Synthesis and crystal structure refinement by th Rietveld method of an antimony-bearing titanite Ca(Ti0.6Al0.2Sb0.2)OSiO4

COLOMBO, FERNANDO; PANNUNZIO MINER, ELISA VICTORIA

POWDER DIFFRACTION

J C P D S-INT CENTRE DIFFRACTION DATA

Año: 2009 vol. 24 p. 221 - 227

0885-7156

<!-- /* Font Definitions */ @font-face {font-family:PMingLiU; panose-1:2 1 6 1 0 1 1 1 1 1; mso-font-alt:"Arial Unicode MS"; mso-font-charset:136; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:1 134742016 16 0 1048576 0;} @font-face {font-family:Calibri; mso-font-alt:"Century Gothic"; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} @font-face {font-family:"@PMingLiU"; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:136; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:1 134742016 16 0 1048576 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin-top:0cm; margin-right:0cm; margin-bottom:10.0pt; margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri; mso-fareast-font-family:PMingLiU; mso-bidi-font-family:"Times New Roman"; mso-ansi-language:ES-AR; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> A synthetic analogue, Ca(Ti0.6Al0.2Sb0.2)OSiO4, of antimony-bearing titanite of a composition similar to that found at St. Marcel-Praborna (Italy) was synthesized using ceramic methods and the crystal structure was refined using the Rietveld method. Unit-cell dimensions (in Å) are a = 7.0184(1), b = 8.797(2), c = 6.5586(1), b = 113.700(1)º. The substitution of 40% Ti by (Al+Sb) in octahedra causes a loss of long-range coherency of the off-centered Ti atoms. The space group of Sb-bearing titanite is A2/a, like other cases of M3+-M5+-doped titanites. This study confirms that titanite with up to 0.2 Sb atom per formula unit can exist, and that the substitution scheme is 2 Ti4+ ↔ Al3+ + Sb5+.