Crystal chemistry of REEXO4 compounds (X = P, As, V). II. Review of REEXO4 compounds and their stability fields

Author(s)

Uwe Kolitsch, D Holtstam

Abstract

A comprehensive critical review of the phase fields, metastable

modifications, solid solution ranges and phase transitions of monazite-

and zircon-type REEXO₄ (X = P, As, V) compounds is given. Monazite-type REEPO₄,

compounds are stable for REE = La to Gd and metastable for Th to IIo;

zircon-type members exist for REE = Gd to Lu, and Y, Sc. REEAsO₄,

compounds with monazite-type structure exist for REE = La to Nd, while

zircon-type compounds are known for REE = Pm to Lu, and Y, Sc; no

metastable arsenate members are known. The only stable monazite-type

REEVO₄, is LaVO₄, but metastable members are known for REE = Ce to Nd. Zircon-type REEVO₄

compounds are stable for REE = Ce to Lu, and Y, Sc, and metastable for

REE = La. Solid solution series are complete only if minor size

differences exist between REE³⁺ or X⁵⁺ cations in

respective end-members. Phase transitions occur under pressure (zircon →

(monazite →)) scheelite) and at very low temperatures. The evaluation

of the metastable phase fields and of naturally occurring members

suggests that metastable modifications of REEXO₄ compounds

can occur in nature under certain conditions (formation at temperatures

< ∼200-300°C; formation via hydrated precursor phases; stabilisation

Verlagsbuchhandlung, D-70176 Stuttgart.

Organisation(s)

Department of Mineralogy and Crystallography

External organisation(s)

Swedish Museum of Natural History

Journal

European Journal of Mineralogy: an international journal of mineralogy, geochemistry and related sciences

Volume

16

Pages

117-126

No. of pages

10

ISSN

0935-1221

Publication date

2004

Peer reviewed

Yes

Austrian Fields of Science 2012

1051 Geology, Mineralogy

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