Thermal expansion of modified spinel, β-Mg2SiO4

Abstract

Thermal expansion of β-Mg2SiO4 (modified spinel; orthorhombic symmetry) was measured by the X-ray powder diffraction method in the temperature range between 20°C and 800°C. Grüneisen's theory of thermal expansion was applied to the linear and volume expansion data, and thermal expansion coefficients were obtained to be αa=9.14, αb=5.46, αc= 5.92, and αr=20.6 in unit of 10-6/K, at 293 K. Grüneisen's parameter γG —1.26 was obtained by assuming the Debye temperature to be 952 K. The magnitude of volume expansion coefficient of β-Mg2SiO4 is located between those of γ- and α-phases. β-Mg2SiO4 is found to be a significantly anisotropic material both in thermal expansion and elasticity. © 1980, The Seismological Society of Japan, The Volcanological Society of Japan, The Geodetic Society of Japan. All rights reserved.