Structural, electrical, magnetic, and optical characterization of sol–gel derived Pb0.5Ba0.5Cr2O5 pseudobrookite

Abstract

A highly crystallized pseudobrookite-type oxide named Pb_0.5Ba_0.5Cr₂O₅ was successfully synthesized via the sol–gel method. Structural and microstructural characterizations were carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results confirm that the Pb_0.5Ba_0.5Cr₂O₅ compound is an orthorhombic crystal structure, belonging to the Cmcm space group (No. 63). SEM analysis shows that the particles exhibit a relatively uniform grain distribution with narrow size dispersion with an average size of approximately 0.21 µm. Furthermore, the study of electrical properties shows that Pb_0.5Ba_0.5Cr₂O₅ is semiconducting in nature, with the variation in magnetoresistance (MR) as a function of temperature suggesting carrier diffusion effects or anomalous magnetic response at low temperatures. Magnetic study confirms that this compound undergoes an antiferromagnetic (AFM)-paramagnetic (PM) transition at a Neel transition temperature of approximately 88 K. The absorption spectra analysis confirms the presence of a direct optical band gap in the range of 5.33 to 5.7 eV, indicating the direct-band-gap semiconductor behavior of the material. Based on UV–Vis measurements, important optical parameters such as the Urbach energy and the optical extinction coefficient were determined. These optical characteristics reflect the material’s potential for optoelectronic applications. Additionally, the refractive index was derived from the reflectance data. It was found to follow Cauchy’s dispersion relation in the spectral region where absorption is significant. Furthermore, the dispersion parameters E_o (oscillator energy) and E_d (dispersion energy) were evaluated to further characterize the optical behavior of the material.