Liquid Phase Separation and Precipitation of (alpha)-AgI Nano-Crystallites from AgI-Ag2O-B2O3 Melt

The dc electrical conductivity, (sigma)dc, was measured for liquid (AgI)x-(Ag2O)y-(B2O3)1-(x+y) (x=0.7-0.9; y=0.05-0.2) by using an ac impedance method in particular concern with the precipitation mechanism in the (alpha)-AgI precipitated glass, which was prepared by a rapid quenching technique due to a twin-roller apparatus. The temperature dependence of (sigma)dc exhibits two inflexion points. The existence of two liquid phase separation was confirmed by the electrical conductivity measurements with the use of specially designed cell. In addition, the X-ray diffraction and the SEM (Scanning Electron Microscope) experiments were performed for the rapidly quenched samples. The (alpha)-AgI precipitated glass was obtained by adopting the higher holding temperature even for the composition for which the (beta)-AgI precipitated glass was prepared in the case of a lower holding one. These results indicate the role of two liquid phase separation on the preparation process of nano (beta)-AgI crystallites in the glass matrix.