The reasons for the anomalously rapid (for solids) growth of ''cancers
'' (filamentary crystals, hills, pores, and other formations) on the s
urface of samples of superionic conductors with mixed electronic-ionic
conductivity (of the type Cu2-xSe and Ag2Te) are discussed. The effec
ts are attributed to the acceleration of mobile ions and activated ion
s in the ''core'' of the superionic by free electrons in the joint ''c
hemical'' diffusion of ions and electrons in the samples. (C) 1996 Ame
rican Institute of Physics.