X-RAY STRUCTURE REFINEMENT OF (3-DIMENSIONAL INCOMMENSURATE COMPOSITE(1-X)TA2O5.XWO(3), X=0.1(1))

The structure refinement of tantalum tungstate, (1-x)Ta2O5.xWO(3), x = 0.1, as a (3 + 1)-dimensional incommensurately modulated composite st ructure was carried out using X-ray single-crystal diffraction data me asured with Mo K alpha, radiation. The composite structure consists of two component substructures referred to as the metal-substructure (M) , a(M) = 6.188(1), b(M) = 3.665(1), c(M) = 3.886(1) Angstrom, and the oxygen-substructure (O), a = a,, b, = 2.251 b,/1.628, c,=c,, respectiv ely. The primary modulation wavevector of the M substructure is chosen to be q(M) = b(0) = 1.628 b(M)*. The overall superspace-group symmet ry is C'mmm(OBO)sOO. The structure was refined to an overall uR=0.0561 . The structures of the com-