CRYSTAL-STRUCTURE OF ND2TE4O11 - AN EXAMPLE OF A RARE-EARTH TELLURIUM OXIDE

The preparation and growth of single crystals and crystal structure determination of Nd2Te4O11 are reported. It crystallizes in the monoclinic system, space groupC/2c,with parametersa = 12.635(6)Å,b = 5.204(1)Å,c = 16.277(3)Å, β = 106.02(8)°, andZ = 4.An agreement factor ofR = 2.3%was obtained after refinement of positional and anisotropic thermal parameters. The structure is described as an interconnecting network of NdO8 distorted square antiprisms, which link in two dimensions through edge sharing, with TeO4 polyhedra which link in the same two dimensions through corner sharing. Sheets of (Nd2O10)∞ join with those of (Te8O20)∞ to form a three-dimensional network. The location and role of the lone pairs are discussed. The structure can also be described as a distorted hcp array of oxygen ions, neodymium ions, and lone pairs in which tellurium ions occupy selected trigonal bipyramidal sites. © 1990 Academic Press, Inc. All rights reserved.