The transformation of tin from it’s metallic state into a powdered state is increasing important due to the use of lead-free solders, which are almost pure tin.
The transformation involves two naturally occurring forms (allotropes) of tin, the semi-conducting powder form is labeled the alpha-tin and the metallic form is a beta-tin. The transformation usually occurs at low temperatures, it’s auto-catalytic, and has been observed in church organs in cold northern European countries and the buttons of Napoleon’s army when invading Russia. The auto-catalytic nature of the transformation lead to the name ‘tin pest’ because the reaction looks to eat into the metal.
The reaction can usually take several months but Davide Di Maio and Chris Hunt at the National Physics Laboratory, accelerated the transformation by seeding the tin with a cadmium-telluride powder. Cadmium-telluride has the same (diamond cubic) crystal structure as the powdered form and can therefore act to nucleate alpha-tin from the (tetragonal structured) metal.
The results of the acceleration were captured using time lapse photography in a microscope.
There results are published Time-lapse photography of the β-Sn/α-Sn allotropic transformation in the Journal of Materials Science: Materials in Electronics, doi: 10.1007/s10854-008-9739-5. Seems to currently be published ‘online first’.