Structural and transport properties of A2HoTaO6 [A=Ba, Sr, and Ca]

Double perovskiLe oxides A(2)HoTaO(6) [A=Ba, Sr, and Ca] are synthesized by a solid state reaction technique. The RieLveld refinement of the X-ray diffraction pattern shows that Ba2HoTa013 crystalizes in cubic Fm3rn symmetry whereas Sr2HoTaO3 and Ca2HoTaO6 adopt the monoclinic P2(1)/n symmetry. The field cooled and zero held cooled magnetic susceptibilities of the materials are measured in the temperature range from 5 K to 300 K. The temperature dependence of inverse magnetic susceptibility shows the antiferromagnetic behavior of these systems. The dielectric relaxation of the samples is investigated by the Cole-Cole model in the frequency range from 50 Hz to 1 MHz and in the temperature range from 303 K to 673 K. The frequency dependent conductivity spectra follow the power law. The scaling behavior of the imaginary part of the impedance spectra suggests that the relaxation shows the same mechanism at various temperatures. (C) 2014 Elsevier B.V. All rights reserved