“Synthesis and crystal structure refinement by the rietveld method of antymony-bearing titanita”

COLOMBO, F.; PANNUNZIO MINER, E. V.

Powder Diffraction

American Institute of Physics

Año: 2009

0885-7156

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-centering of 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 atoms per formula unit can exist, and that the substitution scheme is 2 Ti4+ ↔ Al3+ + Sb5+.