Formation of hydroxy-carbonate apatite on the surfaces of strontium-containing aragonite

Composite particles consisting of aragonite and hydroxy-carbonate apatite (HCA) were developed using strontiumcontaining aragonite ((Ca, Sr)CO 3 ) as the precursor via a phosphate-solution reaction under controlled conditions.An HCA layer with an approximate thickness of 1 m was uniformly formed on the surfaces of the (Ca, Sr)CO 3 particles.The formation of this HCA layer was achieved using (Ca, Sr)CO 3 ; the introduction of Sr into aragonite, along with the adjustment of the phosphate solution's pH and temperature, contributed to the moderate dissolution of aragonite.The gradual release of Ca 2+ and Sr 2+ ions from the particles, followed by their rapid reaction with phosphate ions in the solution, resulted in the formation of HCA on the particle surfaces.