title: High-temperature elastic moduli of flux-grown α-GeO2 single crystal.
abstract: From high-precision Brillouin spectroscopy measurements, six elastic constants (C11, C33, C44, C66, C12, and C14) of a flux-grown GeO2 single crystal with the α-quartz-like structure are obtained in the 298-1273 K temperature range. High-temperature powder X-ray diffraction data is collected to determine the temperature dependence of the lattice parameters and the volume thermal expansion coefficients. The temperature dependence of the mass density, ρ, is evaluated and used to estimate the thermal dependence of its refractive indices (ordinary and extraordinary), according to the Lorentz-Lorenz equation. The extraction of the ambient piezoelectric stress contribution, e11, from the C'11-C11 difference gives, for the piezoelectric strain coefficient d11 , a value of 5.7(2) pC N(-1), which is more than twice that of α-quartz. As the quartz structure of α-GeO2 remains stable until melting, piezoelectric activity is observed until 1273 K.
authors.affiliation: Institut Charles Gerhardt Montpellier, UMR 5253, CNRS-UM2-ENSCM-UM1, C2M, Université Montpellier 2, CC 1504, Place Eugène Bataillon, 34095 Montpellier Cédex 5 (France), Fax: (+33) 467144290.
authors.forename: Adrien
authors.initials: A
authors.lastname: Lignie
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Pascale
authors.initials: P
authors.lastname: Armand
authors.forename: Benoit
authors.initials: B
authors.lastname: Rufflé
authors.forename: Richard
authors.initials: R
authors.lastname: Mayet
authors.forename: Jerôme
authors.initials: J
authors.lastname: Debray
authors.forename: Patrick
authors.initials: P
authors.lastname: Hermet
authors.forename: Bertrand
authors.initials: B
authors.lastname: Ménaert
authors.forename: Philippe
authors.initials: P
authors.lastname: Thomas
authors.forename: Philippe
authors.initials: P
authors.lastname: Papet
keywords: Brillouin spectroscopy; X-ray diffraction; elastic constants; germanium oxide; single crystal