  Dyonic black hole solutions with spherically symmetric configurations within
general relativity are investigated where the source of the gravitational field
is Born - Infeld-type electrodynamics. Corrections to Coulomb's law and
Reissner - Nordstrom solutions are obtained. From principles of causality and
unitarity we find the restriction on electric and magnetic fields. The Hawking
temperature and the heat capacity of black holes are obtained. At some event
horizons second-order phase transitions take place.
