A Study of Microstructural Models of Li-doped ZnO Ceramic for Piezoelectric Application

Abstract

Structural and microstructural properties of Zn_1-xLi_xO (0.00 ≤x≤ 0.50) ceramics were carried out using X-ray Diffraction (XRD) showed that the samples were polycrystalline with hexagonal wurtzite structure. The average crystallite size was estimated using three models, all of which showed decrement with increased lithium-doping. The crystallite size increased systematically, with the largest value being 200 nm in the Li-doped ZnO in x=0.3. However, microstrain was fairly constant for all doped samples with a value of ~0.006, the value for the pristine being 0.001. Of the three models, the comparison showed that the Scherer model had the smallest crystallite size due to the neglect of strain, whereas the W-H model had the largest in the doped samples, with crystallite size ~200 nm, but with subsequent decrease observed which is attributed to the assumption of isotropy in the model. The c/a ratio indicated a consistent hexagonal structure despite lithium-doping. Energy Dispersive Spectroscopy (EDS) showed that all the nominal elements compositions were present. A decrease in grain size with the increase in lithium-doping was observed with the lowest grain size (0.2 μm) observed in x=0.5, thus making it the specimen with the highest potential for piezoelectric application.