Phase transformation and structural characteristics of zinc-incorporated β-tricalcium phosphate

Biological performance of bioceramics such as calcium phosphate has been proved to be improved by substitution of different ions like Mg, Sr and Si. In this study, different amounts of Zn ions in nitrate form were incorporated into β-tricalcium phosphate in which various molar ratios of Ca:Zn were achieved: 3:0, 2.8:0.2, 2.6:0.4, 2.4:0.6, and 2.2:0.8. The mixtures were heated at different temperatures ranging from 800–1100 °C. The phase composition, amount of each phase and lattice parameters of β-tricalcium phosphate were determined by means of X-ray diffractometry and coupled software. Also, solubility of the heated mixtures was investigated by determining the amount of Ca and Zn released into a simulated body fluid during 120 h. The results revealed that only limited amount of Zn ions could be incorporated into β-tricalcium phosphate lattice and ZnO phase was formed when high content of zinc nitrate was introduced in initial mixture. Both a and c lattice parameters of β-tricalcium phosphate were reduced by adding Zn. The release rate of calcium ions into the simulated body fluid was approximately constant during 120 h while for Zn minor release was observed.