Structure and Biocompatibility Analysis of Sol-Gel Prepared Niobium and Titanium Oxide with Temperature

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New York State College of Ceramics at Alfred University. Kazuo Inamori School of Engineering.
Niobium and titanium oxides were prepared via the sol-gel technique. The structural evolution of these oxides with calcination temperature (150-650oC) was investigated using differential thermal analysis (DTA), high temperature x-ray diffraction (HTXRD), and Raman spectroscopy. The phase transformations of the niobium oxide as a function of calcination temperature were as follows; amorphous to hexagonal (~500oC) and hexagonal to orthorhombic (~600oC). The crystallite size increased from 23 to 74 nm. The titanium oxide remained amorphous to 325oC until crystallization to the tetragonal anatase phase at ~350oC, and remained so until 650oC. The anatase crystallite size increased from 22 to 45 nm. The lattice parameters and cell volumes for both niobium and titanium oxides were determined using the Rietveld method from which the linear and volume thermal expansion coefficients were calculated respectively. Raman spectroscopy was used to further characterize the structure of these oxides and both band position and shape were strongly dependent on calcination temperature, with overall results consistent with HTXRD. A series of selected oxide compositions and structures including; TiO2-amorphous (275oC), TiO2-tetragonal (500oC), Nb2O5-amorphous (450oC), Nb2O5-hexagonal (525oC), and Nb2O5-orthorhombic (650oC), were then selected for bioactivity testing using simulated body fluid (SBF) analysis. Bioactivity was determined through the analysis of calcium phosphate formation at the surface of selected oxides as a function of SBF reaction time, as observed under Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). It was shown that bioactivity was a function of crystallinity, as TiO2-tetragonal (500oC), and Nb2O5-hexagonal (525oC) were the only oxides which exhibited bioactivity.
Advisory committee members: Matthew Hall, Scott Misture. Dissertation completed in partial fulfillment of the requirements for the degree of Masters of Science in Materials Science and Engineering at the Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University