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The Stability of Bredigite and Other Ca‐Mg Silicates
Author(s) -
ESSENE ERIC
Publication year - 1980
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.1151-2916.1980.tb10213.x
Subject(s) - limit (mathematics) , stability (learning theory) , thermodynamics , invariant (physics) , phase space , mineralogy , chemistry , high pressure , boundary (topology) , phase (matter) , physics , materials science , mathematical analysis , mathematics , mathematical physics , computer science , organic chemistry , machine learning
The phase Ca 7 Mg(SiO 4 ) 4 , bredigite, is chemically and structurally distinct from α‐Ca 2 SiO 4 . Experiments on its lower stability limit represent a synthesis limit which is not likely to be an equilibrium boundary. Equilibrium experiments place its upper stability limit at 1372°C and 98 kPa by the reactionThe experimental data also require a second reactionat the same pressure and temperature and imply that two other reactions relating these phases are located near 1372°C and 98 kPa. Location of these four reactions around an invariant point in P‐T space shows that bredigite is on the low‐pressure side of the reactions.