Structure cristalline du polyphosphate CdSr(PO₃)₄

¹ Laboratoire de Chimie du Solide Appliquée, Département de Chimie, Faculté des Sciences, avenue Ibn Batouta, Rabat, Maroc ;
² Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, USA.

Résumé

Des monocristaux du polyphosphate CdSr(PO₃)₄, isotype de CdBa(PO₃)₄, ont été obtenus par flux Les paramètres de la maille monoclinique (P2₁ /n) sont :

a = 14.823(5) Å, b = 9.046(2) Å, c = 7.088(2) Å et β = 91.07°(2). Le facteur de reliabilité final est de 0.037 (Rw = 0.049). La structure est formée de chaîne (PO₃)_∞ dont la cohésion est maintenue par des ions métalliques.

Abstract

Crystals of the polyphosphate CdSr(PO₃)₄, isostructural with CdBa(PO₃)₄, have been obtained with flux method. The parameter values of the monoclinic cell (P2₁/n) are : a = 14.823(5) Å, b = 9.046(2) Å, c = 7.088(2) Å et β = 91.07° (2). 1074 observed reflexions have been used to resolve the crystal structure. The final agreement factors are R = 0.037 and Rw = 0.049. The lattice contains infinit and meandering (PO₃)_∞ chains along the c direction with a period of four PO₄ tetrahedra. These chains are holded together with CdO₆ and SrO₈ so as to build a three dimensionnal framework. P-O distance values are varying from 1.467(8) to 1.603(7) A Cadmium atoms are located in octahedral polyhedra of oxygen ions ; Cd-O distances are ranging between 2.269(7) and 2340(7) Å Sr²⁺ ions have eight neighbouring oxygen atoms with Sr-O mean bond value 2.653(8) Å.