Effect of γ-Irradiation on the Dielectric and Conductivity Properties of Nano-Wollastonite

Abstract

Nanocrystalline porous CaSiO 3 ceramic powders have been synthesized by a novel low-temperature initiated self-propagating, gas-producing solution combustion method. Single phase β-CaSiO 3 (Wollastonite) is formed by calcination at 900• C for 3 h. The crystallization and phase formation temperatures in this method are found to be lower compared to the powder obtained via solid state reaction method. The powder is characterized by powder XRD (X-Ray Diffraction), and crystallite sizes are evaluated using Scherrer's formula as well as from TEM (Transmission Electron Microscopy). The Wollastonite powder is exposed to 60 Co γ-radiation to accumulated doses of 1, 3, and 5 KGy and low-frequency (10 2 -10 6 Hz) dielectric measurements are carried out before and after irradiation. The dielectric conductivity is estimated from the dielectric constant and loss tangent. Exposure to γ-radiation results in substantial modification in the properties of the ceramic powder due to changes in the porosity of the material. The correlation between dielectric and conductivity properties is discussed in relation to porosity effect.

Structural and Dielectrical Properties of Sterilized Human Teeth

“…3 that, the dielectrical constant decreased sharply with frequency up to 1 kHz and more slowly in the higher frequency region for the control and irradiated dentin. This feature is similar to those observed in β-CaSiO3 powders (Kulkarni et al, 2011). In addition, the dielectrical constant for the irradiated samples was smaller than the control overall frequency range.…”

“…The effect of γ-irradiation on the dielectrical properties and conductivity behavior of nanowollastonite was previously reported (Kulkarni et al, 2011). It was found that, the exposure to γ-radiation results in substantial modification in the properties of the ceramic powder due to changes in the porosity of the material.…”

Dielectric and electrical studies of Pr3+ doped nano CaSiO3 perovskite ceramics

“…A higher value of 'n' implies that large energy is stored in such collective motions [19]. The value of n is 0.90 for un-doped sample [9]. With doping, the conductivity is found to increase as the grain resistance dominates over grain boundary resistance, and the value of n increases to 0.92.…”

“…A normal relaxation was observed in undoped nano CaSiO 3 ceramic prepared by solution combustion method and no relaxation peak was observed in loss tangent plot versus frequency [9]. Thus the electrical microstructure of undoped nano CaSiO 3 is homogeneous and hence its dielectric behaviour does not follow the Maxwell Wagner (MW) relaxation.…”

“…Impedance spectroscopy can reveal such compositional variations while it may be difficult to detect such compositional variations by electron microscopy. N Tangboriboon et al have prepared CaSiO 3 using eggshell and fumed silica by Sol-gel method and have observed high dielectric constant [8], whereas a different value of dielectric constant was observed for nano CaSiO 3 , prepared by solution combustion process in our previous work [9].…”