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Phase Relations and Volume Changes of Hafnia under High Pressure and High Temperature
Author(s) -
Ohtaka Osamu,
Fukui Hiroshi,
Kunisada Taichi,
Fujisawa Tomoyuki,
Funakoshi Kenichi,
Utsumi Wataru,
Irifune Tetsuo,
Kuroda Koji,
Kikegawa Takumi
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00843.x
Subject(s) - hafnia , orthorhombic crystal system , tetragonal crystal system , compressibility , high pressure , materials science , phase (matter) , phase transition , bulk modulus , volume (thermodynamics) , synchrotron radiation , thermodynamics , compression (physics) , analytical chemistry (journal) , mineralogy , crystallography , chemistry , composite material , crystal structure , optics , cubic zirconia , ceramic , physics , organic chemistry , chromatography
Using multi‐anvil high‐pressure devices and synchrotron radiation, X‐ray in situ observations of HfO 2 under high pressure and high temperature have been performed to investigate its phase relations and compression behavior. An orthorhombic phase (orthoI) is stable from 4 to 14.5 GPa below 1250°–1400°C and transforms to a tetragonal phase, which is one of the high‐temperature forms of HfO 2 , above these temperatures. Another orthorhombic phase (orthoII) with a cotunnite‐type structure appears above 14.5 GPa. OrthoII is stable up to 1800°C at 21 GPa. OrthoII is quenchable to ambient conditions. The orthoI‐to‐orthoII transition is accompanied by ∼8 vol% decrease. The bulk moduli of orthoI and orthoII at room temperature are 220 and 312 GPa, respectively. This low compressibility of orthoII indicates that it is a potential candidate for very hard materials.