Resumo

CAMPOS-QUIROS, Alexánder et al. Qualitative and quantitative X-ray diffraction analysis of calcium phosphates by Scherrer, Williamson-Hall and Rietveld refinement methods. Tecnología en Marcha [online]. 2022, vol.35, n.4, pp.104-115. ISSN 0379-3982.  http://dx.doi.org/10.18845/tm.v35i4.5664.

Calcium phosphates are important bioceramic materials used for bioactive coatings for metal implants. In the present study, calcium phosphate powders were synthesized by chemical precipitation method using Ca(NO3 ) 2 and (NH4 ) 2 HPO4 . X-ray diffraction technique was used to perform a qualitative and quantitative analysis of the crystalline phases present in the material using Scherrer, Williamson-Hall, and Rietveld methods. The sample is constituted by 75 weight % of monetite (CaHPO4 ) and 25 weight % of brushite (CaHPO4 .H2 O), with an average crystallite size within the submicrometer order. Scanning electron microscopy shows agglomerated particles, with an average size of 2,8 ± 1 µm and different morphologies. Elemental analysis by energy-dispersive X-ray spectroscopy revealed an average calcium/phosphorus (Ca/P) molar ratio of 0.95, which is consistent with monetite and brushite phases. Finally, the presence of both phases is mainly attributed to the low pH during the reaction and the drying process after the synthesis.

Palavras-chave : Brushite; calcium phosphate; monetite; chemical precipitation; Rietveld method.

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