Influence of Ti-substituted hole-doped La1.5Sr0.5CoMnO6 double perovskite on microstructure and electrical transport properties

Abstract

In this paper, a new Ti-substituted at the Mn site of hole-doped double perovskite La_1.5Sr_0.5CoMn_1-xTi_xO₆ (x = 0.0, 0.5, and 1.0; LSCMT) prepared by solid-state reaction and the effect of Ti-substitution on its structural and electrical transport properties is presented. The structures of La_1.5Sr_0.5CoMnO₆ (LSCMO), La_1.5Sr_0.5CoMn_0.5Ti_0.5O6 (LSCMTO), and La_1.5Sr_0.5CoTiO₆ (LSCTO) ceramic oxides were analyzed using powder X-ray diffractometer (PXRD) and phases are confirmed by the Rietveld refinement method and Raman spectroscopy studies. The LSCMO and LSCMTO were refined as monoclinic symmetry (space group P2₁/n), while in the case of the LSCTO sample the best fitting was obtained for the orthorhombic symmetry (space group Pbnm). The ceramic grains are distributed in the range from 0.2 to 2.2 μm size in scanning electron micrograph(SEM).The temperature (298 to 573 K) and frequency (1 kHz to 1 MHz) dependent dielectric behavior are studied to examine the electrical properties of these ceramic materials. We analyzed the frequency and temperature-dependent electrical data using the framework of conductivity and electric modulus formalisms. The electrical and transport activities in the material are investigated by analyzing the spectra of impedance, modulus, and ac conductivity at varying frequencies and temperatures. The relaxation feature of the material is illustrated through modulus spectroscopic techniques and hopping conduction mechanism is depicted through ac conductivity spectra. The present study examines the effects of Ti-cations with relatable radius at the B/B′ site of La_1.5Sr_0.5CoMn_1-xTi_xO₆ (0 ≤ x ≤ 1.0). The same values of activation energy implies the presence of the same relaxation mechanism in materials with the same charge carriers.