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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:26 |
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Conference: Bucharest University Faculty of Physics 2001 Meeting
Section: Optics and Spectroscopy
Title:
BIOCOMPATIBLE CALCIUM PHOSPHATE THIN FILMS GROWN BY PULSED LASER DEPOSITION
Authors:
Valentin Nelea, Ion N. Mihailescu, Valentin Craciun,
Gheorghe Marin, Alexandru Hening, Monica Iliescu
Affiliation:
INFLPR, Sectia Laseri, P.O. Box MG-36, 76900, Bucuresti, Magurele
E-mail
Keywords:
Abstract:
In the biomaterials field research, calcium phosphate materials are the best choice in the manufacturing of the prosthetis devices used for bone repair and replacement. Among them, hydroxyapatite is resorbed the least by the physiologic media, being the main constituent of bone tissue. However as ceramic bulk hydroxyapatite is fragile and it can not be used directly in bone reconstruction. In form of thin film, the mechanical characteristics (especially the adherence at the surface prosthesis) strongly enhance. In this work we present a method for growth of bidimensional hydroxyapatite structures using the pulsed laser deposition technique. The films were grown from ceramic hydroxyapatite targets in vacuum (10-5 torr) or in low pressures oxygen (10-2 – 10-1 torr) on Ti-5Al-2.5Fe and Si substrates heated at temperatures within the range 20-650°C. We used an KrF* excimer laser source (248 nm wavelength and 20 ns laser pulse duration). After deposition some of films were 1 hour annealed in ambiant air at 550°C. Others films were submitted during deposition to the action of UV radiation of a halogen lamp (172 nm wavelength). The deposited structures were morfologically, structurally and mechanically characterized by (confocal) optical microscopy, electronic microscopy, X-ray diffraction (Bragg-Brentanno and grazing incidence modes) and static and dynamic nanoindentation. Our studies have evidenced a strong competition between the deposition conditions and the features of the films in fonction of the proccessing specificity. Generally, the films are adherent and crystalline. The films assisted during growth by the UV radiation were smoother and present better mechanical properties. However we observe a partial decomposition of the hydroxyapatite phase.
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