relaxation. Additionally, the study of polarization with an electric field suggested the possibility of a ferroelectric behavior of the material.

The report in the article has emphasised the characterisation (structural analysis, sample microstructure, dielectric, impedance, and modulus) of a layered perovskite ceramic oxide LiNdSnO 4 (LNSO) prepared by solid-state reaction method. The compound formation and phase identification with multiphase are confirmed using X-ray diffraction (XRD). This XRD shows that the material contains LNSO as the predominant and minor impurity phases. The crystallite size and strain are calculated to be 106 nm and 0.001, respectively. SEM study shows that the grains formed in the sample are a combination of the big (~ 2.23 μm) and small grains (~ 0.95 μm). The ac conductivity follows the Jonscher’s power law. The non-Debye type of relaxation mechanism and the hopping mechanism are shown by the shifting of the curve in the high-frequency zone in modulus spectra. The FT/IR study demonstrates the presence of a vibrational band in each element of the sample. The dielectric constant and loss increased sharply at 300 °C. The maximum activation energy (0.5598 eV) was found at a lower frequency. Nyquist spectrum indicates the presence of grain and grain boundary properties of the material. The semicircular behaviour of impedance spectra demonstrated that the material might be semiconducting. This study concluded that the compound is useful for NTCR thermistor devices.

This article thoroughly investigates the structural and electrical properties of a layered perovskite structure, KSmSnO 4 (KSSO), which was synthesized using the solid-state method at high temperatures. The compound has a cubic crystal structure (a = b = c = 10.535 Å). The surface morphology is done by scanning electron microscope (SEM), which shows the homogenous distribution of grains. The compositional analysis was carried out by EDX. The study of conductivity, modulus, dielectric constant, dielectric loss and impedance analysis was done. The electrical analysis of the compound has been done which describes the change of dielectric constant and dielectric loss concerning temperature and frequency. The complex impedance spectroscopy (CIS) is done for the frequency (100 Hz to 1 MHz) and for the temperature (25–500 °C). The calculated data and fitted data matches well in the nyquist plot. The variation of imaginary part of the modulus with frequency was fitted using KWW function. The variation of the ac conductivity of the material under alternating current varies according to Jonscher's universal power law. The activation energy was calculated for the frequency 100 Hz to 1 MHz.This article concludes by discussing future possibilities and scientific challenges in NTCR thermistor using KSSO.