Abstract
In this work, a series of Sr-substituted lanthanum orthoferrite perovskites, La1-xSrxFeO3 (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0), were prepared using the sucrose-assisted auto-combustion route to study the effect of Sr-substitution on the structural, magnetic, and electrical properties and to investigate the impact of the entire method on different properties. The auto-combustion process and the perovskites formation were followed using differential thermal analysis-thermogravimetry techniques. The obtained different phases were characterized using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy HRTEM measurements. XRD revealed peaks attributed to SrCO3 secondary phase increases in their intensity by increasing Sr-content till predominate at x = 1.0. It also showed a transfer from orthorhombic symmetry to rhombohedral one by increasing Sr-content. The obvious contraction in the unit cell parameters by Sr-substitution could be attributed to the Fe3+ -> Fe4+ oxidation occurred to balance the total charge on molecule. The obvious increase in the magnetization by increasing Sr could be attributed to the formation of Fe4+ ions, strengthening the ferromagnetic component through sharing in the double-exchange interaction, Fe4+-O-Fe3+, as well as the formation of oxygen vacancies that disturb the uncompensated surface spin. Ac-conductivity measurements indicated a change in the entire conduction mechanism from electronic to ionic with improving conductivity by increasing Sr-content. Generally, the utilized sucrose method indicated an improvement in the obtained magnetization accompanied by lowering conductivity than previously reported systems in literature.