Synthesis and characterization of new pyrochlore solid solution Bi1.5Sb1.5Cu1-xMnxO7

A new pyrochlore solid solution with formula Bi1.5Sb1.5Cu1-xMnxO7 has been synthesized using ceramic method at 1000 degrees C. The cell parameter decreases linearly with increasing manganese concentration. Rietveld refinements for (B1.5Mn0.5)(Sb1.5Mn0.5)O-7 compound using X-ray powder diffraction data confirmed an overall A(2)B(2)O(7) cubic pyrochlore structure with a = 10.42749 (4)angstrom and Fd-3m symmetry. The reliability factors are R-wp = 3.48%; R-p = 2.37%; R-exp = 1.65% and R-Bragg = 1.58%. The magnetic susceptibility measurements achieved between 4 and 300 K indicate a paramagnetic behaviour with an oxidation state "2+" of the manganese ion. The electric resistance measured using complex impedance spectroscopy method put in evidence a decrease of the electric resistance with the temperature, which reached 5 x 10(2) Omega at 675 K. Dielectric properties depend on the variation of frequency and temperature, results indicate a conductive compound. (C) 2009 Elsevier B.V. All rights reserved.