University of Jyväskylä

Dissertation: Ca-O-P thin film preparation, modification and characterisation (Arcot Rajashekar)

Start date: Dec 16, 2011 12:00 PM

End date: Dec 16, 2011 03:00 PM

Location: Mattilanniemi, FYS1

AnandaM.Sc. Ananda Sagari Arcot Rajashekar defends her doctoral dissertation titled  “Ca-O-P thin film preparation, modification and characterisation”. Opponent John E.E. Baglin (IBM Almaden Research Center) and custos Adjunct Professor Timo Sajavaara (University of Jyväskylä).

Abstract

Bioceramics are biocompatible ceramic materials, which interact with biological systems of the body to treat, strengthen or replace body functions. Among most conventional bioceramics, hydroxypaptite belonging to the group of calcium phosphate ceramics is one of the most commonly used. One approach to prepare synthetic hydroxyapatite is to first deposit amorphous Ca-P-O thin film and then by means of post deposition annealing initiates the formation of hydroxyapatite crystals to the film.

In this study Ca-P-O films were deposited by using ion sputtering and atomic layer deposition. The Ca/P atomic ratios of as-deposited amorphous films were determined by means of ion beam analysis. Ca/P for sputtered films using hydroxyapatite target with excess phosphorous, approached stoichiometric hydroxyapatite. Though the sputtered films showed good biocompatibility in cell attachment studies, the dissolution of as-deposited films in cell culture medium is a disadvantage.  In order to determine effect of surface properties of thin films, Ca-P-O films were deposited on Si, rough and smooth Ti metal substrate using atomic layer deposition. Ti was selected in order to combine the biocompatibility of Ca-P-O thin films with mechanical strength of the Ti metal substrate. Ca/P ratio similar to that of hydroxyapatite for obtained for thin films on Ti substrate with smoother surface than on rough substrate. Post deposition annealing of Ca-P-O films on Si substrate showed filopodic morphology of pre-osteoblast cells. Similar effect was observed on annealed films on Ti substrate but higher temperature annealing substantially dropped number of due to the formation or rutile phase on the surface.

Further information:

Ananda Sagari Arcot Rajashekar, tel. 045 203 9996, ananda.s.arcot-rajashekar@jyu.fi

The dissertation is published in the series JYFL Research Report 12/2011, ISBN: 978-951-39-4585-5, 978-951-39-4586-2 (pdf), ISSN: 0075-465X. Inquiries: Ananda Sagari Arcot Rajashekar or the Department of Physics, tel. 040 805 4120.


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