Study of structural, morphological, optical, and dielectric behaviour of zinc-doped nanocrystalline lanthanum chromite

Abstract

The zinc (Zn)-doped-lanthanum chromite [LaCr1−xZnxO3 (0 ≤ x ≤ 0.3)] samples have been synthesised through sol–gel auto-combustion process. The influence of Zn doping on micro and morphological structure as well as on optical and dielectric properties of LaCrO3 has been analysed. Micro-structural studies have been performed using X-ray diffraction and Fourier transform infrared spectroscopy. These studies confirm the formation of single-phase samples. Rietveld refinement employing FULLPROF software is used to obtain lattice parameters, unit cell volume, density, bond lengths, and bond angles. Crystallite size is calculated using Scherrer equation. In addition, Williamson–Hall analysis is used to calculate the crystallite size and lattice strain. Crystallite size and unit cell volume are found to increase with increase in Zn content. Surface morphology is examined using the SEM–EDX analysis, which ratifies the formation of regular and homogeneous samples. The optical energy bandgap, Eg, decreases, while Urbach energy increases with the increase in Zn doping. Dielectric constant (ɛʹ) decreases with the increase in frequency, but increases with increase in the Zn doping. All the samples follow universal dielectric response model in the low-frequency range. The increase in ac conductivity with the increase in frequency indicates that the conduction mechanism is governed through small polaron hopping between localized states.