Solid solutions between ettringite, Ca6Al2(SO4)(3)(OH)(12)center dot 26H(2)O, and thaumasite, Ca3SiSO4CO3(OH)(6)center dot 12H(2)O

A series of solid solution phases between ettringite, Ca6Al2(SO4)(3)(OH)(12 ). 26H(2)O, and thaumasite, Ca3SiSO4CO3(OH)(6). 12H(2)O, have been prepared and analysed by X-ray powder diffraction and full pattern fitting. Solid s olutions were shown to exist with both the ettringite structure (space grou p P31c) and the thaumasite structure (space group P6(3), c-axis halved). A possible discontinuity was identified, characterised by a gap in the a-dime nsion of the solid solution phases produced. This discontinuity is believed to correspond to a switch between the ettringite space group and the thaum asite space group. It is suggested that any discontinuity in the solid solu tion is caused by differences in the hydrogen bonding of the two structures . (C) 2000 Kluwer Academic Publishers.