Effect of pH level and calcination on the production of calcium phosphates by acidic route of wet precipitation

• Published in: Cerâmica 2021-06, Vol.67 (382), p.236-243
• Main Authors: Neves, J. G., Navarro da Rocha, D., Lopes, C. C., Prado da Silva, M. H., Sinhoreti, M. A. C., Correr-Sobrinho, L., Fraga, M. A. A., Correr, A. B.
• Format: Magazinearticle
• Language: English
• Subjects: brushite; Calcium phosphates; calcium pyrophosphate; Chelating agents; Chelation; Heat treatment; Hydroxyapatite; Lactic acid; MATERIALS SCIENCE, CERAMICS; Morphology; Roasting; Room temperature; Synthesis; β-TCP
• ISSN: 0366-6913; 1678-4553; 1678-4553
• DOI: 10.1590/0366-69132021673822965

Multiphasic calcium phosphate powders were synthesized by the acidic route, using lactic acid as a chelating agent that allows the production of a stable and rich solution of calcium and phosphate ions at room temperature. After pH adjusting, without varying the concentrations of precursor solution, XRD and FTIR analyses showed different CaP phases before and after heat treatment at 1000 °C. At pH 5, brushite plate-like particles were produced, while at higher pH levels (7 to 12) nano-hydroxyapatite particles were formed. After the calcination process, partial and total decomposition of hydroxyapatite in the β-TCP phase was explained by XRF analysis due to the calcium-deficient hydroxyapatite of synthesized samples at pH 7 and 10. This work presents an important method to synthesize any desired CaP phase compositions by varying the pH level and subsequently performing heat treatment, which has a direct effect on morphology, crystallinity, and formation of different CaP powders.