Complex Dielectric Permittivity of Metal-Containing Nanocomposites: Non-phenomenological Description

Addition of metal nanoparticles radically alters the complex dielectric permittivity of a matrix-insulator. A non-phenomenological theory describing these changes is developed by assuming that a large concentration of electron traps with the critical binding energy in the amorphous matrix exists. Such traps in the vicinity of the nanoparticles can be partially occupied by the electrons. The trapped electron with its neighbor nanoparticle then represents an appreciable dipole moment. Reorientations of this moment in the external electric field occurs due to electron jumps between the traps over a sphere surrounding a nanoparticle. The calculation of the interaction of the dipole moment with an external field is carried out taking into account the dielectric permittivity of the matrix. By deriving and solving the equation for the dipole relaxation function, the real and imaginary parts of the permittivity may be evaluated. The calculated dependences of the dielectric permittivity on frequency and temperature agree qualitatively with experiment.