Structural, electrical and optical investigation of half doped YTi0.5Mn0.5O3 perovskite compounds for optoelectronic devices

Abstract

The YTi_0.5Mn_0.5O₃ (YTMO) perovskite was synthesized by the conventional solid-state method. The structural, electrical, dielectric and optical properties were investigated. The X-ray diffraction analysis and Rietveld refinements indicates that sample under study crystallizes in the orthorhombic structure with the Pmmm space group. The impedance spectroscopy studies show a relaxation phenomenon with non-Debye nature. The Nyquist plot confirms the presence of semicircles which, in turn, indicate the existence of both grain and grain boundary effect in the prepared ceramic. The study of AC conductivity has been discussed in detail and designated on the basis of the NSPT conduction mechanism. Activation energy was determined from DC conductivity as well as modulus spectra. The very equal values of the activation energies suggest that the process of the conduction mechanism and the relaxation behavior are similar. The behavior of dielectric constants was interpreted based on the Maxwell–Wagner’s theory of interfacial polarization. Thermodynamic parameters such as enthalpy, entropy have been calculated. From UV–Vis absorption spectrometry, the reflectance spectrum and the Kubelka-Munk model, reveal a direct and wide optical band gap evaluated at 4.69 eV. Moreover, the obtained Urbach energy (0.240 eV) confirms the presence of localized states in the YTMO structure. The extinction coefficient (k) was used to estimate the evolution of the refractive index n with the wavelength. Additionally, the refractive index (n) obeys to Cauchy relation. Furthermore, the dispersion coefficients were analyzed in the bases of Wemple and Di-Domenico model. The optical constants such as the skin depth and the optical conductivity were calculated and the results are discussed.