A high pressure raman study of ThO2 to 40 GPa and pressure-induced phase transition from fluorite structure |
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| Authors: | A Jayaraman G A Kourouklis L G van Uitert |
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| Affiliation: | (1) Present address: AT&T Bell Laboratories, Murray Hill, 07974 New Jersey, USA;(2) Present address: Department of Physics, National Technical University, Zografou Campus, 15773 Athens GR, Greece |
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| Abstract: | The pressure dependence of the first-order Raman peak and two second-order Raman features of ThO2 crystallizing in the fluorite-type structure is investigated using a diamond anvil cell, up to 40GPa. A phase transition from the fluorite phase is observed near 30 GPa as evidenced by the appearance of seven new Raman peaks. The high pressure phases of ThO2 and CeO2 exhibit similar Raman features and from this it is believed that the two structures are the same, and have the PbCl2-type structure. The pressure dependence dω/dP of the observed phonons and their mode Grüneisen parameters are similar to the isostructural CeO2. The observed second-order Raman features are also identified from the calculated phonon dispersion curves for ThO2. |
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| Keywords: | High pressure Raman spectra pressure-induced phase transition thorium dioxide fluorite structure |
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