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The compression behavior of the hexagonal AlB2 phase of Hafnium Diboride (HfB2) was studied in a diamond anvil cell to a pressure of 208 GPa by axial X-ray diffraction employing platinum as an internal pressure standard. The deformation behavior of HfB2 was studied by radial X-ray diffraction technique to 50 GPa, which allows for measurement of maximum differential stress or compressive yield strength at high pressures. The hydrostatic compression curve deduced from radial X-ray diffraction measurements yielded an ambient-pressure volume V0 = 29.73 Å3/atom and a bulk modulus K0 = 282 GPa. Density functional theory calculations showed ambient-pressure volume V0 = 29.84 Å3/atom and bulk modulus K0 = 262 GPa, which are in good agreement with the hydrostatic experimental values. The measured compressive yield strength approaches 3% of the shear modulus at a pressure of 50 GPa. The theoretical strain-stress calculation shows a maximum shear stress τmax~39 GPa along the (1−10) [110] direction of the hexagonal lattice of HfB2, which thereby can be an incompressible high strength material for extreme-environment applications.
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A simple wire-coil resistive heater for high temperature radial x-ray diffraction in a diamond anvil cell
Diamond anvil cells are commonly used at synchrotron x-ray diffraction beamlines to study structural and thermoelastic properties of materials at high pressures. In a radial geometry, where the x-ray probe is oriented perpendicular to the axis of force, the deformation and strength of materials can be measured in situ. Because the anelastic and failure properties of materials depend strongly on temperature, many applications would benefit from the ability to measure high pressure radial diffraction in elevated and accurately controlled thermal environments. Previous work to introduce high temperature to radial diamond anvil cells has been largely limited to laser heating, with relatively scant efforts to resistively heat the sample. Here, we report a relatively straightforward adaptation of a simple wire coil heater, with in situ high-temperature radial diffraction performed on tungsten carbide up to 573 K at beamline 12.2.2 of the Advanced Light Source. The results demonstrate that the differential stress supported by WC decreases with increasing temperature: the differential stress on the basal (001) and pyramidal (101) planes decreased 6.6% and 5.5%, respectively, while the (100) plane only saw a 2.7% decrease, in agreement with previous studies.
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- Award ID(s):
- 2017294
- PAR ID:
- 10667571
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- Review of Scientific Instruments
- Volume:
- 97
- Issue:
- 1
- ISSN:
- 0034-6748
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1063/5.0293861
