Dependence of Lattice Distortion and Dielectric Response of Zinc Aluminate on Milling Frequency

Abstract

Zinc aluminate (ZnAl2O4) samples were prepared using nanomilling based solid state reaction method for several potential applications. Effect of milling frequency on structural and dielectric behavior of ZnAl2O4 has been explored systemically. Investigation of crystal structure reveals that change in lattice parameter by milling does not alter the cubic lattice of ZnAl2O4. This milling frequency at the nanosize resulted in a gradual decrease in the particle size, which can be attributed to the inhomogeneous defects. Grain size in nanometers has been calculated by XRD using Debye-Scherrer formula. Dielectric measurements performed in the range of 20Hz-20MHz confirms the Maxwell –Wagner two layer model which is consistent with the Koop’s theory. High value of ac conductivity indicates that milling blocked the ionic transport. As a result of Nyquist plots, a single semicircle was obtained which indicated the leading role of grain (bulk). The variation in the semicircle radii for different samples is due to the influence of milling frequency.