Synthesis, crystal chemistry and physical study of a new series of rare earth phosphates with specific open structure


Auteur(s) / Author(s)

ZAKI Maria (1) ; AAMILI Ahmed (1) ; SADEL Abderrahim (1) ; ZAHIR Mohammed (1) ; EL-GHOZZI Malika (2) ; AVIGNANT Daniel (2)


Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)

(1) Laboratoire de Physico-chimie des Matériaux, Université Chouaïb Doukkali, Faculté des Sciences, BP 20, 24000 El-Jadida, MAROC
(2) Laboratoire des Matériaux inorganiques, UPRES A-6002 CNRS, Université Blaise Pascal, 63177 Aubière, FRANCE


Revue / Journal Title

Annales de Chimie Science des Matériaux,


ISSN: 0151-9107,

Vol: 26, Issue: 6,

2001-11, Pages: 35-43

Abstract :


Hexagonal rare earth phosphates with the composition LnP0 4,xKOH (Ln = Eu - Lu, Y; 0 < x ≤ 1), were prepared by coprecipitation of rare earth nitrates and potassium phosphate in basic medium. These compounds were characterized by X-ray diffraction and chemical analysis. The best crystallinity was obtained for samples heat-treated at 660-750°C in air during 24 h, in which the K content was determined to be near 1 % (wt). A Rietveld refinement of these hexagonal orthophosphates was performed in the same conditions as used for the hexagonal holmium orthophosphate reported earlier by us (rhabdophane-type, space group P6 222). It indicated that a part of KOH is incorporated in the hexagonal form and that the other part remains in an amorphous form. Between 800 and 1200°C the two forms gradually transform into a zircon-type LnP0 4 phase for Ln = Tb-Lu, Y and a monazite-type LnP0 4 phase for Ln = Eu, Gd. The infrared spectra for all these compounds were obtained by the KBr disk method.