PREPARATION AND CHARACTERIZATION OF A SERIES OF RARE-EARTH CYCLOHEXAPHOSPHATES, LN(2)P(6)O(18)CENTER-DOT-10H(2)O

Six new cyclohexaphosphates with the general formula Ln, P6O18 . 10H(2)O with Ln = La, Ce, Pr, Sm, Er, and Yb are reported. They belong to two different structure types. The first type, common to three compounds, corresponds to Ln = La, Ce, and Pr, with an orthorhombic unit cell, Z = 2, and space group P2(1)2(1)2. The second type, common to three compounds also, corresponds to Ln = Sm, Er, and Yb, with a monoclinic unit cell, Z = 4, and space group P2(1)/a. Synthesis and characterization by X-ray diffraction, IR absorption, and TA are given. (C) 1995 Academic Press, Inc.