ISSN:
1432-2021
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Abstract The adiabatic single-crystal elastic constants, C ij , of stoichiometric magnesium aluminate spinel (MgAl2O4) have been measured up to 1273 K by highresolution Brillouin spectroscopy, using a 6-pass tandem Fabry-Pérot interferometer and an argon ion laser (514.5 nm). Two platelet samples were employed for probing the acoustic phonons along [100] and [110] directions by platelet and backscattering geometries. The measured temperature dependences of the elastic moduli show a distinct anomaly at 923 K in the shear modulus C s = (C11-C12)/2 (along [110] direction) and the longitudinal modulus C11 (along [100] direction). This anomaly is consistent with the order-disorder phase transition, resulting from the atomic exchange between Mg at the tetrahedral site and Al at the octahedral site, which has been well documented recently (Peterson et al. 1991; Millard et al. 1992) by neutron powder diffraction and 27Al magic-angle spinning NMR. The values of the temperature derivatives of v p , v s , and K s , in the temperature range 300–923 K, calculated by the Voigt-Reuss-Hill approximation are -0.40ms−1 K−1, -0.26ms−1 K−1, and -1.89 x 10−2GPaK−1.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00203051
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