EFFECTS OF SINTERING CONDITIONS ON HYDROXYAPATITE FOR USE IN MEDICAL APPLICATIONS - A POWDER DIFFRACTION STUDY

Commercially available hydroxyapatite (HA) has been subjected to different temperatures and sintering-time schedules to examine the effects of these two variables on crystal structure. Small but significant decreases in unit-cell volume and hydroxy-ion channel size are seen on sintering for 1 h at temperatures in excess of 1000-degrees-C. This has been ascribed to the loss of small amounts of carbonate from the channels within the structure. The stability of the HA phase was seen up to a sintering temperature of 1400-degrees-C, with decomposition only seen in the 1450-degrees-C sinter. Extended sintering times at 1300-degrees-C failed to cause decomposition; however, small increases in c-axis length and unit-cell volume were observed.