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The densities of liquid Bi, Sn, Pb and Sb have been precisely measured from the melting point up to about 1100 K using an improved Archimedean method. The densities at the melting point for liquid Bi, Sn, Pb and Sb are 10.042 × 103, 6.983 × 103, 10.635 × 103 and 6.454 × 103 kg m−3, respectively. Comparisons between our data and those from the literature have been made and they show the present results to be more reliable. Rather than a linear fit for the temperature dependence of the density, a slight deviation from linearity in the temperature dependence of the densities has been observed.

In situ observation of tin whisker growth in NdSn3 compound was carried out by using an optical microscope (OM) and scanning electron microscopy (SEM). The growth rate of Sn-whisker from NdSn3 is shown to be rapid (approximately 8-15Å/s) during exposure to room ambience, and it is accompanied by formation of a new compound, Nd(OH)3, as was confirmed by x-ray diffraction. This reaction between the Sn-RE compound and trace water in room ambience has significant influence on whisker growth. There is an electron irradiation effect on whisker growth; that is, whiskers stopped growing after being observed in SEM. Therefore, it is suggested that OM be used rather than SEM to observe the continuous whisker growth. In discussion, the driving force per Sn atom for whisker growth is estimated as 1 × 1014 N in accordance with the whisker growth rate, and its apparent force originates from a chemical potential gradient between the released Sn atoms and the whisker.

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