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BaBiLaNbVO9 is a lead-free compound and has been synthesized by solid-state technique. The formation of the compound was confirmed by X-ray diffraction and is found to be crystallized in the monoclinic (space group P 21) crystal system (a = 13.7464± 0.0015 Å, b = 4.0156± 0.0012 Å, c = 12.4946 ± 0.0018 Å, β = 93.48 ± 0.01o). The crystallite size was found to be 52.91 nm. SEM and EDX studies analyzed the morphology, composition, and elemental distribution in the specimen. The average grain size is about 1.0651 μm. Several properties, such as frequency and temperature response resistivity, conductivity, and dielectric behaviours of the compound, have been analyzed. The overlapping large polaron tunnelling (OLPT) and correlated barrier hopping (CBH) models are appropriate for electrical conduction in the compound. The energy band gap (Eg) of the material was 2.40 eV, suitable for optoelectronic devices. Ferroelectric behaviour may be deduced from symmetric and well-shaped P-E hysteresis loops. The impedance study satisfies the negative temperature coefficient of resistance (NTCR) behaviour, which is suitable for thermistor devices and its correlated application. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Traditional sonic crystals (SCs) are based on scatterers or resonators distributed periodically that attenuate sound waves in different bands of frequencies. Recently, we adopted an improved design of SC, namely, the gradient-based sonic crystal (GBSC), designed with a gradient in the geometric parameters using nonuniform resonators and lattices. The finite element (FE) study on the GBSCs indicated that the gradient induces better attenuation than the traditional periodic SCs. This work is an extension of our previous work with experimental and new FE studies on different parameters of the GBSC in an attempt to improve the attenuation of the GBSCs. It was found that the gradient of the geometry enhances the Bragg scattering and resonance in the array, creating a large number of band frequencies. When designed properly by manipulating their gradient, GBSCs were found to target particular frequency bands over other GBSCs of identical filling ratios by coupling the resonant frequencies or the resonant and Bragg frequencies. It was also found that the thickness of the GBSC can be reduced by removing some specific columns from the array without significantly affecting the attenuation by the GBSC. Similarly, it was also found that the relative position of the resonator columns in a GBSC affects the band frequencies, and swapping the columns may also improve the attenuation by the GBSC. [ABSTRACT FROM AUTHOR]

The solid-state reaction route created the lead-free dielectric material CaBiLaNbVO9 at a high temperature. The polycrystalline compound belongs to a monoclinic crystal structure having dimensions a = 10.6738 Å, b = 10.4488 Å, c = 7.1793 Å, and V = 798.04 Å3. The grain size is calculated to be 1.1029 µm. The doping of La3+ at the Bi-site and divalent cation Ca2+ substituted at site-A and Nb5+, V5+ in the site-B of ABO3 has considerably modified the structural, dielectric, and electrical conduction mechanism. The study of ac conductivity (frequency-temperature characteristics) shows CBH (correlated barrier hopping) and NSPT (non-overlapping small polaron tunneling) conduction mechanisms. Non-Debye type relaxation has been observed using impedance analysis. The modulus and impedance study have been used to confirm the short-range order of charge carriers. The average transmittance of the compound is about 82–84%, and absorption is in the range of 0.1–1.0% in the visible area applicable for transparent conductive oxide. The energy band gap is 2.73 eV. The analysis of the resistive and capacitive properties indicates the material is an electronic component for the creation of devices. [ABSTRACT FROM AUTHOR]