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Science 16 November 1979:
Vol. 206. no. 4420, pp. 829 - 830
DOI: 10.1126/science.206.4420.829
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Articles

B1-B2 Transition in Calcium Oxide from Shock-Wave and Diamond-Cell Experiments

RAYMOND JEANLOZ 1, T. J. AHRENS 1, H. K. MAO 2, and P. M. BELL 2

1 Seismological Laboratory, California Institute of Technology, Pasadena 91125
2 Carnegie Institution of Washington, Washington, D.C. 20008

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.

Submitted on May 21, 1979


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Dynamic Compression of Earth Materials.
T. J. Ahrens and T. J. Ahrens (1980)
Science 207, 1035-1041
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Science. ISSN 0036-8075 (print), 1095-9203 (online)