The refinement of the crystal structure of synthetic syngenite K2Ca(SO4) · H2O has been carried out through the Rietveld method on X-ray powder diffraction data. Space group is P21/m, a = 9.7710(2) Å, b = 7.1449(2) Å, c = 6.2469(1) Å, β = 103.992(2)°. Conventional agreement indices are Rp = 5.26%, wRp = 7.02%, RF = 3.91%, reduced χ2 = 1.185. The structure consists of an alternation of sheets made of columns of KO8 polyhedra linked by zig-zag chains of CaO9 polyhedra and by two independent sulfate groups S1 and S2. Both Ca and K cations coordinate the water molecule and each H forms a hydrogen-bond with O4. The Ow.....O4 distance of 2.69(1) Å is in good agreement with 2.75Å derived from IR measurements.
Refinement of the structure of synthetic syngenite K2Ca(SO4)2 • H2O from X-ray powder diffraction data / Ballirano, Paolo; Belardi, G; Maras, Adriana. - In: NEUES JAHRBUCH FUR MINERALOGIE-ABHANDLUNGEN. - ISSN 0077-7757. - STAMPA. - 182:1(2005), pp. 15-21. [10.1127/0077-7757/2005/0027]
Refinement of the structure of synthetic syngenite K2Ca(SO4)2 • H2O from X-ray powder diffraction data
BALLIRANO, Paolo;MARAS, Adriana
2005
Abstract
The refinement of the crystal structure of synthetic syngenite K2Ca(SO4) · H2O has been carried out through the Rietveld method on X-ray powder diffraction data. Space group is P21/m, a = 9.7710(2) Å, b = 7.1449(2) Å, c = 6.2469(1) Å, β = 103.992(2)°. Conventional agreement indices are Rp = 5.26%, wRp = 7.02%, RF = 3.91%, reduced χ2 = 1.185. The structure consists of an alternation of sheets made of columns of KO8 polyhedra linked by zig-zag chains of CaO9 polyhedra and by two independent sulfate groups S1 and S2. Both Ca and K cations coordinate the water molecule and each H forms a hydrogen-bond with O4. The Ow.....O4 distance of 2.69(1) Å is in good agreement with 2.75Å derived from IR measurements.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
