Optical properties of bismuth granules in a glass matrix

Optical absorption characteristics for ultra-fine bismuth particles having dimensions around 10 nm and dispersed in both silicate and vanadium phosphate glass matrices have been investigated in the wavelength range 300 to 700 nm. Bismuth particles in vanadium phosphate matrix show an absorption peak around 440 nm whereas in silicate glass matrix they give two peaks in the ranges 500 to 530 nm and 420 to 430 nm respectively. The peak positions in all the glass-bismuth metal systems are predicted in fair agreement with experiment by Maxwell-Garnett (mg), as extended by Polder and van Santen (mg-pvs) and Bruggeman (br) effective medium theories. It is observed, however, thatmg-pvs andbr models give the best fit to experimental data over the entire wavelength range studied.