Synthesis and Characterization of Pyrochlore Oxides Bi2MM’O7 (M : Yb, Nd, Sm; M’ : Sb, Nb, Ta)

Suwardiyanto Suwardiyanto (1) Departemen Kimia, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung 2) present address Jurusan Kimia Universitas Jember, Jember, Jawa Timur)
Djulia Onggo (Departemen Kimia, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung)
Ismunandar Ismunandar (Departemen Kimia, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung)

Indonesian Journal of Physics (IJP)
Vol 16 No 2 (2005): Vol. 16 No. 2, April 2005

Oxide compounds Bi2MM’O7 (M : Yb, Nd, Sm; M’ : Sb, Nb, Ta) have been synthesized by using solid state reaction. As a tool for predicting their stability, a stability field diagram for pyrochlore has been made. All the prepared oxides have a yellow color, except for M = Nd which is grey. Crystal structure types have been determined using powder X-ray diffraction. Single phase pyrochlore was obtained for Bi2SmSbO7, while for Bi2NdSbO7 a distorted pyrochlore was obtained. Ideal pyrochlores with small amount of Bi1.5Yb0.5O3 were obtained in Bi2YbSbO7. For Bi2MNbO7, (M : Yb, Nd, Sm) series the obtained phases were a mixture of ideal pyrochlore and small impurities of β-Nb2O5. For Bi2MTaO7 (M : Yb, Nd, Sm) series in addition to ideal pyrochlore as major phase, a small amount of MTaO4 (M : Yb, Nd, Sm) rutile phase were obtained. These observations were explained using the constructed structure map and the lattice energy arguments.