The structural, spectroscopic and electrical behavior of rare earth doped neodymium chromites

Abstract

Perovskite lanthanum-substituted neodymium chromites (Nd${}_{1-x}$La${}_x$CrO${}_3$, $x=0,0.04,0.08$) synthesized using the solid-state route technique are described in this study in terms of their structural, optical, and electrical properties. The Rietveld refinement of X-ray diffraction (XRD) data validated the samples’ phase purity and crystal structure. To examine the diffuse reflectance spectra and elucidate the effect of lanthanum doping on their band gaps, the Tauc plot of the Kubelka–Munk function was employed. The notable optical behavior, such as indirect to direct band gap transition and band gap modification through doping, renders these materials essential for a wide range of optoelectronic applications. Neodymium chromite, pure and doped, exhibited temperature- and frequency-dependent dielectric properties in their broad dielectric spectroscopy, making them suitable for various electrochemical and electrical applications. A significant dielectric constant value, observed at room temperature, suggests the material is a ferroelectric relaxor. This study investigates the AC conductivity behavior of pure and doped materials as potential candidates for advanced electrochemical applications. Our results indicate that the temperature- and frequency-dependent conductivity significantly changes after doping, suggesting that certain applications require tailored conductivity characteristics. To optimize the performance of neodymium chromites, it is crucial to understand the activation energy, which is examined using the Arrhenius plot. The impact of dopants on the conductivity, grain–grain boundary effects, and the relaxation processes in NdCrO${}_3$ was also elucidated by analyzing the impedance spectra. Our studies on the pure and doped forms provide a comprehensive understanding of the electrical behavior of NdCrO${}_3$, which is essential for enhancing its performance in electronic and electrochemical applications.