Crystal structure of a new gallium tellurite: Ga_2Te_4O_(11)

摘要

Ga_2Te_4O_(11) crystallises with triclinic symmetry (space group P1) and unit cell parameters: a = 5.125(1) A, b = 6.559(1) A, c = 8.173(2) A, #alpha# = 75.06(2), #beta# = 89.25(2), #gamma# = 69.62(2), Z = 1. Its crystal structure has been refined by a full matrix least-squares process to R_1 = 0.023 and Wr_2 = 0.060 values, on the basis of 2931 independent single crystal X-ray reflections. It can be described as a three-dimensional polyhedral network of independent Te_2O_6 groups of TeO_3 trigonal pyramids and TeO_4 disphenoids sharing corners, and infinite (Te_2O_5)_(infinity) quasi-linear chains of the same corner-sharing TeO_3 and TeO_4 units, linked one to the other via common corner or common edge by GaO_4 and GaO_5 polyhedra. The stereochemical activity of the lone pair of each Te atom has been analysed and a comparison is made with all the known other M_2Te_4O_(11) crystal structures.