Showing papers by "Daniel Louër published in 1996"
TL;DR: In this paper, a new compound with the chemical formula Th4(PO4)4P2O7, derived from the crystal structure determination, has been obtained and the unit cell parameters were obtained from powder and single-crystal X-ray diffraction data.
Abstract: The chemistry of thorium phosphate reported in the literature has been found to be erroneous. It was reconsidered in terms of careful chemical preparations and specific analytical methods. Special attention has been paid to the atom ratio value referred to r = thorium/phosphorus, which was experimentally fixed in order to obtain the correct composition of the final compound. A new compound with the chemical formula Th4(PO4)4P2O7, derived from the crystal structure determination, has been obtained. The unit cell parameters were obtained from powder and single-crystal X-ray diffraction data. It is orthorhombic (space group Pcam, Z = 2) with the cell dimensions a = 12.8646(9) A, b = 10.4374(8) A, c = 7.0676(5) A, and V = 949.00(9) A3. The atomic positions were derived from Patterson and Fourier methods and the structure was refined to an R value of 0.039. The structure consists of layers parallel to (010) containing both PO4 and P2O7 groups. These layers alternate with planes of Th atoms. The coordination sp...
107 citations
TL;DR: In this article, the nootropic drug Piracetam is known to crystallize in three phases using powder X-ray diffractometry (XRD) and differential scanning calorimetry (DSC).
49 citations
TL;DR: In this paper, the thermal decomposition process of Ce(IV) 2 (NH 4 ) 3 (NO 3 ) 6 has been determined by means of temperature-dependent X-ray diffraction and TG-DSC.
15 citations
TL;DR: In this paper, the structure of CeIIIRb2(NO3)5 · 4H2O was determined from single crystal diffraction, and the symmetry is monoclinic (space group Cc): a = 11.050, b = 8.977, c = 17.859, β = 100.877, Z = 4.
11 citations
TL;DR: In this article, the structure of two polymorphic phases of lanthanum nitrate tetrahydrate, prepared from the thermal decomposition of the hexahydrate compound, have been determined form conventional monochromatic X-ray powder diffraction data.
10 citations
6 citations
Journal Article•
6 citations
Journal Article•
3 citations
TL;DR: The structure of the low temperature stable form of 2-bromonaphthalene has been solved from laboratory X-ray powder diffraction data in this paper, where the structure is almost ordered and built of molecular layers stacked along with the long molecular axis normal to the layer.
2 citations
TL;DR: In this paper, a new compound with the chemical formula Th4(PO4)4P2O7, derived from the crystal structure determination, has been obtained and the unit cell parameters were obtained from powder and single-crystal X-ray diffraction data.
Abstract: The chemistry of thorium phosphate reported in the literature has been found to be erroneous. It was reconsidered in terms of careful chemical preparations and specific analytical methods. Special attention has been paid to the atom ratio value referred to r = thorium/phosphorus, which was experimentally fixed in order to obtain the correct composition of the final compound. A new compound with the chemical formula Th4(PO4)4P2O7, derived from the crystal structure determination, has been obtained. The unit cell parameters were obtained from powder and single-crystal X-ray diffraction data. It is orthorhombic (space group Pcam, Z = 2) with the cell dimensions a = 12.8646(9) A, b = 10.4374(8) A, c = 7.0676(5) A, and V = 949.00(9) A3. The atomic positions were derived from Patterson and Fourier methods and the structure was refined to an R value of 0.039. The structure consists of layers parallel to (010) containing both PO4 and P2O7 groups. These layers alternate with planes of Th atoms. The coordination sp...
2 citations
TL;DR: In this article, les progres survenus dans le domaine de la diffraction par les poudres au cours des vingt dernieres annees sont presentes.
Abstract: Les progres survenus dans le domaine de la diffraction par les poudres au cours des vingt dernieres annees sont presentes. Apres une analyse des facteurs a l'origine du probleme majeur du recouvrement des raies de diffraction, les moyens pour y remedier sont passes en revue. Ils comprennent les methodes de modelisation, de reconstruction geometrique du reseau reciproque et les ameliorations dans le domaine de la resolution instrumentale obtenues avec des sources de rayons X monochromatiques et le rayonnement synchrotron. Une analyse des developpements survenus dans la determination structurale ab initio a partir de donnees de diffraction par la poudre est presentee et la precision obtenue est discutee.