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Vitreous forsterite (Mg 2 SiO 4 ): Synthesis, structure, and thermochemistry
Author(s) -
Tangeman Jean A.,
Phillips Brian L.,
Navrotsky Alexandra,
Weber J. K. Richard,
Hixson April D.,
Key Thomas S.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl012222
Subject(s) - forsterite , calorimetry , supercooling , thermochemistry , materials science , nucleation , crystallization , octahedron , crystallography , mineralogy , enthalpy , crystal (programming language) , cristobalite , crystal structure , thermodynamics , chemistry , metallurgy , quartz , physics , computer science , programming language
Here we report the first synthesis of a forsterite (Mg 2 SiO 4 ) composition glass as an essentially phase‐pure bulk material. Under containerless conditions, with heterogeneous nucleation sites minimized, glass forms by cooling ca. 1 mm liquid Mg 2 SiO 4 droplets in oxygen at 700 K/s. 29 Si NMR spectroscopic data indicate that the SiO 4 tetrahedra and MgO 6 octahedra exist in a corner sharing arrangement in the glass, but upon crystallization the polyhedral units reorganize to form edge‐sharing linkages. Transposed temperature drop calorimetry shows that the glass is 61.4±1.3 kJ/mol higher in enthalpy than the crystal.