resumo
Magnesium whitlockite (Mg-WH, Ca18Mg2(HPO4)(2)(PO4)(12)) is a promising candidate for biomedical application in bone regeneration; however, the fabrication of Mg-WH bioceramics by conventional methods is limited. Mg-WH is known to be thermally unstable and decomposes upon heating. The mechanism of thermal decomposition and phase evolution has not comprehensively been investigated so far. In the present work, Mg-WH was synthesized by a dissolution-precipitation process under hydrothermal conditions. Thermally induced degradation of the synthesized powders was investigated in detail by combining X-ray diffraction (XRD) analysis, infrared spectroscopy (FTIR), Raman spectroscopy as well as H-1 and P-31 solid-state nuclear magnetic resonance (NMR). The as-prepared Mg-WH powders were annealed at different temperatures in the range from 400 to 1300 & DEG;C. It was found that thermal decomposition starts at around 700 & DEG;C with the formation of beta-tricalcium phosphate (& beta;-TCP, Ca-3(PO4)(2)) and a mixture of two Ca2P2O7 polymorphs. Thermal decomposition occurs gradually and the co-existence of both Mg-WH and Mg-substituted & beta;-TCP phases was observed in a wide temperature range up to 1200 & DEG;C. Complete disappearance of the HPO42- structural unit was confirmed only after annealing at 1300 & DEG;C followed by melting at 1400 & DEG;C.
palavras-chave
PHASE-TRANSFORMATION; CALCIUM PHOSPHATES; BONE; HYDROXYAPATITE; NANOPARTICLES
categoria
Chemistry; Crystallography
autores
Kizalaite, A; Klimavicius, V; Balevicius, V; Niaura, G; Salak, AN; Yang, JC; Cho, SH; Goto, T; Sekino, T; Zarkov, A
nossos autores
Projectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This research was funded by a grant WHITCERAM (No. S-LJB-22-1) from the Research Council of Lithuania and supported by the Joint Research Projects under the Bilateral Program (JSPS), RCL JSPS, No. 120224202. The research done in the University of Aveiro was supported by the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC). V. K., V. B., and G. N. gratefully acknowledge the Center of Spectroscopic Characterization of Materials and Electronic/Molecular Processes (SPECTROVERSUM Infrastructure) for the use of Raman and NMR spectrometers. The authors sincerely acknowledge Dr. Justina Gaidukevic (Vilnius University) for technical assistance.