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Reinvestigation of the System Na 3 AlF 6 ‐Li 3 AlF 6
Author(s) -
GARTON G.,
WANKLYN B. M.
Publication year - 1967
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1967.tb15142.x
Subject(s) - eutectic system , solid solution , phase diagram , chemistry , solubility , annealing (glass) , analytical chemistry (journal) , atmospheric temperature range , thermodynamics , phase (matter) , mineralogy , crystallography , microstructure , chromatography , physics , organic chemistry
A partial phase diagram for the system Na 3 AlF 6 ‐Li 3 AlF 6 was constructed from DTA and X‐ray diffraction measurements. A region of solid solution extends from Na 3 AlF 6 to the limiting composition Na 2 LiAlF 6 . At compositions between Na 1.5 Li 1.5 AlF 6 and NaLi 2 AlF 6 a cubic phase resembling the mineral cryolithionite is stable over a narrow range of temperatures, which shifts progressively to higher temperatures with increasing lithium content. A single phase can be quenched from samples annealed within this range except near the ideal cryolithionite composition (Na 1.5 Li 1.5 AlF 6 ) where the upper temperature limit is too low to permit recombination of two solid phases to cryolithionite even with prolonged annealing. Cryolithionite precipitated from aqueous solution, a sample of the mineral, and the solid solutions containing from 53 to 65 mole % Li 3 AlF 6 have identical powder patterns except for differences of lattice constants. Solid solubility of Na 3 AlF 6 in Li 3 AlF 6 reaches 30 mole % at the eutectic temperature.