Effect of processing parameters on the properties of hydroxylapatite films grown by pulsed laser deposition

Abstract

Thin films of hydroxylapatite (HA) (Ca 10(PO 4) 6(OH) 2) were created on Ti substrates by KrF laser ablation. The layers were deposited in vacuum, in pure H 2O vapours (pressure, 2 × 10 −3 to 2 × 10 −1 mbar) and in an Ar-H 2O vapour mixture. The influence of the laser energy density E T (3 J cm −2, 13 J cm −2) and substrate temperature T s (500–760 °C) on the film parameters was studied. Two different processes were used for HA target preparation. Films and targets were characterized by Rutherford backscattering (RBS) analysis, particle induced X-ray emission (PIXE), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Knoop microhardness and scratch tests. For lower T s 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-H 2O vapours. Time of flight (TOF) spectra of the plasma plume from the HA target were also analysed.