Investigation of structure, morphology, dielectric, and optoelectronic properties of La-doped BaZrO3: experimental and DFT analysis

Abstract

In this work, Ba_1-xLa_xZrO₃ (x = 0, 0.04, 0.08, 0.12, 0.16) samples were prepared using a solid-state reaction method. The analysis of XRD patterns ensured the cubic structures with space group Pm3m and lattice parameters by Rietveld refinement. The density functional theory (DFT) has been employed to study the electronic band structure and density of states. The field emission scanning electron microscope (FESEM) is used to investigate the surface morphology of studied samples and calculate the average grain size in the 0.2 to 0.8 µm range. Fourier transform infrared (FTIR) spectroscopy observes the existence of functional bonding in all samples. The dielectric and impedance measurements have been carried out using electrochemical impedance spectroscopy (EIS) in the high-frequency region. The electronic and optical of pure BaZrO₃ and Ba_1-xLa_xZrO₃ (x = 0.12) are computed by density functional theory (DFT) calculations. The BaZrO₃ has an indirect band gap of 3.52 eV, whereas Ba_1-xLa_xZrO₃ (x = 0.12) reveals a direct band gap of 3.36 eV. The band gap transitions from an indirect to a direct band gap with La-doping. The optical characteristics, such as dielectric constants, absorption coefficient, reflection, refractive index, optical conductivity, and optical loss, are investigated, and Ba_1-xLa_xZrO₃ (x = 0.12) responds optically well to the ultraviolet range. This analysis suggests that Ba_1-xLa_xZrO₃ is a suitable candidate for UV-based photovoltaics and photodetectors.