Synthesis of Hf8O7, a new binary hafnium oxide, at high pressures and high temperatures
- Goethe Univ., Frankfurt (Germany). Inst. of Geosciences
- Dassault Systemes, Cambridge (United Kingdom). BIOVIA
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
In this paper, two binary phases in the system Hf-O have been synthesized at pressures between 12 and 34 GPa and at temperatures up to 3000 K by reacting Hf with HfO2 using a laser-heated diamond anvil cell. In situ X-ray diffraction in conjunction with density functional theory calculations has been employed to characterize a previously unreported tetragonal Hf8O7 phase. This phase has a structure which is based on an fcc Hf packing with oxygen atoms occupying octahedral interstitial positions. Its predicted bulk modulus is 223(1) GPa. The second phase has a composition close to Hf6O, where oxygen atoms occupy octahedral interstitial sites in an hcp Hf packing. Its experimentally determined bulk modulus is 128(30) GPa. Finally, the phase diagram of Hf metal was further constrained at high pressures and temperatures, where we show that α-Hf transforms to β-Hf around 2160(150) K and 18.2 GPa and β-Hf remains stable up to at least 2800 K at this pressure.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE; German Research Foundation (DFG); German Federal Ministry of Education and Research (BMBF)
- Contributing Organization:
- Dassault Systemes, Cambridge (United Kingdom)
- Grant/Contract Number:
- AC52-06NA25396; 05KSRF1; 05K10RFA; 05K13RF1
- OSTI ID:
- 1356152
- Report Number(s):
- LA-UR-17-21517; TRN: US1702153
- Journal Information:
- High Pressure Research, Vol. 37, Issue 2; ISSN 0895-7959
- Publisher:
- Taylor & FrancisCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Hafnium oxide nanoparticles fabricated by femtosecond laser ablation in water
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journal | January 2019 |
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