Phase Separation in the Double Perovskite Sr₂FeNbO_6-

The ceramic perovskite Sr2FeNbO6-delta was synthesized via the solution combustion precursor method. X-ray phase analysis showed that the sample is single-phase and does not contain impurities. The specific heat capacity and the Mossbauer spectra were measured for the Sr2FeNbO6-delta ceramic in the temperature range of 4-300 K. The observation of an asymmetric doublet in the Mossbauer spectra and the literature data on the magnetic susceptibility indicated the presence of two magnetic subsystems in Sr2FeNbO6-delta with antiferromagnetic exchange interactions. Based on the analysis of the temperature dependence of the specific heat capacity, we determined the Debye and Einstein temperatures.