Papers by Author: Tobias J. Brunner

Abstract: X-ray amorphous tricalcium-phosphate nanoparticles (ATCP) produced by flame spray synthesis were heat-treated at temperatures between 500 and 1000 °C and analyzed in situ by X-ray powder diffraction. The main phase occurring after crystallisation at 525 °C was α-TCP, minor phases were identified as β-TCP and hydroxyapatite. More elevated temperatures induced crystallite growth and the transformation of α-TCP into β-TCP. Above 900 °C no α-TCP was traceable anymore. α’-TCP was not observed in the experiment. This study shows that nanoparticulate α-TCP can be obtained by thermal treatment of an amorphous TCP nanoparticle in a temperature range where sintering effects such as particle growth and densification are moderate or nearly negligible.

Abstract: The effect of composition on the reactivity of a calcium phosphate cement (CPC) made of tricalcium phosphate (TCP) – water mixtures was investigated by isothermal calorimetry at 37°C. The parameters of interest were the mean particle size of the powder, the use of small amounts of nanosized hydroxyapatite powder, and the phosphate concentration and the pH of the aqueous solution. The results could be well explained by theoretical considerations. The main parameter controlling CPC reactivity was TCP particle size.