STRUCTURES AND PHASE-TRANSITION OF BI2CDO2[GEO4]

The structure of Bi2CdO2[GeO4] was solved ab initio on the basis of la boratory and synchrotron X-ray powder data, The high temperature ortho rhombic phase, stable at room temperature, crystallizes in Pbcn (60), Z = 8, a = 10.4969(1) Angstrom, b = 10.0944(1) Angstrom, c = 5.60601(3 ) Angstrom, and V = 594.01(1) Angstrom(3) with 14 refinable positional parameters, The structure consists of [GeO4] tetrahedra, strongly dis torted trigonal [CdO6] prisms and irregular [BiO4+2] polyhedra, At low temperatures, the material undergoes a small distortion to monoclinic symmetry (gamma = 90.37 degrees at 20 K). (C) 1996 Academic Press, In c.