β→α Transformation in tin as studied by electrical resistance and optical reflectance under vacuum and at high pressure

Principal Ideas of Crystal Growth

“…It is important that while the ß-+ u transformation is very sluggish and requires either very long time periods (days to years) or signifieant supereoolings and /or seeding with n-crystallites, the reverse transformation (u -+ ß) oeeurs rapidly as soon as the temperature exeeeds the equilibrium value, as is inherent in the diffusionless meehanismY93. 194) Other examples of polymorphie transitions are graph ite-diamond transformation in earbon, FCC-BCC transformation in iron, and sphalerite-wurtzite transformation in zine sulfide and some other eompound semieonduetors. In a sense, transitions between polytype struetures ean also be eonsidered as aversion of the polymorphism phenomena.…”