Freezing and Melting of Mercury in Porous Glass

Results of the investigation of the liquid-solid phase transition in ultra dispersive mercury which was obtained by filling porous glass with metallic mercury are described. The neutron diffraction measurements were performed on the DN-2 TOF diffractometer at the IBR-2 reactor. At room temperature no diffraction peaks are observed. In the cooling mode solidification starts at 205 K and leads to the appearance of Bragg peaks. In the measured spectra the intensity of the peaks is increasing with a decrease in the temperature which probably indicated an increase in the concentration of the solid phase. At t < 100 K the saturation of the I(T) dependence was observed. The low temperature diffraction pattern coincides exactly with the diffraction pattern of bulk mercury, but all the peaks are broader. Measurements in the heating mode reveal an extremely large hysteresis in the I(T) dependence. We would like to note that the results of neutron experiments correspond exactly with the results of specific heat measurements with the same sample. 7 refs., 3 figs