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RESEARCH PRODUCT

Evolution of the structural and optical properties from cobalt cordierite glass to glass-ceramic based on spinel crystalline phase materials

subject

description

Co 2+ -containing cordierite stoichiometric glasses have been prepared by melting colloidal gel precursors. After controlled thermal processing in the range of temperatures between 900 and 1300 C different polycrystalline, almost single phase materials displaying l-, a-, and b-cordierite crystalline forms were synthesized. In addition, spinel glass-ceramic materials were also prepared from the base glasses. All these materials were characterized by X-ray powder diffraction and infrared spectroscopy. Room temperature (RT) absorption and emission spectra of Co 2+ – cordierites and – spinel-glass material have allowed determining the local environment of the Co 2+ in the crystalline structure of final materials. Results indicated that whereas in parent glasses and in the l-cordierite forms there are a large fraction of Co 2+ in octahedral coordination, in the low (b-) and high (a-) temperature crystalline forms the proportion of Co 2+ in tetrahedral coordination increased. The final CoAl2O4-glass composite showed absorption and emission spectra very similar to the sol–gel CoAl2O4 spinel, both displaying pure Co 2+ tetrahedral coordination.