Preparation, electrical conductivity and magnetic susceptibility of Eu2Mn2/3Nb4/3O7

A new complex oxide Eu2Mn2/3Nb4/3O7 with a pyrochlore-related structure has been prepared from Eu2O3, MnO and Nb2O5 at 1523 K in a reducing atmosphere. The X-ray diffraction patterns of this compound can be indexed by hexagonal symmetry with the lattice parameters a = 15.102(3) Angstrom, c=17.417(6) Angstrom. Electrical conductivity shows a semiconducting property. It is shown from the results of magnetic susceptibility that this compound has a paramagnetic property in the temperature range 77-600 K and that the valence numbers of Eu, Mn and Nb in Eu2Mn2/3Nb4/3O7 are 3(+), 2(+) and 5(+), respectively.