Abstract
Atomic positional disorder of a single-phase natural carbonate fluorapatite (francolite) is revealed from analysis of the atomic displacement parameters (ADPs) refined from neutron powder diffraction data as a function of temperature and carbonate content. The ADPs of the francolite show a strong disturbance at the P, O3, and F sites. When it is heat treated to partially or completely remove the carbonate, the ADPs as well as the other structural parameters resemble those of a fluorapatite (Harding pegmatite) that was measured under the same conditions. The various structural changes are consistent with a substitution mechanism whereby the planar carbonate group replaces a phosphate group and lies on the mirror plane of the apatite structure.
Original language | English |
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Pages (from-to) | 511-517 |
Number of pages | 7 |
Journal | Journal of Materials Research |
Volume | 15 |
Issue number | 2 |
DOIs | |
State | Published - Feb 2000 |
Funding
This work was supported by a Southeastern Universities Research Association–Oak Ridge National Laboratory Cooperative Program and the Division of Sponsored Research of Florida Atlantic University. Oak Ridge National Laboratory is supported by the Division of Materials Sciences, United States Department of Energy (Contract No. DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation).