Electrical impedance spectroscopic investigations of monodispersed SiO2 nanospheres

Dielectric analysis of uniform and monodispersed SiO2 nanospheres at various temperatures in the frequency range 1 Hz-1 MHz is reported. The high optical transmittance and the presence of silica network in the synthesized product are evident from UV-vis and FTIR spectroscopic techniques respectively. The amorphous structure of SiO2 nanospheres is investigated by powder XRD pattern and uniform spherical morphology is visualized by FESEM analysis. The X-ray photoelectron spectroscopy elucidated the exact valence states of the SiO2 nanospheres. The temperature dependent dielectric parameters such as, dielectric constant (εr) and loss factor (tan δ) are decreased with increasing applied frequency and became static at higher frequencies. SiO2 nanospheres exhibited high dielectric constant (εr = 68) and low loss factor (tan δ = 0.0079) at 40 °C at 1 MHz. The activation energy (Ea) and relaxation time constant (τ) are calculated and the equivalent circuit model is developed to describe the electrical behaviour of the material.