Thermal expansion of F-Cl apatite crystalline solutions

We have studied the thermal expansion of 15 synthetic and two natural F-Cl apatite solid solutions through the calculation of unit-cell dimensions at elevated temperatures based on X-ray powder diffraction data collected from room temperature to similar to 900 degrees C at 50 to 100 degrees C intervals. Coefficients of thermal expansion for the a and c unit-cell axes show sensitivity to composition, with alpha(a), increasing by about 50% and alpha(c), decreasing by a third from chlorapatite to fluorapatite. Despite the relationships observed for a and c, the thermal expansion coefficient for unit-cell volume shows little sensitivity to composition, which can be explained only by a mutually compensating structural adjustment along the latter axes as temperature rises. Results of this study also imply that the thermodynamically ideal volumes of mixing for F-Cl apatite solid solutions observed at ambient conditions continue to at least 900 degrees C.

Title	Thermal expansion of F-Cl apatite crystalline solutions
Creator	Abraham, T.
	Hudacek, W.
	Leaman, A.
	Almer, C.
	Scott, B.
	Harlov, D.
	Altomare, C.
	Wildermuth, S.
	Medford, A.
	Morris, M.
	Tomaino, G.
	Conlon, M.
	Hovis, Guy L.
Publisher	American Mineralogist
Academic Department	Geology & Environmental Geosciences
Division	Natural Sciences
Organization	Lafayette College
Date Issued	2015
Date Available	2016-03-02T20:36:04Z
Type	Article
Language	English
Keyword	fluorapatite
	thermal expansion
	chlorapatite
	thermodynamic properties
Bibliographic Citation	Hovis, G. L., et al. (2015) "Thermal expansion of F-Cl apatite crystalline solutions." American Mineralogist 100 (5-6): 1040–1046.
Standard Identifier	Handle 10385/2087
Standard Identifier	DOI 10.2138/am-2015-5176
Permalink	http://hdl.handle.net/10385/2087
Rights Statement	In Copyright
Rights Holders	Mineralogical Society of America