Showing papers by "A. Le Bail published in 1995"
TL;DR: In this paper, a microstrained crystalline model derived from the α-carnegieite structure was used to refine amorphous structures like crystalline ones, and the agreement R χ factors were the best ever obtained with a small-size model built exclusively from [SiO 4 ] tetrahedra linked by corners.
Abstract: To refine amorphous structures like crystalline ones is impossible. This statement needs now some reconsideration in the case of silica glass. Starting with a microstrained crystalline model deriving from the α-carnegieite structure, atomic coordinates refinements by the Rietveld method prove to be possible. The credibility of the study is supported by the simultaneous fit of neutron and X-ray diffraction data. The agreement R χ factors are the best ever obtained with a small-size model built exclusively from [SiO 4 ] tetrahedra linked by corners. However it is concluded that ‘best’ remains insufficient.
127 citations
Journal Article•
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12 citations
TL;DR: The structure of [Pd(NH3)4]Cr2O7 has been determined ab initio from conventional X-Ray powder diffraction data by the Patterson method as mentioned in this paper.
Abstract: The structure of [Pd(NH3)4]Cr2O7 has been determined ab initio from conventional X-Ray powder diffraction data by the Patterson method. The cell is monoclinic (space group P21/c, Z = 4), with a = 7.771(3) A, b=11.578(1) A, c=11.852(4) A, and β= 105.50(4)°. Refinements of 57 parameters by the Rietveld method, using 852 reflections lead to RB = 0.032, RP = 0.075, and Rwp = 0.092. The structure is built up from PdN4 square planes linked to Cr2O7 groups by hydrogen bonds. Hydrogen atoms could not be located.
7 citations