The first structure of a cerium(IV) phosphate: ab initio Rietveld analysis of CeIV(PO4)(HPO4)(0.5)(H2O)0.5.
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Journal Article↗
Biomedical subjects
Michel Quarton
Publications and source records attributed to Michel Quarton.
beta-Tl2SO4.
The ambient-temperature form of dithallium sulfate, beta-Tl(2)SO(4), is similar to beta-K(2)SO(4) and is characterized by isolated sulfate tetrahedra and two different thallium sites with coordination numbers 9 and 11. All the atoms, except one O atom, lie on mirror planes. In spite of there being a high concentration of Tl(+) cations, the stereochemical activity of the 6s(2) pairs is low, similar to that of isotypic Tl(2)XO(4) compounds (X = Cr and Se). This behaviour is the consequence of both weak Tl-O bonds and strong X-O bonds, because in a Tl-O-X linkage the electronic cloud of the O(2-) anion is strongly distorted and displaced towards X, resulting in a low negative charge in the face of the Tl atom. Consequently, the Coulombic repulsions between the lone pair and the O(2-) anions are weak. All of the Tl(2)XO(4) compounds exhibit the same open packing of A(+) cations and [XO(4)](2-) anions as their isotypic alkali counterparts.
Journal Article↗
51V magic angle spinning NMR in VOPO4 phases.
51V magic angle spinning NMR was applied to the alpha(II), beta and gamma phases of VOPO4 at three magnetic field strengths (4.7, 7.1, and 11.7 T). The 51V quadrupole and chemical shift tensors were determined by iterative fitting of the NMR lineshapes at the three magnetic field strengths. The applicability of the method is illustrated by comparison with literature data. Although determined chemical shift tensors are completely axially symmetric and of the same magnitude, all studied phases can clearly be distinguished by their quadrupole coupling tensor. Relationships between the 51V NMR data and structural characteristics such as crystal symmetries are discussed.
Crystallography↗