Synthesis and crystal structure of the synthetic analogue of mineral minyulite K[Al2F(H2O)(4)(PO4)(2)]. Structural correlations with AlPO4-CJ2

The validation of our program of simulation for the prediction of unknown d ehydrated structures needs accurate information of the mother hydrated stru cture at the starting point. This paper describes the synthesis (95 degrees C, 10 days, autogenous pressure) and the structure (space group Pba2; a = 9 .3477 (2), b = 9.7571 (1), c = 5.5280 (1) Angstrom, V = 503.91 Angstrom (3) , Z = 2) of the synthetic homologue of two-dimensional mineral minyulite K[ Al2F(H2O)(4)(PO4)(2)]. The Al-27, F-19 and P-31 solid state NMR characteris tics are reported, as well as the thermal decomposition which confirms the prediction of a collapse of the structure. Finally, structural correlations between minyulite and AlPO4-CJ2 are given. (C) 2001 Editions scientifiques et medicales Elsevier SAS. All rights reserved.