Microwave annealing for preparation of crystalline hydroxyapatite thin films
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A sol was spun on single crystal silicon substrates at a spin-rate of 3000–5000 rpm followed by a low temperature cure to form a stable sol–gel/silicon structure. Good quality crystalline HA films of thickness ∼300–400 nm were obtained by annealing the sol–gel/Si structure in a conventional cavity applicator microwave system with a magnetron power of 1300 W, frequency of 2.45 GHz, and at a low processing temperature of 425 °C for annealing times ranging from 2–60 min. X-ray Diffraction and FTIR analysis confirmed that the crystalline quality of the thin films were comparable or better than those heat-treated under the same processing conditions (temperature and time) in a Rapid Thermal Annealing (RTA) system. The RBS data suggests a composition corresponding to stoichiometric hydroxyapatite Ca10(PO4)6(OH)2, the major inorganic component of bone. The results showed that the HA film thickness decreases with increasing sol spin-rate. The HA films showed good biocompatibility because little monocyte adhesion occurred and hence no inflammatory response was activated in vitro. The potential of microwave annealing for rapid and low temperature processing of good crystalline quality HA thin films derived from sol–gel is demonstrated.
KeywordsRapid Thermal Annealing Rutherford Backscattering Spectrometry Monocyte Adhesion Splitting Factor Rutherford Backscattering Spectrometry Spectrum
The authors would like to acknowledge the financial support of the National Research Foundation (South Africa)—Grant numbers: 2053829 (EGIC) and 2050587 (URDP), University of the Western Cape and Arizona State University (ASU). The work is partially supported by the NSF (USA), to whom the authors are greatly indebted. A word of thanks is also due to Shawn Whaley (Department of Chemistry, ASU) for the assistance with the FTIR analysis. We gratefully acknowledge the use of facilities within the Center for Solid State Science at ASU.
- 5.Sutton WH (1989) Ceram Bull 68(2):76Google Scholar
- 11.Lopatin CM (1999) PhD Thesis, Arizona State UniversityGoogle Scholar
- 12.Powder diffraction File, Joint Committee on Powder Diffraction Standards (JCPDS), Card No. 9-432, 1994Google Scholar
- 13.Cullity BD (1967) Elements of X-ray diffraction. Addison Wesley, Read, MA, p 99Google Scholar
- 19.Bornside DE, Macosko CW, Scriven LE (1987) J Imaging Tech 13:122–129Google Scholar
- 20.Brinker CJ, Scherer GW (1990) Sol–gel science Academic Press, Boston, MAGoogle Scholar
- 28.Van Wazer R 1958 Phosphorous and its compounds. Interscience Publishers, Inc, NY, p 515Google Scholar
- 30.Smith RD (2004) Masters Thesis. Arizona State UniversityGoogle Scholar