%0 Journal Article
%T Study of Ga3+-induced hydrothermal crystallization of a alpha-quartz type Ga1-xFexPO4 single crystal by in-situ X-ray Absorption Spectroscopy (XAS)
%+ Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM)
%+ Laboratoire Charles Coulomb (L2C)
%+ Institut Nanosciences et Cryogénie (INAC)
%+ Matériaux, Rayonnements, Structure (NEEL - MRS)
%A Manhal, Souleiman
%A Cambon, Olivier
%A Haidoux, A.
%A Haines, Julien
%A Levelut, Claire
%A Ranieri, Vincent
%A Hazemann, Jean-Louis
%< avec comité de lecture
%Z L2C:12-184
%@ 0020-1669
%J Inorganic Chemistry
%I American Chemical Society
%V 51
%N 21
%P 11811-11819
%8 2012-10-11
%D 2012
%R 10.1021/ic3017485
%Z Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci]Journal articles
%X The dissolution of α-FePO4 and the α-Ga0.75Fe0.25PO4 solid solution with α-quartz-type structures under hydrothermal conditions in 1 M HNO3 aqueous solution was investigated by in situ X-ray absorption spectroscopy (XAS) at the Fe K-edge. The solubility of α-FePO4 increases with temperature and is higher at 25 MPa than at 50 MPa. The Fe3+ cation in solution is 6-fold coordinated with an average Fe-O distance close to 2.0 Å. A similar experiment was performed with a solid solution of α-quartz-type Ga0.75Fe0.25PO4 as the starting phase under a pressure of 25 MPa. By varying the temperature from 303 K up to 573 K a single crystal was grown with 23% Fe3+ with the α-quartz-type structure. These results show that the crystallization of pure α-quartz-type FePO4 by the hydrothermal method is not possible due to the formation of very stable Fe3+ hexa-aquo complexes [Fe(H2O)6]3+ and to the absence of FeO4 tetrahedra in solution. Ga3+ cations in solution induce the formation of gallophosphate complexes at the solid-liquid interface, which are at the origin of the nuclei for crystallization. We propose a crystallization mechanism in which the Fe3+ substitutes Ga3+ with a 4-fold coordination in mixed (iron/gallo)-phosphate complexes that leads to the growth of an α-quartz-type Ga0.77Fe0.23PO4 single crystal.
%G English
%L hal-00743721
%U https://hal.science/hal-00743721
%~ CEA
%~ UGA
%~ CNRS
%~ UNIV-GRENOBLE1
%~ UNIV-MONTP1
%~ UNIV-MONTP2
%~ ENSC-MONTPELLIER
%~ INPG
%~ NEEL
%~ ICG
%~ L2C
%~ DSM-INAC
%~ INC-CNRS
%~ NEEL-MRS
%~ MIPS
%~ CHIMIE
%~ UNIV-MONTPELLIER
%~ CEA-DRF
%~ IRIG
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%~ UM-2015-2021