High-Temperature Dielectric Relaxation and Electric Conduction Mechanisms in a LaCoO₃-Modified Na_0.5Bi_0.5TiO₃ System

Abstract

This research study examines the high-temperature dielectric relaxation and electric conduction mechanisms in (x)­LaCoO3-(1 – x)­Na0.5Bi0.5TiO3 samples, where x is 0.05, 0.10, and 0.15. The findings demonstrate that all the samples exhibit two dielectric transitions: first, a frequency-dispersive shoulder at a lower temperature (T s) around 425–450 K, which is associated with polar nanoregions (PNRs), and second, from ferroelectric to paraelectric transition at the Curie temperature (T c) approximately between 580 and 650 K. The impedance analysis reveals the negative temperature coefficient of resistance behavior of the specimens. The broad and asymmetric relaxation peaks obtained from modulus spectroscopy demonstrate a wide range of relaxations, suggesting non-Debye-type behavior. Furthermore, the conductivity studies provide insights into understanding the transport phenomena in the samples. The oxygen vacancies resulting from the addition of LaCoO3 into the Na0.5Bi0.5TiO3 ceramics are responsible for the relaxation and conduction processes, and the charge carrier is doubly ionized oxygen ion vacancies. All samples except for LCNBT10 at 1 kHz exhibit a negative magnetodielectric response.

Unveiling a robust and high-temperature-stable two-dimensional ZnAl layered double hydroxide nanosheet based flexible triboelectric nanogenerator

“…Thus, the higher interfacial polarization and dipole interactions were caused by the existence of charge carriers at the interface of the PVA and ZnAl LDH nanosheets, leading to a high dielectric constant. [54][55][56][57][58][59][60] To further analyze the effect of the ZnAl LDH filler in the PVA matrix, the dielectric constant of the as-grown ZnAl LDH was also measured and is shown in the Fig. S5 of ESI.…”

“…As the frequency increased, electric dipoles could not cope with the rapid variation in the frequency, and the dielectric constant decreased with frequency. [59][60][61] In addition, the dissipation factor (tan σ) of the LDH-nanosheet-reinforced PVA nanocomposite films was calculated using the equation: tan δ ¼ ε″=ε′ where ε′ and ε″ are the real and imaginary parts of the dielectric constant. The variation in the dielectric loss of the pristine PVA and LDH-nanosheet-reinforced PVA nanocomposite films with different LDH filler concentrations is shown in Fig.…”

“…However, it is worth pointing out that the dielectric loss is still on the lower side to design a high-performance nanogenerator with low heat dissipiation. [59][60][61][62][63][64] The dielectric analysis suggests that the nanocomposite film with 5 wt% would be preferable for energy harvesting due to its high dielectric constant and comparatively low dielectric loss compared to other LDH filler loadings. The above results confirmed that the output voltage of the nanogenerator increases with increasing dielectric constant of the ZnAl-LDH-nanosheet-reinforced PVA nanocomposites.…”

Study of Dielectric Relaxation Dynamics and Transport Properties of Nd3+-Substituted Bismuth Ferrite Ceramics for Energy Storage Applications

“…The tangent loss normally exhibits similar trend as the dielectric constant (ε′) and demonstrate dispersion at low frequencies. When an AC electric field is applied, the tan δ values decrease and exhibit frequency-independent behavior at higher frequencies. , This tendency can be elucidated by the observation that in the low-frequency range, where weakly conducting grain boundaries exert a more pronounced influence, there is a greater demand for energy for electron hopping between Fe 2+ and Fe 3+ oxidation states, leading to higher losses. The high-frequency range, on the other hand, corresponds to the highly conducting grain, and electron interaction between Fe 2+ and Fe 3+ results in negligible energy dissipation.…”

Structural, Mechanical and Electrical Properties of Nelumbo Nucifera Fibers

“…This could be due to alterations in the molecular or structural dynamics of the material as temperature increases. The absence of a clear semicircle may be due to the presence of multiple relaxation processes, phase transitions, presence of impurities and broad distribution of relaxation times (Singh et al 2023). AC conductivity is an important parameter to understand the ionic transport properties of materials.…”