TY  - JOUR
A1  - Haussühl, Eiken
A1  - Reichmann, Hans Josef
A1  - Schreuer, Jürgen
A1  - Friedrich, Alexandra
A1  - Hirschle, Christian
A1  - Bayarjargal, Lkhamsuren
A1  - Winkler, Björn
A1  - Alencar, Igor
A1  - Wiehl, Leonore
A1  - Ganschow, Steffen
T1  - Elastic properties of single crystal Bi₁₂SiO₂₀ as a function of pressure and temperature and acoustic attenuation effects in Bi₁₂MO₂₀ (M = Si, Ge and Ti)
T2  - Materials Research Express
N2  - A comprehensive study of sillenite Bi12SiO20 single-crystal properties, including elastic stiffness and piezoelectric coefficients, dielectric permittivity, thermal expansion and molar heat capacity, is presented. Brillouin-interferometry measurements (up to 27 GPa), which were performed at high pressures for the first time, and ab initio calculations based on density functional theory (up to 50 GPa) show the stability of the sillenite structure in the investigated pressure range, in agreement with previous studies. Elastic stiffness coefficients c11 and c12 are found to increase continuously with pressure while c44 increases slightly for lower pressures and remains nearly constant above 15 GPa. Heat-capacity measurements were performed with a quasi-adiabatic calorimeter employing the relaxation method between 2 K and 395 K. No phase transition could be observed in this temperature interval. Standard molar entropy, enthalpy change and Debye temperature are extracted from the data. The results are found to be roughly half of the previous values reported in the literature. The discrepancy is attributed to the overestimation of the Debye temperature which was extracted from high-temperature data. Additionally, Debye temperatures obtained from mean sound velocities derived by Voigt-Reuss averaging are in agreement with our heat-capacity results. Finally, a complete set of electromechanical coefficients was deduced from the application of resonant ultrasound spectroscopy between 103 K and 733 K. No discontinuities in the temperature dependence of the coefficients are observed. High-temperature (up to 1100 K) resonant ultrasound spectra recorded for Bi12MO20 crystals revealed strong and reversible acoustic dissipation effects at 870 K, 960 K and 550 K for M = Si, Ge and Ti, respectively. Resonances with small contributions from the elastic shear stiffness c44 and the piezoelectric stress coefficient e123 are almost unaffected by this dissipation.
Y1  - 2020
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/86393
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-863939
SN  - 2053-1591
VL  - 7
IS  - 2. 025701
PB  - IOP Publishing
CY  - Bristol
ER  -