Undercooling of Liquid Bismuth and Formation of Bismuth-Ⅱ at Normal Pressure

This paper studied the undercooling of liquid bismuth and the formation possibility of bismuth-Ⅱ phase at normal pressure by using a high clean and containerless environment provided by a five meters long drop-tube and an alternate approach to heat and cool the molten bismuth in helium atmosphere. The two methods have allowed the ability of undercooling for liquid bismuth to be extended through controlling of the droplet size and cooling rate. The result of X-ray diffraction indicated that the undercooling samples have a monoclinic lattice with the lattice parameters a=0.696 8 nm, b=0.628 6 nm, c=0.339 7 nm and =110.33. To make a comparison between the volume of unite cell and that of the bismuth-Ⅱ (monoclinic lattice) obtained by Brugger at 2.6 GPa, the latter has a compression of 9.34% relative to the former, the result is in good agreement with Bridgman's.