GROWTH AND OPTICAL-PROPERTIES OF BI12SIO20 SINGLE - CRYSTALS DOPED WITH FIRST ROW TRANSITION-METAL AND ALUMINUM

Bi12SiO20 single crystals co-doped with first row transition metals an d aluminum were grown from the melt by the Czochralski technique. Opti mal growth conditions for optically homogeneous crystals have been est ablished. Dopant molar concentrations in the crystal were determined a nd segregation coefficients calculated. Transmission spectra were meas ured in the 0.38-0.85 mu m range. It was established that adding Al to the melt bleached the crystals and blue-shifted the entire transmissi on spectrum. Doping with Cu produced a strong photochromic effect afte r daylight exposure, changing the crystal color from yellow to red.