Growth of silver nanowires using mica structure as a template and ultrahigh dielectric permittivity of the nanocomposite

Abstract

Fluorphlogopite mica crystallites of dimensions in the range 0.5 to 24 μm were grown within silicate glass of suitable compositions by heat treatment at 1168 K. After an ion exchange treatment (K⁺ ⇆ Ag⁺) the specimens were subjected to an electrodeposition reaction. With the optimum concentration of K⁺ ions in the precursor glass, electrodeposition brought about the growth of silver nanowires about 0.5 nm diameter within the nanochannels of the fluorphlogopite mica structure. By applying a voltage pulse of 20 volts of duration 3 s, break junctions could be induced in the nanowires. A high dielectric constant of around 1.0 × 10⁷ was found in the resultant specimen. This was shown to be quantum mechanical in origin and arose due to the presence of metal filaments about 1280 nm in length. An asymmetric voltage-current characteristic was recorded at 114 K in the case of the specimen containing silver nanowires grown within the mica structure. This is believed to arise due to formation of a nanojunction between the metal nanowire and silver nanoparticles with diameters of less than 3 nm. The latter were earlier shown to behave as insulators.