Structural, dielectric and electrical characteristics of lead-free compound, SrBiLaNbVO9, for NTCR application

The presence of ferroelectric material structured in a bismuth layer was essential in fulfilling the criteria for practical device applications. The SrBiLaNbVO9 ceramic was synthesized using the solid-state reaction method. The X-ray diffraction revealed the establishment of monoclinic structure. The scanning electron microscopy analysis of the sample microstructure indicates a polycrystalline nature with shape anisotropy. The electrical behavior of the sample was investigated through complex impedance analysis, revealing a negative and positive temperature coefficient of resistance (NTCR & PTCR) characteristic of a semiconductor. The nature of ac conductivity as a function of frequency is also discussed. The value of activation energy (224.38 meV to 98.859) decreases with increasing frequency, suggesting the activation of oxygen vacancy in the sample. Dielectric parameter conducted across a wide range of frequency (1 kHz-1 MHz) and temperature (25-500 degrees C) offers valuable data for potential applications. An examination of Nyquist plots suggests the presence of a non-Debye type of dielectric relaxation mechanism. The charge carriers of the compound exhibit both long and short-range ordering, as confirmed by modulus and impedance study of the compound. The overlapping large polaron tunneling (OLPT) model has explained the mechanism of temperature and frequency-dependent conductivity data. Ferroelectric behavior may be deduced from symmetric and well-shaped P-E hysteresis loops. The UV-visible spectrum shows a band gap energy of 2.74 eV, which suggests that the material can be used in optoelectronic devices. With a low loss of around 0.015 and a high dielectric value of approximately 320 at room temperature, the compound is suitable for high-frequency devices.