Double perovskites of the type LaBaNi1−xCoxTaO6 (0 ≤ x ≤ 1) have been synthesized by solid state method. The compounds crystallize in the tetragonal space group, I4/m. Rietveld refinement has been carried out to determine the phase purity and to study the cation ordering. X-ray photoelectron spectroscopy confirms Co(II) in all compositions. The end members in LaBaNi1−xCoxTaO6 show high dielectric constant values. Antiferromagnetic ordering has been observed for all the compositions and the ordering temperature in LaBaNi1−xCoxTaO6 gradually decreases with increase in Co doping, which has been attributed to the decrease in covalence of Co/Ni−O bonds.
Keywords: Perovskites; Rietveld refinement; Dielectric properties