Effect of H2O on Cu incorporation and deposition behaviors in hydroxyapatite by heat treatment

Abstract

The effect of H2O in the atmosphere during heat treatment on Cu incorporation/deposition into hydroxyapatite was investigated after loading a Cu aqueous solution. Cu-incorporated apatite, Ca10(PO4)6Cux(O,OH)2 (Cux-Ca-HAp), was successfully synthesized from single-phase apatite under an atmosphere of low H2O concentration. The deposition of Cu from the apatite channel was facilitated under a H2O atmosphere at high temperatures. CuO deposition from Cu0.5-Ca-HAp under heat treatment in 10% H2O-air occurred at a lower temperature (600 °C) than that required when heating in dry air. The same deposition temperature is required when heat treatment in 10% H2O–N2 is used, indicating that the O2 concentration in the atmosphere is less conducive to the deposition of CuO than H2O vapor. In addition, we successfully synthesized single-phase apatite with a relatively high Cu content, up to 1.38 per apatite unit cell, by heat treatment under a dry N2 atmosphere.