Synthesis, crystal structure, Mossbauer spectrum, and magnetic susceptibility of new pyrochlore compound CaNdFe1/2Nb3/2O7

A new pyrochlore compound CaNdFe1/2Nb3/2O7 was synthesized by a wet chemical method. The Rietveld method is used to determine the crystal structure of the compound. The crystal structure of CaNdFe1/2Nb3/2O7 belongs to cubic system with a cubic face-centered cell and a = 1.04138 nm, Mossbauer spectrum of the Fe-57 nucleus in the compound shows the absence of the internal magnetic field in the compound and the low spin state of the trivalent iron ion. The temperature dependence of the magnetic susceptibility indicates the paramagnetic property of CaNdFe1/2Nb3/2O7. There may be translation from the Fe-III ion in a low spin state to the Fe3+ ion in a high spin state in the compound when the temperature is higher. (C) 2000 Academic Press.