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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:20 |
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Conference: Bucharest University Faculty of Physics 2011 Meeting
Section: Solid State Physics and Materials Science
Title:
Nanostructured hydroxyapattite for biomedical applications – synthesis and characterization
Authors:
O. Florea (1,2), Daniela Predoi (2), A. Costescu (1,2), C. Berbecaru (2)
Affiliation:
1) National Institute for Physics of Materials, P.O. Box MG 07, Bucharest, Magurele, Romania.
2)Faculty of Physics, University of Bucharest, Romania.
E-mail
florea.ovidiu.gabriel@gmail.com, dpredoi68@gmail.com, adrian.costescu@gmail.com, berbecaru2ciceron@yahoo.com
Keywords:
nano-hydroxyapatite, sol-gel method, dielectric measurements
Abstract:
Nanotechnology has been applied in the field of biomaterials to improve the biological responses of the synthetic hydroxyapatite (HAp) which is more close to mineral nano-grade HAp in bones. Nano-HAp exhibits certain superiority in the field of orthopedic implants in the osteogenesis process for its improved biological and biomechanical properties.Nano-hydroxyapatite bio-ceramics were synthesized by sol-gel method. The gel was dried at 80 oC for 96 h. The dried gels were individually heated at a rate of 5 oC/min up to 600 oC, 800 oC, and 1000 oC. X –ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), thermogravimetric measurements (TG and DTG) and Fourier Transform Infrared Spectroscopy (FTIR) were used to investigate the structure, morphology, particle size and composition of the samples. At 800 oC a small amount of CaO (about 0.3 wt %) was detected which increased after annealing at 1000 oC (about 1.1 wt %). The crystallites are elongated in the c direction of the crystallographic axis, and the size anisotropy decreases with increasing temperature above 800 oC. The size along the elongation axis increased from 43 nm at 80 oC to about 143 nm at 1000 oC, as determined by XRD, and from 120 to 280 nm, as measured by TEM. FTIR measurements show the characteristic peaks for crystallized hydroxyapatite. Dielectric measurements were performed on an extended temperature (25 - 700 oC) and frequency ranges (72 Hz - 5 MHz). Samples obtained at 80 oC show no reproducible permittivity and loss values on heating or cooling in the 25 - 250 oC temperature range due to the physically and chemically bonded water. More stable and reproducible permittivity and loss values were recorded for the samples treated at 1000 oC. Also the permittivity and loss decrease their values with the frequencies increase.
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