Effect of Laser Fluence on Poly-crystallization of Hydroxyapatite Film Coated by PLD Method

We successfully obtaineed the poly-crystallized coatings of the bioactive hydroxyapatite (HAp) on the titanium plates at room temperature. We used several ceramics HAp targets prepared by sintering at different temperature of 500 o C, 700 o C, 900 o C and 1100 o C. These targets were ablated by the KrF excimer laser with fluence of 4J/cm 2 , 5J/cm 2 and 6J/cm 2 . The film depositions were performed under 1 Torr H 2 O atmosphere. The amount of HAp polycrystals increased as the laser fluence rised. The film deposited from a target sintered at 900 o C included a much amount of the crystalline of HAp. We concluded that the ablated species had different energies depending on both the target density and the laser fluence. It resulted in the difference of migration and crystallization of the HAp film.