SYNTHESIS, CRYSTAL-STRUCTURE AND INTERCALATION BEHAVIOR OF HAFNIUM PHOSPHATE DIHYDROGENPHOSPHATE DIHYDRATE

A highly crystalline compound Hf(PO4)(H2PO4). 2H(2)O (gamma-HfP) has b een prepared via the partially substituted gamma-HfP sodium phase, by the reflux method. Its crystalline structure was solved by X-ray powde r diffractometry: monoclinic, space group P2(1), a = 5.3499(3), b = 6. 5949(4), c = 12.3939(8) Angstrom, beta = 98.594(5)degrees and Z = 2. T he final agreement factors are: R-wp = 0.054, R-exp = 0.031 and R-F = 0.033. The compound is isostructural with gamma-ZrP and has a layered structure built from PO4 tetrahedra and HfO6 octahedra stacked along t he [001] direction. Its intercalation behaviour with n-alkylamines (n = 1-6) and cyclic amines (aniline, benzylamine, cyclohexylamine, piper idine and pyridine) was studied. The intercalation solids obtained pre sent expanded interlayer distances and a general composition Hf(PO4)(H 2PO4). xamine . H2O where x varies from 0.8 to 2.