ZnO microcrystal growth in hydrothermal processing with N ₂H ₄·H ₂O

ZnO microcrystal growth was investigated under a low temperature hydrothermal process with a relatively low concentration of N ₂H ₄·H ₂O (0.01-0.20mol/L). The nucleation and the growth rates of various crystal planes are strongly affected by the weak alkalinity of N ₂H ₄·H ₂O and the co-ordinative activity of N ₂H ₅ ⁺ ion. ZnO microcrystals change from oatmeal-like plate to hexagonal plate, and then to hexagonal rod-like cluster with increasing of N ₂H ₄·H ₂O concentrations, respectively. The nucleations of ZnO microcrystals are influenced by the alkaline dispersant and ultrasonic treatment. The solution of 0.20mol/L N ₂H ₄·H ₂O with the alkaline dispersant has a strong reducibility, which changes the mechanism of nucleation and growth of ZnO microcrystals. The center-hollow hexagonal rod-like ZnO clusters were obtained through the N ₂ bubble template-growth route.