Elasticity of single-crystal MgAl2O4spinel up to 1273 K by Brillouin spectroscopy

✍ Scribed by V. Askarpour; M. H. Manghnani; S. Fassbender; A. Yoneda

• Publisher: Springer-Verlag
• Year: 1993
• Tongue: English
• Weight: 777 KB
• Volume: 19
• Category: Article
• ISSN: 0342-1791
• DOI: 10.1007/bf00203051

✦ Synopsis

The adiabatic single-crystal elastic constants, Cij, of stoichiometric magnesium aluminate spinel (MgA1204) have been measured up to 1273 K by highresolution Brillouin spectroscopy, using a 6-pass tandem Fabry-P6rot 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 Cs = (Cll-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 A1 at the octahedral site, which has been well documented recently (Peterson et al. 1991 ;Millard et al. 1992) by neutron powder diffraction and 27A1 magic-angle spinning NMR. The values of the temperature derivatives of vp, Vs, and Ks, in the temperature range 300-923 K, calculated by the Voigt-Reuss-Hill approximation are -0.40 ms-1 K-1, _ 0.26 ms-1 K-1, and -1.89 x 10 -2 GPaK -1. dvL[loo]/dT --0.402+0.031 --0.228__0.052 --0.387 --0.314 --0.320 --0.396 dvrtlool/dT -0.216+0.019 -0.163___0.041 -0.180 -0.147 -0.118 --0.221 dVLmo]/dT --0.359 ___0.