Chemical Composition Determination Of Francolite Apatites By Fourier Transform Infrared (FTIR) Spectroscopy

Robin M. Scheib; Raymond D. Thrasher; James R. Lehr

doi:10.1117/12.932197

29 October 1981 Chemical Composition Determination Of Francolite Apatites By Fourier Transform Infrared (FTIR) Spectroscopy

Robin M. Scheib, Raymond D. Thrasher, James R. Lehr

Author Affiliations +

Proceedings Volume 0289, 1981 Intl Conf on Fourier Transform Infrared Spectroscopy; (1981) https://doi.org/10.1117/12.932197
Event: 1981 International Conference on Fourier Transform Infrared Spectroscopy, 1981, Columbia, United States

Abstract

Prior work by Lehr and McClellan and Lehr, based on chemical, crystallographic, and x-ray diffraction studies, showed the relationship between phosphate (P) and substituted carbonate (C) in francolite apatite to be P+C = 6.00 ± 0.04 and the generalized apatite formula to be (Ca,Na,Mg) 10(PO4)6-x(CO3)xFy(F,OH)2, in which y ranges from 0.33x to 0.5x. Using the FTIR, the ratio of the area of the absorption curve for C-0 (bands in the region 1375 to 1550 cm-1) versus the area of the absorption curve for P-0 (bands in the region 530 to 690 cm-1), the "CO2 index," was found to be proportional to the mole ratio of CO3:PO4 in francolites. Stripping methods allowed the subtraction of spectral contributions of silicate and carbonate minerals and water, which would ordinarily interfere with such a determination. The study was based on 65 mineral samples and the formula was found to be: CO2 index = 0.0678 + 4.184(mole ratio CO3:PO4) (1) The correlation factor, r2, was 0.938 and the standard error of the slope ±0.136. The probability of the null hypothesis for the model was less than 0.0001.

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Robin M. Scheib, Raymond D. Thrasher, and James R. Lehr "Chemical Composition Determination Of Francolite Apatites By Fourier Transform Infrared (FTIR) Spectroscopy", Proc. SPIE 0289, 1981 Intl Conf on Fourier Transform Infrared Spectroscopy, (29 October 1981); https://doi.org/10.1117/12.932197

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