Skip to main content Accesibility Help

Interlaboratory study on the quantification of calcium phosphate phases by Rietveld refinement

  • Nicola Döbelin (a1)

An interlaboratory study (ILS, round robin) was conducted to assess the accuracy and precision of the phase quantification of calcium phosphate (CaP) bioceramics by X-ray diffraction (XRD) and Rietveld refinement. For that purpose, a mixture of hydroxyapatite and β-tricalcium phosphate, two CaP phases commonly used in synthetic bone graft substitutes, was prepared and sent to 12 laboratories for XRD analysis. Results from 26 different instruments were received and evaluated statistically according to ASTM E691 – 13. The statistical analysis revealed that the reproducibility standard deviation of phase quantities was approximately two times greater than the repeatability standard deviation, which is obtained by repeating the analysis on a single instrument configuration multiple times. The 95% reproducibility limit for phase quantities was R = ±1.67 wt%. The study also demonstrated that several participants overinterpreted their data in an attempt to refine crystallite sizes of the minor phase.

Corresponding author
a) Author to whom correspondence should be addressed. Electronic mail:
Hide All
ASTM E177 – 13 (2013). “Standard practice for use of the terms precision and bias in ASTM test methods,” in Annual Book of ASTM Standards (ASTM International, West Conshohocken, PA), Vol. 14.02.
ASTM E691 – 13 (2013). “Standard practice for conducting an interlaboratory study to determine the precision of a test method,” in Annual Book of ASTM Standards (ASTM International, West Conshohocken, PA), Vol. 14.02.
ASTM F1088 – 4 (2004). “Standard specification for beta-tricalcium phosphate for surgical implantation,” in Annual Book of ASTM Standards (ASTM International, West Conshohocken, PA), Vol. 13.01.
ASTM F1185 – 03 (2003). “Standard specification for composition of hydroxyapatite for surgical implants,” in Annual Book of ASTM Standards (ASTM International, West Conshohocken, PA), Vol. 13.01.
ASTM F2024 – 10 (2010). “Standard practice for X-ray diffraction determination of phase content of plasma-sprayed hydroxyapatite coatings,” in Annual Book of ASTM Standards (ASTM International, West Conshohocken, PA), Vol 13.01.
Bergmann, J., Friedel, P. and Kleeberg, R. (1998). “BGMN – a new fundamental parameters based Rietveld program for laboratory X-ray sources, it's use in quantitative analysis and structure investigations,” Commission of Powder Diffraction, International Union of Crystallography, CPD Newslett. 20, 58.
Bohner, M., Galea, L. and Doebelin, N. (2012). “Calcium phosphate bone graft substitutes: failures and hopes,” J. Eur. Ceram. Soc. 32, 26632671.
Chow, L. C. (2001). “Solubility of calcium phosphates,” in Octacalcium Phosphate, edited by Chow, L. C. and Eanes, E. D. (Karger, Basel), Vol. 18, pp. 94111.
Dickens, B., Schroeder, L. W. and Brown, W. E. (1974). “Crystallographic studies on the role of Mg as a stabilizing impurity in β-Ca3(PO4)2 I. The crystal structure of pure β-Ca3(PO4)2 ,” J. Solid State Chem. 10, 232248.
Dinnebier, R. E. and Billinge, S. J. L. (Eds.) (2008). Powder Diffraction: Theory and Practice (Royal Society of Chemistry, Cambridge).
Döbelin, N., Luginbühl, R. and Bohner, M. (2010). “Synthetic calcium phosphate ceramics for treatment of bone fractures,” Chimia 64, 723729.
Dorozhkin, S. V. (2002). “A review on the dissolution models of calcium apatites,” Prog. Cryst. Growth Charact. Mater. 44, 4561.
Dorozhkin, S. V. (2011). “Self-setting calcium orthophosphate formulations: cements, concretes, pastes and putties,” Int. J. Mater. Chem. 1, 148.
Elliott, J. C. (1994). Structure and Chemistry of the Apatites and other Calcium Orthophosphates (Elsevier, Amsterdam).
Enderle, R., Gotz-Neunhoeffer, F., Gobbels, M., Muller, F. A. and Greil, P. (2005). “Influence of magnesium doping on the phase transformation temperature of beta-TCP ceramics examined by Rietveld refinement,” Biomaterials 26, 33793384.
Gopal, R. and Calvo, C. (1972). “Structural relationship of Whitlockite and βCa3(PO4)2 ,” Nat. Phys. Sci. 237, 3032.
ICDD (2013). PDF-4+2013 (Database), edited by Dr. Soorya Kabekkodu, (International Centre for Diffraction Data, Newtown Square, PA, USA).
