RF magnetron-sputtered coatings deposited from biphasic calcium phosphate targets for biomedical implant applications

•Targets with homogeneous mixtures of tricalcium phosphate and hydroxyapatite were used to deposit quasi-amorphous coatings.•Deposited coatings can be transformed to a crystalline state using annealing in air at 700 °С for one hour.•The structure, composition and morphology of the coating can be controlled by the composition of the biphasic target.•The addition of tricalcium phosphate to the biphasic mixture led to a finer size of the surface structural elements.

Bioactive calcium phosphate coatings were deposited by radio-frequency magnetron sputtering from biphasic targets of hydroxyapatite and tricalcium phosphate, sintered at different mass % ratios. According to Raman scattering and X-ray diffraction data, the deposited hydroxyapatite coatings have a disordered structure. High-temperature treatment of the coatings in air leads to a transformation of the quasi-amorphous structure into a crystalline one. A correlation has been observed between the increase in the Ca content in the coatings and a subsequent decrease in Ca in the biphasic targets after a series of deposition processes. It was proposed that the addition of tricalcium phosphate to the targets would led to a finer coating's surface topography with the average size of 78 nm for the structural elements.

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