ISSN:
1662-8985
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
An evolution of the structure of three glasses of Na2O-Nb2O5-SiO2 system in the courseof isothermal heat treatments at 660–700°C and the extinction coefficient of the material werestudied. Spinodal phase separation was found to be a primary process followed by precipitation ofnano-sized NaNbO3 crystalline phase. It was found that the spectral dependence of the extinctioncoefficient in the wavelength range λ= 400–800 nm corresponds to light scattering by spinodalstructure at the phase separation stage and by independent Rayleigh scatterers (NaNbO3nanocrystals) at the early stage of crystallization. The extinction coefficient increases at the first halfof the crystallization stage and then decreases. At the late stage of crystallization and for the finalglass-ceramics, the extinction coefficient α is 10–20 times smaller than that calculated forindependently scattering nanocrystals and is characterized by anomalous wavelength dependence(α ∝ λ−6). The model for calculation of extinction coefficient is proposed, in which the interferenceeffects in light scattering by nanocrystals are taken into account. On this basis, the variation ofextinction coefficient in the course of crystallization and its wavelength dependence are explained
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.39-40.273.pdf
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