Crystal structure of the Fe-member of usovite

Abstract

The compound with the idealized composition Ba2CaFeAl2F14 crystallizes in the usovite structure type. Two models with different treatment of the disordered Fe site are presented.

A total scattering study of prenucleation structures in saturated aqueous magnesium sulfate – observation of extended clusters

“…In its anhydrous form magnesium sulfate is hygroscopic and it is thus usually encountered in one of its many hydrated forms, MgSO 4 ÁxH 2 O (x = 0-2, 4-7, 9 & 11 have known crystal structures). [8][9][10][11][12][13][14][15][16][17] The relative stability and crystallisation pathways of these hydrates is complex, for example at atmospheric pressure the undecahydrate is unstable above 275 K and breaks down into a mixture of crystalline heptahydrate and saturated solution, 18 whereas at a pressure of 0.9 GPa and temperature of 240 K it decomposes to a mixture of ice VI and the enneahydrate. 16…”