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Solid Solubility and Polymorphism in the System Sr 2 SiO 4 ‐Sr 2 GeO 4 ‐Ba 2 GeO 4 ‐Ba 2 SiO 4
Author(s) -
PIEPER G.,
EYSEL W.,
HAHN Th.
Publication year - 1972
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.1151-2916.1972.tb13455.x
Subject(s) - monoclinic crystal system , solubility , solid solution , enthalpy , polymorphism (computer science) , crystallography , x ray crystallography , diffraction , crystal structure , lattice constant , analytical chemistry (journal) , materials science , powder diffraction , chemistry , mineralogy , thermodynamics , physics , optics , biochemistry , chromatography , gene , genotype , metallurgy
The reciprocal salt pair Sr 2 SiO 4 ‐Sr 2 GeO 4 ‐Ba 2 GeO 4 ‐Ba 2 SiO 4 was investigated using X‐ray powder diffraction and DTA. Unlimited solubility in the low‐K 2 SO 4 structure type (α′) occurs throughout the system above 85°C. The nonlinear changes of some lattice constants of the solid solutions are discussed. A stable monoclinic low‐temperature (β) form of Sr 2 SiO 4 was found which converts reversibly to the high‐temperature α′‐modification at 85°C. The enthalpy of the β‐α’ transition is 51 cal/mol. In the reciprocal salt pair the β‐form solid solutions occur in a very narrow region below 85°C.