Magnetic properties of ordered perovskites Ba2LnTaO6(Ln = Y, lanthanides)

Magnetic properties of the quaternary oxides Ba 2 LnTaO 6 (Ln = Y or lanthanides) are reported. Their powder x-ray diffraction measurements and Rietveld analysis show that they have an ordered perovskite structure and are monoclinic (Ln = La-Tb) with space group P 2 1 / n or cubic (Ln = Y, Dy-Lu) with space group Fm m . Magnetic susceptibilities of Ba 2 LnTaO 6 were measured. All compounds in this work are paramagnetic down to 5 K. Ba 2 EuTaO 6 and Ba 2 SmTaO 6 show Van Vleck paramagnetism; their spin-orbit coupling constants are determined to be 331 cm -1 and 287 cm -1 , respectively. 151 Eu Mössbauer measurements for Ba 2 EuTaO 6 were carried out at 12, 100, 200 and 300 K. The Eu ion is in the trivalent state, and the symmetry of the Eu site is distorted from the octahedral symmetry. The Debye temperature of Eu 3+ was determined to be 335 K from the temperature dependence of the absorption area of intensity curves.