Equilibrium charge of small metal particles and hopping transport in a metal-insulator composite

It is shown that the thermodynamically equilibrium state of a system of sma ll metal particles placed in a dielectric matrix are unavoidably charged. T he charge of spherical metal particles with different radii is calculated a t low temperatures. Hopping transport in a system of metal particles is stu died. It is shown that it is limited by the charging energy, which serves a s a typical hopping energy and can be gapless. (C) 1999 American Institute of Physics. [S0021-3640(99)00620-9].