Synthesis and Magnetoresistance Effect of Sr₂FeMoO₆ by the Molybdic Acid Gelation

Abstract

Double perovskite Sr₂FeMoO₆ was prepared by using gelation of (NH₄)₆Mo₇O₂₄⋅4H₂O from aqueous solution in presence of Sr²⁺ and Fe³⁺ nitrates, The dried gel was pulverised and fired at 700°C for 6 hrs. It was fired again in H₂/Ar=3% flow for 3 hrs in temperature range of 850-1000°C. The products were slightly contaminated with impurities of α-Fe and FeMoO₄. They were annealed at 1000-1200°C in sealed tube. Inner part of the annealed sample at 1100°C showed magnetoresitance effect of 8.3% at room temperature with a comparable amount of impurity. Ordering of Fe³⁺ and Mo⁵⁺ was also enhanced.