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Pressure and Temperature Dependence of the Elastic Moduli of Polycrystalline MgF 2
Author(s) -
RAI C. S.,
MANGHNANI M. H.
Publication year - 1976
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.1151-2916.1976.tb09417.x
Subject(s) - crystallite , shear modulus , ion , materials science , single crystal , bulk modulus , elastic modulus , moduli , analytical chemistry (journal) , rutile , mineralogy , crystallography , thermodynamics , chemistry , composite material , physics , organic chemistry , chromatography , quantum mechanics
The pressure and temperature derivatives of the bulk ( K s ) and shear (μ) moduli of two polycrystalline MgF 2 specimens measured to 5 kbars and 200°C, using the ultrasonic pulse‐echo‐overlap method are, for specimens A and B, respectively: dK s /dP 5.06 and 5.10; dμ/dP 0.72 and 0.73; dK s /dT ‐0.160 and‐0.155 kbar/deg.; dμ/dT ‐0.092 and ‐0.088 kbar/deg. The ambient elastic modulus results are in agreement with the iso‐tropic values calculated from the previous single‐crystal experimental data and theoretically derived values based on the rigid‐ion model. The measured dK s /dP and dμ/dP are significantly higher than the corresponding theoretical values based on the rigid‐ion model calculations (the rigid‐ion model predicts negative dμ/dP). However, the measmed dK s /dT and dμ/d T are in fairly good agreement with the calculated values based on the previous single‐crystal and recent polycrystalline data of other investigators. The present results for MgF 2 are discussed in light of velocity‐density systematics for the rutile‐structured difluorides and oxides.