Formation And Growth Of Cuprous Halide Nanocrystals In A Viscoelastic Matric By High Temperature Spectroscopy

The object of the paper is the formation and the growth of cuprous halide nanocrystals (CuClxBr1-x=o...1) in a glass matrix studied by UV vis spectroscopy in the temperature range between 25 and 650 degrees C. The influence of [Cl]:[Br] ratio, [Cd2+], and [Sn2+] (essential components for photochromic behaviour) on formation and growth of CuClxBr1-x nanophases was also investigated. It was found that the formation rate of the CuClxBr1-x nanophases in the glass matrix apparently is decreased with increasing [Cl] at a given temperature (above Tg). Treating the glass matrix as a viscoelastic media, this behaviour is discussed and interpreted. The incorporation of Cd2+ into the CuClxBr1-x nanophase during formation and growth depends on heat treatment time. The longer the treatment time the higher is the resulting [Cd2+] of the nanophases. The total concentration of Cd2+ influences the solubility of CuClxBr1-x, especially if the [Cl] is high. No influence of Sn2+ on solubility and preparation of CuClxBr1-x nanophases was found, but redox state of copper ions is controlled by [Sn2+]. Finally the hysteresis of melting and freezing behaviour of the CuClxBr1-x nanocrystals as a functuon of size and composition is discussed.