A Ba-rich celestine (SrOX7BaO13S04) filling cavities of volcanoclastic rocks from Montecchio Maggiore(Vicenza, lIaly) was studied. The role of the Ba content in the mineral was determined using X-ray powderdata, single crystal X-ray refinement, thermal and chemical a!1alyses. The unit cell parameters (obtained bysingle crystal diffraction) are a =8.408, b =5.372, c =6.897 A, and the refinement in the space group Pnma(Z =4) gives the final R value of 0.039. The average (Sr,Ba)-oxygen bond length is 2.842 A and agrees withan occupancy of Sr 87% and Ba 13%. Individual bond lengths (Sr,Ba)-O and bond strength calculationsconfirm that all twelve interactions are significant and define an irregular array around the cation.
Ba-rich celestite: new data and crystal structure refinement / Brigatti, Maria Franca; Galli, Ermanno; L., Medici. - In: PLINIUS. - ISSN 1120-317X. - STAMPA. - 14:(1995), pp. 79-80. (Intervento presentato al convegno - tenutosi a - nel -).
Ba-rich celestite: new data and crystal structure refinement
BRIGATTI, Maria Franca;GALLI, Ermanno;
1995
Abstract
A Ba-rich celestine (SrOX7BaO13S04) filling cavities of volcanoclastic rocks from Montecchio Maggiore(Vicenza, lIaly) was studied. The role of the Ba content in the mineral was determined using X-ray powderdata, single crystal X-ray refinement, thermal and chemical a!1alyses. The unit cell parameters (obtained bysingle crystal diffraction) are a =8.408, b =5.372, c =6.897 A, and the refinement in the space group Pnma(Z =4) gives the final R value of 0.039. The average (Sr,Ba)-oxygen bond length is 2.842 A and agrees withan occupancy of Sr 87% and Ba 13%. Individual bond lengths (Sr,Ba)-O and bond strength calculationsconfirm that all twelve interactions are significant and define an irregular array around the cation.
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