Giant dielectric permittivity in interrupted silver nanowires grown within mesoporous silica

Nanoglasses in the system Ag₂O-SiO₂ were formed within the pores of mesoporous silica SBA-15 (Santa Barbara Amorphous). Silver nanowires of diameter 5 nm were grown within SBA-15 by the process of electrodeposition. The nanowires were disrupted by applying a suitable voltage pulse. Detailed transmission and scanning electron microscopy studies were carried out. The disrupted silver strands were found to have an average length of 90 nm. The density of interrupted strands was estimated from the electron micrographs and found to have values in the range (10-20) 10¹⁰ cm^-2. Dielectric constant and dielectric loss factors of the nanocomposites of disrupted silver strand - containing Ag₂O-SiO₂ glass and SBA-15 were found to have values in the range 200-300 and 0.014-0.008 respectively at frequencies in the range 10 kHz-2 MHz. These values were found to be in satisfactory agreement with the theoretical model of Rice and Bernasconi emanating from the theory of Gorkhov and Eliashberg. These nanocomposites are expected to be useful in the fabrication of supercapacitors, after developing suitable electrode system for the material.