Exploring structural, optical, dielectric and electrical attributes of a La based complex perovskite

Abstract

A rare-earth based novel compound with a disordered perovskite structure has been synthesised using the conventional solid-state reaction approach. The structural phase of the compound is analysed using room temperature X-ray diffraction (XRD) data. The refinement of XRD data suggested formation of compound in trigonal phase with R-3c symmetry. Position of peaks in Raman spectra obtained at room temperature further support the proposition of above structure and symmetry of formation. Using scanning electron microscope (SEM) images, the microstructure of the compound and the surface morphology is revealed. EDX analysis presented semi-quantitative information on distribution and weight percentage of elements present, from which the synthesis of the expected compound is substantiated. Examination of optical characteristics via UV–Visible absorption spectroscopy revealed a band gap of 3.2 eV suggesting possible potential applications in optoelectronic and photovoltaic devices. The electric polarisation and relaxation phenomena prevailing in the material as a function of frequency and temperature are extensively studied using data acquired via complex impedance spectroscopy (CIS) technique. A temperature and frequency stable dielectric response in high frequency region recommends use of compound for application at high frequency and temperature. Dominating bulk contribution to overall electrical response and negative temperature coefficient of resistance (NTCR) behaviour is observed. The frequency-dependent ac conductivity data adheres to Jonscher's power law. To estimate the activation energy, which facilitates the identification of the specific charges involved in the ac conduction process, the temperature-dependant ac conductivity data is utilised.