Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Johnson, M. C. Articles by Jones, R. L. Search for Related Content GeoRef GeoRef Citation

Thermal decomposition of rhombohedral KClO₃ from 29–76 kilobars and implications for the molar volume of fluid oxygen at high pressures

¹ Department of Geography and Environmental Engineering, United States Military Academy, West Point, New York 10996, U.S.A.
² Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, U.S.A.
³ CLRC Daresbury Laboratory, Warrington, WA4 4AD, U.K.

Correspondence: ^* E-mail: marie-johnson{at}usma.edu

KClO₃ thermal decomposition has been studied from 29–76 kilobars using a multianvil high-pressure device and in-situ energy-dispersive X-ray diffraction and off-line quenching experiments. The rhombohedral form of KClO₃ was found to decompose to the B2 form of KCl and O₂ via an orthorhombic KClO₄ intermediate over this pressure interval. The decomposition temperature was found to vary only slightly with pressure. The online experiments gave decomposition temperatures between 500 and 580 °C. Further off-line quenching experiments using sealed gold tubes determined the equilibrium decomposition boundary to be 550 ± 15 °C over this pressure range. Unit-cell parameters and volumes were determined for the high-pressure phases of KClO₃ and KCl from the diffraction data. The partial molar volume of O₂ was calculated from the difference in the solid volumes. Oxygen fluid volumes were then calculated along the decomposition boundary and vary from 10.6 ± 0.2 cm³/mol at 29 kbar to 9.6 ± 0.1 cm³/mol at 76 kbar. These volumes are 30 to 50% less than previous estimates determined from shock wave data, and imply that oxygen can be more easily stored in Earth’s mantle and core than previously believed. The thermal equation of state of the B2 form of KCl was investigated online using NaCl as an internal pressure standard. KCl was then used as an internal pressure calibrant for the online KClO₃ decomposition experiments. The mechanical behavior of the multianvil high-pressure device was also studied and load vs. force characteristics are presented here.

This article has been cited by other articles:

				D. Walker, D. Walker, P. K. Verma, L. M.D. Cranswick, R. L. Jones, S. M. Clark, and S. Buhre Halite-sylvite thermoelasticity American Mineralogist, January 1, 2004; 89(1): 204 - 210. [Abstract] [Full Text] [PDF]

				D. Walker, L. M.D. Cranswick, P. K. Verma, S. M. Clark, and S. Buhre Thermal equations of state for B1 and B2 KCl American Mineralogist, July 1, 2002; 87(7): 805 - 812. [Abstract] [Full Text] [PDF]