Dilatometric Study of the Crystallization Behavior of Pure and Doped Selenium

The crystallization behavior of pure vitreous selenium and selenium doped with various concentrations of arsenic, chlorine, bromine, and iodine was investigated by a dilatometric method, with particular emphasis on constancy of the thermal pretreatment of samples. The energy of activation for the crystallization of vitreous selenium was found to be 25 kcal/mole. Arsenic had a very pronounced retarding effect at the 100 ppm level. Chlorine and iodine showed a complex behavior, whereas bromine showed a moderate accelerating effect on the rate of crystallization of selenium.