ON THE MUTUAL SOLUBILITY IN MMOO
4-LNVO
4 SYSTEMS, WHERE M = CA, CD, SR, BA, PB, LN = Y, SC, CE-LU
V. D. Zhuravlev1, O. G. Reznitskikh2, V. G. Bamburov1
1Institute of Solid State Chemistry, Ural Branch, Russian Academy of Sciences, Ekaterinburg, Russia
2Institute of High Temperature Electrochemistry, Ural Branch, Russian Academy of Sciences, Ekaterinburg, Russia
Keywords: гетеровалентные взаимозамещения, твердые растворы, энтальпия смешения, циркон, шеелит, heterovalent mutual substitutions, solid solutions, mixing enthalpy, zircon, scheelite
Abstract
The factors determining the solubility in MMoO
4(scheelite)-LnVO
4(zircon) systems, where M = Ca, Cd, Sr, Ba, Pb, Ln = Y, Sc, La-Lu, are analyzed. It is shown that primary solid solutions based on REE vanadates are absent due to a high (above 36 kJ/mol) enthalpy of polymorphic scheelite → zircon transition. For solid solutions based on bivalent metal molybdates, the zircon → scheelite transition has a lower enthalpy of 16-22.3 kJ/mol. The differences in bond ionicity in MoO
4
2- and VO
4
3- anions and interatomic distances in MO
8 and LnO
8 polyhedra restrict mutual solubility of the initial compounds, but are not the cause of its asymmetry.
DOI: 10.1134/S0022476615010114
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