Abstract:
:We predict by first principles a phase transition in alumina at approximately 3.7 Mbar and room temperature from the CaIrO(3)-type polymorph to another with the U(2)S(3)-type structure. Because alumina is used as window material in shock-wave experiments, this transformation should be important for the analysis of shock data in this pressure range. Comparison of our results on all high-pressure phases of alumina with shock data suggests the presence of two phase transitions in shock experiments: the corundum to Rh(2)O(3)(II)-type structure and the Rh(2)O(3)(II)-type to CaIrO(3)-type structure. The transformation to the U(2)S(3)-type polymorph is in the pressure range reached in the mantle of recently discovered terrestrial exoplanets and suggests that the multi-megabar crystal chemistry of planet-forming minerals might be related to that of the rare-earth sulfides.
journal_name
Proc Natl Acad Sci U S Aauthors
Umemoto K,Wentzcovitch RMdoi
10.1073/pnas.0711925105subject
Has Abstractpub_date
2008-05-06 00:00:00pages
6526-30issue
18eissn
0027-8424issn
1091-6490pii
0711925105journal_volume
105pub_type
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