Abstract
Fine mercury whiskers have been grown from the vapour on a cold glass substrate. These whiskers attained a length of about 1 mm. Electron microscopy revealed that this type of crystal has a square cross section bounded by the {011} and {110} planes. Mercury platelets were also grown from the vapour by a similar method. Optical microscopy showed that these platelets have two different shapes: rhombus and parallelogram shaped crystals were observed. Electron microscopy showed that the rhombus shaped crystals have a lateral face parallel to the {111} plane, which is the closest packed plane in mercury; the parallelogram shaped crystals were found to have a lateral face parallel to the {011} plane in mercury. The as-grown platelets were found to be too thick for transmission electron microscopy, so they had to be deformed in order to reduce their thickness. The deformed crystals revealed some very interesting features from which valuable information on the defects structure in mercury was obtained. The thickness of the deformed crystals was measured and errors have been found in previously published investigations. Stacking faults in solidified mercury were observed and found to lie on the closest packed plane having either the [011] direction or the [110] direction. The slip mode of crystalline mercury near its melting point was studied by the observation of traces in the foils, the slip elements were found to be {111} and {111} . Dislocation networks have been observed and the investigations carried out suggest that the dislocation interaction could represent the following type of reaction; 1/2 [110] + 1/2 [101] → 1/2 [011] It was not possible to have a thin enough crystal with a lateral face parallel to the (110) plane even after deformation and this indicated that the parallelogram shaped specimens were thicker than the rhomboid specimens. All the diffraction patterns obtained from them showed distinctive streaks coming from stacking faults lying on the {111} plane which is perpendicular on the {110} plane. Errors have been found in published tables of interplanar spacings for the mercury lattice and corrected values are included in table 2.1 and discussed in Appendix I. Electron microscopy of crystalline ethyl alcohol showed that its structure is consistent with the face-centred cubic structure, with a lattice parameter of 3.29 +/- 0.02 A.