Hostname: page-component-586b7cd67f-t7fkt Total loading time: 0 Render date: 2024-11-23T00:08:12.658Z Has data issue: false hasContentIssue false
  • English
  • Français

Enthalpies of formation of lanthanide oxyapatite phases

Published online by Cambridge University Press:  31 January 2011

A. S. Risbud ,
K. B. Helean ,
M. C. Wilding ,
P. Lu  and
A. Navrotsky
A. S. Risbud
Affiliation:
Department of Applied Physics, California Institute of Technology, MC 128–95, Pasadena, California 91125
K. B. Helean
Affiliation:
Thermochemistry Facility, Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, California 95616
M. C. Wilding
Affiliation:
Department of Geology, University of California at Davis, Davis, California 95616
P. Lu
Affiliation:
Department of Physics, Harvard University, Cambridge, Massachusetts 02138
A. Navrotsky*
Affiliation:
Thermochemistry Facility, Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, California 95616
*
a)Address all correspondence to this author.anavrotsky@ucdavis.edu
Get access

Abstract

A family of lanthanide silicates adopts an oxyapatitelike structure with structural formula Ln9.33 0.67(SiO4)6O2 (Ln = La, Sm, Nd, Gd,   = vacancy). The enthalpies of solution, ΔHS, for these materials and their corresponding binary oxides were determined by high-temperature oxide melt solution calorimetry using molten 2PbO B2O3 at 1078 K. These data were used to complete thermodynamic cycles to calculate enthalpies of formation from the oxides, ΔH0 f-oxides (kJ/mol): La9.33 0.67(SiO4)6O2 = 776.3 ± 17.9, Nd9.33 0.67(SiO4)6O2 = 760.4 ± 31.9, Sm9.33 0.67(SiO4)6O2 = 590.3 ± 18.6, and Gd9.33 0.67(SiO4)6O2 = 446.9 ± 21.9. Reference data were used to calculate the standard enthalpies of formation from the elements, ΔH0 f (kJ/mol): La9.33 0.67(SiO4)6O2 = 14611.0 ± 19.4, Nd9.33 0.67(SiO4)6O2 = 14661.5 ± 32.2, Sm9.33 0.67(SiO4)6O2 = -14561.7 ±; 20.8, and Gd9.33 0.67(SiO4)6O2 = -14402.7 ± 28.2. The formation enthalpies become more endothermic as the ionic radius of the lanthanide ion decreases.

Type
Rapid Communications
Information
Journal of Materials Research , Volume 16 , Issue 10 , October 2001 , pp. 2780 - 2783
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1Plucknett, K.P. and Wilkinson, D.S., J. Mater. Res. 10, 1387 (1995).CrossRefGoogle Scholar
2Lin, J. and Su, Q., J. Alloys Compd. 210, 159 (1994).CrossRefGoogle Scholar
3Lin, J., and Su, Q., Phys. Status Solidi (b), 196, 261 (1996).CrossRefGoogle Scholar
4Ronda, C.R., Justel, T., and Nikol, H., J. Alloys Compd. 275–277, 669 (1998).CrossRefGoogle Scholar
5Christiansen, A.N., Hazell, R.G., and Hewat, A.W., Acta Chem. Scand. 51, 37 (1997).Google Scholar
6Altenhein, F.K., Lutze, W., and Ewing, R.C., in Scientific Basis for Radioactive Waste Management V, edited by Lutze, W. (Mater. Res. Soc. Symp. Proc. 2, Pittsburgh, PA, 1982), p. 389.Google Scholar
7Wang, L.M., Cameron, M., Weber, W.J., Crowley, K.D., and Ewing, R.C., in Hydroxyapatite and Related Materials, edited by Brown, P. and Constantze, B. (CRC Press, Boca Raton, FL, 1994), p. 243.Google Scholar
8 JCPDS card no. 09-0432.Google Scholar
9Goldstein, J.I., Newbury, D.E., Echlin, P., Joy, D.C., Romig, A.D. Jr., Lyman, C.E., Fiori, C., and Lifshin, E., Scanning Electron Microscopy and X-Ray Microanalysis, 2nd ed. (Plenum Press, New York, 1992), p. 820.CrossRefGoogle Scholar
10Navrotsky, A., Phys. Chem. Miner. 24, 222 (1997).CrossRefGoogle Scholar
11McHale, J.M., Kowach, G.R., Navrotsky, A., and DiSalvo, F.J., Eur. J. Chem. 2, 1414 (1996).CrossRefGoogle Scholar
12Ellison, A.J.G. and Navrotsky, A., J. Am. Ceram. Soc. 75, 1430 (1992).CrossRefGoogle Scholar
13Takayama-Muromachi, E. and Navrotsky, A., J. Solid State Chem. 106, 349 (1993).CrossRefGoogle Scholar
14Robie, R.A., Hemingway, B.S., and Fisher, J.R., Thermodynamic Properties of Minerals and Related substances at 298.15 K and 1 Bar (105 Pascals) Pressure and at Higher Temperatures (U.S.Geol. Surv. Bull. 1452, Washington, D.C., 1979).Google Scholar
15Navrotsky, A., Ceram. Trans. (2000, in press).Google Scholar