EFFECT OF PROCESSING PARAMETERS ON THE PROPERTIES OF HYDROXYLAPATITE FILMS GROWN BY PULSED-LASER DEPOSITION

Thin films of hydroxylapatite (HA) (Ca-10(PO4)(6)(OH)(2)) were created on Ti substrates by KrF laser ablation. The layers were deposited in vacuum, in pure H2O vapours (pressure, 2 x 10(-3) to 2 x 10(-1) mbar) and in an Ar-H2O vapour mixture. The influence of the laser energy density E(T)(3 J cm(-2), 13 J cm(-2)) and substrate temperature T-5 (500-760 degrees C) on the film parameters was studied. Two different processes were used for HA target preparation. Films and targets were characterized by Rutherford backscattering (RES) analysis, particle induced X-ray emission (PIXE), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Knoop microhardness and scratch tests. For lower T-5 and higher E(T), the Ca/P ratio in the films was similar to that in the HA target. Crystalline HA peaks were found preferentially in the films deposited in the presence of Ar-H2O vapours. Time of flight (TOF) spectra of the plasma plume from the HA target were also analysed.