Synthesis and characterization of the new pyrochlore Bi1.5Sb1.5−xNbxMnO7 solid solution

The solid solution with formula Bi_1.5Sb_1.5−xNb_xMnO₇ has been synthesized using the ceramic method at 1000 °C. This solid solution was crystallized in the pyrohlore structure in cubic lattice with Fd-3 m space group. The cell parameter increases linearly with increase in the niobium concentration. The magnetic susceptibility measurements achieved between 4 and 300 K show a paramagnetic behaviour with an effective moment 5.84 μ_β for Bi_1.5Sb_1.5MnO₇ compound (x = 0) and 5.61 μ_B for Bi_1.5Nb_1.5MnO₇ compound (x = 1.5) indicating “ + 2” oxidation state for manganese ion. The electric conductivity measured using the complex impedance spectroscopy method put in evidence an increase of the electric conductivity with the temperature, and the antimony compound is slightly more conductor than the niobium compound; results indicate electronic conductivity with semi-conducting behaviour.