Ishikawa, K., Ducheyne, P. and Radin, S. (1993). “Determination of the Ca/P ratio in calcium-deficient hydroxyapatite using X-ray-diffraction analysis,” J. Mater. Sci.-Mater. Med. 4, 165168.
ISO 13175-3 (2012). Implants for surgery - Calcium phosphates - Part 3: Hydroxyapatite and beta-tricalcium phosphate bone substitutes (ISO, Geneva, Switzerland).
ISO 13779-3 (2008). Implants for surgery - Calcium phosphates - Part 3: Chemical analysis and characterization of crystallinity and phase purity (ISO, Geneva, Switzerland).
Jackson, L. E., Barralet, J. E. and Wright, A. J. (2004). “Rietveld analysis in sintering studies of Ca-deficient hydroxyapatite,” Key Eng. Mater. 254–256, 297300.
Keller, L. (1995). “X-ray powder diffraction patterns of calcium phosphates analyzed by the Rietveld method,” J. Biomed. Mater. Res. 29, 14031413.
Madsen, I. C. and Scarlett, N. V. Y. (2008). “Quantitative phase analysis” in Powder Diffraction: Theory and Practice, edited by Dinnebier, R. E. and Billinge, S. J. L. (Royal Society of Chemistry, Cambridge), pp. 298331.
McCusker, L. B., Von Dreele, R. B., Cox, D. E., Louer, D. and Scardi, P. (1999). “Rietveld refinement guidelines,” J. Appl. Crystallogr. 32, 3650.
Neira, I. S., Kolen'ko, Y. V., Lebedev, O. I., Van Tendeloo, G., Gupta, H. S., Guitián, F. and Yoshimura, M. (2009). “An effective morphology control of hydroxyapatite crystals via hydrothermal synthesis,” Cryst. Growth. Des. 9, 466474.
Neuman, W. F. and Mulryan, B. J. (1971). “Synthetic hydroxyapatite crystals IV. Magnesium incorporation,” Calcif. Tissue Res. 7, 133138.
Nilen, R. W. N. and Richter, P. W. (2008). “The thermal stability of hydroxyapatite in biphasic calcium phosphate ceramics,” J. Mater. Sci.: Mater. Med. 19, 16931702.
Raynaud, S., Champion, E., Bernache-Assolant, D. and Laval, J.-P. (2001). “Determination of calcium/phosphorus atomic ratio of calcium phosphate apatites using X-ray diffractometry,” J. Am. Ceram. Soc. 84, 359366.
Raynaud, S., Champion, E., Bernache-Assollant, D. and Thomas, P. (2002a). “Calcium phosphate apatites with variable Ca/P atomic ratio I. Synthesis, characterisation and thermal stability of powders,” Biomaterials 23, 10651072.
Raynaud, S., Champion, E. and Bernache-Assollant, D. (2002b). “Calcium phosphate apatites with variable Ca/P atomic ratio II. Calcination and sintering,” Biomaterials 23, 10731080.
Reid, J. W. and Hendry, J. A. (2006). “Rapid, accurate phase quantification of multiphase calcium phosphate materials using Rietveld refinement,” J. Appl. Crystallogr. 39, 536543.
Riboud, P. V. (1973). “Composition et stabilité des phases a structure d'apatite dans le système CaO-P2O5-oxyde de Fer-H2O a haute temperature,” Ann. Chim. 8, 381390.
Rietveld, H. M. (1969). “A profile refinement method for nuclear and magnetic structures,” J. Appl. Crystallogr. 2, 6571.
Schroeder, L. W., Dickens, B. and Brown, W. E. (1977). “Crystallographic studies of the role of Mg as a stabilizing impurity in β-Ca3(PO4)2 II. Refinement of Mg-containing β-Ca3(PO4)2 ,” J. Solid State Chem. 22, 253262.
Stutzman, P. (2005). “Powder diffraction analysis of hydraulic cements: ASTM Rietveld round-robin results on precision,” Powder Diffr. 20, 97100.
Sudarsanan, K. and Young, R. A. (1969). “Significant precision in crystal structure details: Holly springs hydroxyapatite,” Acta Crystallogr. B25, 15341543.
Tõnsuaadu, K., Gross, K. A., Plusuma, L. and Veiderma, M. (2012). “A review on the thermal stability of calcium apatites,” J. Therm. Anal. Calorim. 110, 647659.
Toth, J. M., Hirthe, W. M., Hubbart, W. G., Brantley, W. A. and Lynch, K. L. (1991). “Determination of the ratio of HA/TCP mixtures by x-ray diffraction,” J. Appl. Biomater. 2, 3740.
Welch, J. H. and Gutt, W. (1961). “High-temperature studies of the system calcium oxide-phosphorus pentoxide,” J. Chem. Soc. 874, 44424444.
Wilson, R. M., Elliott, J. C., Dowker, S. E. P. and Rodriguez-Lorenzo, L. M. (2005). “Rietveld refinements and spectroscopic studies of the structure of Ca-deficient apatite,” Biomaterials 26, 13171327.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Powder Diffraction
  • ISSN: 0885-7156
  • EISSN: 1945-7413
  • URL: /core/journals/powder-diffraction
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed