New hydroxyapatite–hydrotalcite composites I. synthesis

The synthesis and characterization of original materials, composed by hydrotalcite and hydroxyapatite, is discussed. All the syntheses were carried out in presence of microwave irradiation during the crystallization step. The interactions between the two compounds depend on the synthesis procedure. If hydroxyapatite is incorporated to hydrotalcite, the first compound is encapsulated by hydrotalcite. Instead, if hydroxyapatite is first prepared, the resulting solid is essentially a hydrotalcite with interlayered hydroxyapatite. When the composite material is synthesized by a simultaneous coprecipitation, the small clusters of hydroxyapatite and hydrotalcite are homogeneously dispersed. Consequently, the specific surface area and the particle size vary.