Investigation of the alkaline earth phosphates: Synthesis and crystal structure of a new strontium hydrogen phosphate form

The hydrothermal synthesis, initial characterization (EDX analysis, IR, X-ray powder pattern), and X-ray single-crystal structure are reported for a new form of strontium hydrogen phosphate (gamma-SrHPO4), The cell is orthorhombic, space group Pbca (No, 61) with a = 8.131(3) Angstrom, b = 9.258(5) Angstrom, c = 18.084(7) Angstrom, V = 1361.31(2) Angstrom(3), and Z = 16, The structure was determined from 1272 observed reflections to a final R value of 0,039. The atomic arrangement consists of two kinds of anionic layers (P(1) and P(2)) lying parallel to (001), formed by closed dimers and infinite chains of H-bonded HPO42- groups, respectively. These sheets are linked to each other via Sr2+ cations, Comparison to the crystal structure of CaBa(HPO4), is also given, the two compounds exhibiting the same arrangement. (C) 2000 Academic Press.