Preparation And Study On La Doped Ca₂FeMoO₆ Double Perovskite

There has been a great deal of interest and studies in double perovskite A₂B′B″O₆(A=divalent cations;B′=transition metals;B″=non-magnetic cation,such as Mo,W,Re etc.),due to their high Curie temperature,and the low field magnetoresistance at room temperature,and their potential applications.In recent years,the researches mainly focus two aspects:(1)properties of double perovskite with different cations at A or B sites;(2)doping effects in A or B sites. When one trivalent cation substitute the divalent cation at A site,there will be a redundant electron at B site.Where the electron occupied affects the exchange interaction between the cations of B′and B″and the hyperfine parameters of B′, thus it affects the properties of the material.Therefore,it is essential to research the cation of A site replaced by other metallic ions in double perovskite materials.In this paper,we research the effect of La ions replacing Ca ions on properties of double perovskite material.A few main results are listed as follows:1.The sol-gel method was used to prepare pure double perovskite Ca₂FeMoO₆ samples under different reaction conditions and to prepare Ca_2-xLa_xFeMoO₆(x=0～0.8).The x-ray refinements shows that the crystal structure of samples still maintain the monocline with the space group of P2₁/n. But the cell parameters and the anti-site defect is increasing with x.2.The magnetic properties measurement indicates that Ms decreases with the increasing of x due to the increasing of anti-site defect and the magnetic moments of Mo.