Preparation and Characterization of Ordered Perovskite (CaLa) (MgMo) O6

摘要

The polycrystalline powder of (CaLa) (MgMo)O6 has been prepared at 1350∩ in H2/H2O and N2 flowing atmosphere. The powder X-ray diffraction pattern indicates that (CaLa) (MgMo)O6 has a monoclinic perovskite structure with the lattice constants a0 = b0 = 7.901(1) ∈, c = 7.875(1) ∈ and ャ = 89∑16`(1`), which can be reduced to orthorhombic unit cell, a = 5.551(1) ∈, b = 5.622(1) ∈ and c = 7.875(1) ∈. The infrared spectrum shows two strong absorption bands with their maxima at 590(ロ3) and 380(ロ4) cm, which are attributed to 2T1u modes indicating the existence of highly charged molybdenum octahedron MoO6 in the crystal lattice. According to the magnetic susceptibility measurement, the compound follows the Curie-Weiss law below room temperature with the effective magnetic moment 1.83(1)レB, which is well consistent with that of spin only value (1.73 レB) for Mo5+ with 4d1-electronic configuration within the limit of experimental error. From the thermogravimetric analysis, it has been confirmed that (CaLa) (MgMo)O6 decomposes gradually into CaMoO4, MoO3, MgO, La2O3 and unidentified phases due to the oxidation of Mo5+ to MO6+.