Electrical and optical analysis of Pr0.5−xGdxSr0.5MnO3 (x = 0, 0.05, and 0.1) manganite compounds prepared via solid-state process

In this work, we present a detailed investigation of the electrical and optical properties of Pr 0.5− x Gd x Sr 0.5 MnO 3 (0 ≤ x ≤ 0.1) polycrystalline compounds synthesized via a solid-state route. Impedance spectroscopy measurements were performed in the frequency and temperature ranges of 40 Hz–10 MHz and from 80 to 320 K, respectively. DC conductance (G DC ) results evince the semiconductor behavior of all studied compounds in the whole temperature range of study. Doping with gadolinium causes a lowering in G DC values and an increase in the activation energies. G DC is shown to be governed by the small polaron hopping model (SPH) at high temperatures and by the variable range hopping (VRH) model at lower ones. The AC measurements show a metallic behavior which can be described by the simplified Drude model. The optical properties were characterized using UV–Vis absorption spectroscopy. By analyzing the UV absorption measurements and based on the Tauc model, we have determined the optical bandgap of each compound evaluated at around 4.5 eV which is a high value compared with those obtained in the literature. The Urbach energy, the optical extinction coefficient, and the refractive index were calculated on the basis of absorbance measurements. In addition, the skin depth, optical conductivity, and the dispersion energy parameters as a function of the wavelength of the incident photon were determined and discussed. These compounds may be interesting in optoelectronic applications.