Jeanloz R, Ahrens TJ, Mao HK, Bell PM. B1-B2 Transition in Calcium Oxide from Shock-Wave and Diamond-Cell Experiments.
Science 1979;
206:829-30. [PMID:
17820761 DOI:
10.1126/science.206.4420.829]
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Abstract
Volume and structural data obtained by shock-wave and diamond-cell techniques demonstrate that calcium oxide transforms from the B1 (sodium chloride type) to the B2 (cesium chloride type) structure at 60 to 70 gigapascals (0.6 to 0.7 megabar) with a volume decrease of 11 percent. The agreement between the shockwave and diamond-cell results independently confirms the ruby-fluorescence pressure scale to about 65 gigapascals. The shock-wave data agree closely with ultrasonic measurements on the B1 phase and also agree satisfactorily with equations of state derived from ab initio calculations. The discovery of this B1-B2 transition is significant in that it allows considerable enrichment of calcium components in the earth's lower mantle, which is consistent with inhomogeneous accretion theories.
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