Hydroxyapatite layers prepared by sol–gel assisted electrostatic spray deposition

Hydroxyapatite (HAP) thin films were prepared by the sol–gel assisted electrostatic spray deposition (ESD) using calcium nitrate and phosphoric acid as starting materials. Methanol was used as solvent in the precursor solution. Final annealing was done at 500 °C for 30 min in air. Crystallinity, chemical structure, and surface morphology of the films were analyzed. Well-crystallized hydroxyapatite films were obtained by final annealing at 500 °C. Eighty degree celsius was the ideal substrate temperature for preparing smooth and dense hydroxyapatite films.