Rhenium diboride's monocrystal elastic constants, 308 to 5 K.
The five independent moduli required to construct the complete monocrystal elastic modulus tensor of the hexagonal-symmetry superhard compound ReB(2) were measured from 308 to 5 K using resonant ultrasound spectroscopy on a special-texture polycrystal. This is possible because, confirmed by X-ray diffraction, the specimen measured was composed of grains with hexagonal axes parallel so that its polycrystal elastic response is identical to a monocrystal and because hexagonal-symmetry solids are elastically isotropic in the plane perpendicular to the hexagonal axis. Along the hexagonal (c) axis, C(33) (0) = 1021 GPa, nearly equal to C(11) of diamond, and consistent with the superhard properties. However, in the (softer) isotropic plane, C(11) (0) = 671 GPa, much lower than diamond. The changes of C(ij) with temperature are very small and smooth. The Debye temperature was computed to be 738 K, and using a high-temperature approximation, the Grüneisen parameter is γ = 1.7.
National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. yoko@lanl.gov
Yoko
Y
Suzuki
Jonathan B
JB
Levine
Albert
A
Migliori
Jim D
JD
Garrett
Richard B
RB
Kaner
Victor R
VR
Fanelli
Jonathan B
JB
Betts
D001896:Boron Compounds / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D055119:Elastic Modulus; D006244:Hardness; D008956:Models, Chemical; D013057:Spectrum Analysis / Q000379:methods*; D013696:Temperature; D014465:Ultrasonics
D001896:Boron Compounds; C519315:rhenium diboride