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

Abstract

Composite particles consisting of aragonite and hydroxy-carbonate apatite (HCA) were developed using strontium-containing aragonite [(Ca,Sr)CO₃] as the precursor via a phosphate-solution reaction under controlled conditions. An HCA layer with an approximate thickness of 1 µm was uniformly formed on the surfaces of the (Ca,Sr)CO₃ particles. The formation of this HCA layer was achieved using (Ca,Sr)CO₃; 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 Ca²⁺ and Sr²⁺ 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.