Abstract
A new complex oxide with a pyrochlore-related structure Dy 2MnTa 1+ x O 7+δ was synthesized from the oxides Dy 2O 3, Ta 2O 5 and Mn 2O 3 at 1523 K in air. The X-ray diffraction patterns could be assigned to a hexagonal symmetry. The lattice parameters are a = 7.3917 ± 0.0003 A ̊ and c = 17.1473 ± 0.0009 A ̊ . It is shown by thermogravimetric analysis that the nonstoichiometric phase of Dy 2MnTa 1+ x O 1+δ exists stably over the range of oxygen partial pressure 1 ∼ 10 −21 atm at 1273 K. A magnetic measurement shows that the quaternary oxide Dy 2MnTa 1+ x O 7+δ has a paramagnetic property and the valence numbers of dysprosium and tantalum are 3 + and 5 + respectively, while that of manganese includes 2 +, 3 − and 4 + depending on the oxygen nonstoichiometry. Semiconducting property was also observed from the results of electrical conductivity in the measured temperature range.
Published Version
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