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SBF studies of Bioglass Nanostructured Thin Films obtained by pulsed laser deposition or magnetron sputtering: a comparative study |
Ciceron A. Berbecaru 1, Horia V. Alexandru 1, Constantin Morosanu 2, Adrian Slav 2, George Stan 2, Dan Marcov 2, Adelina Ianculescu 3, Andrei Popescu 4, Gabriel Socol 4, Felix Sima 4, Ion Mihailescu 4 |
1. University of Bucharest, Faculty of Physics, Bucharest-Magurele p.o.box mg-11, Bucharest 76900, Romania |
Abstract |
Nanostructured thin films have been obtained by pulsed laser deposition (PLD) [1,2] and magnetron sputtering (MS) methods from bioglass (BG) targets. Three types of powders with different silica content (54,57 or 61 %) were selected for these experiments. Titanium alloys, silicon and quartz were used as substrates for micronic thin films deposition. PLD films resulted partially crystallized as an effect of substrate heating at 400 deg C during deposition. MS layers showed a prevalent amorphous structure, even after post annealing at 750 deg C in air. Quite unexpectedly, MS films displayed “droplets” structured at a nano-micro level, as evidenced by SEM analyses. PLD films displayed typical nanoparticulates present either on surface or embedded inside obtained nanostructures. The stoichiometry of the targets was conserved in case of PLD films but largely modified for MS depositions (namely an increase of P/Si ratio was observed). The behavior in SBF solutions of all obtained structures was tested in dedicated chemical growth experiments. The samples were kept in SBF for 1,3,7,14, or 21 days then extracted and investigated by FTIR, SEM and XRD in comparison with pre-immersion evidence. The observed chemical evolutions could be assigned to dissolution and precipitation processes at solid liquid interface due to an ionic exchange between BG and SBF. This mechanism is quite similar to that observed in the case of SBF in-growth onto crystalline and amorphous hydroxyapatite sputtered films [3]. In view of increasing adhesion to substrates, functional graded compositional structures have been also prepared by magnetron co-sputtering, using titanium and bioglass targets. The method efficiency was demonstrated by “pull off” studies of deposited layers. References: [1] E. Gyorgy, et all, to appear in: Appl. Surf. Sci. (doi:10.1016/j.apsusc.2007.02.146); [2] D. Tanaskovic, et all, accepted at E-MRS’07, Spring Meeting; [3] Liliana Verestiuc et all, J Cryst. Growth 264 (2004) 483 |
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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium J, by Ciceron A. BerbecaruSee On-line Journal of E-MRS Fall Meeting 2007 Submitted: 2007-05-14 17:44 Revised: 2009-06-07 00:44 |