Crystallization of ZnO in Aqueous Precursor Solution at 90 °C

Abstract

ZnO crystallization from suitable aqueous precursor solutions is well known, albeit with crystal growth modifiers and high calcination temperatures. However, processing parameters such as molarity, pH, stirring, and mixing of the reacting solutions can be controlled to make the reactants react at lower activation energies (also implying lower crystal growth temperatures) to obtain the final product. The motivation behind this work is to show that by proper mixing and stirring and using appropriate molarities of the reactants, the kinetics of ZnO formation can be designed, and highly crystalline and oriented ZnO can be obtained with ease. In this work, 0.1 M zinc acetate and 8 M KOH aqueous solutions are slowly mixed while stirring and then reacted at 90 °C to obtain wurtzite crystal structured ZnO without calcination at high temperatures.

Highly Efficient and Reproducible Sonochemical Synthesis of ZnO Nanocrystals

“…From the morphological and structural characterizations, it can be supposed that hexagonal platelets are the initial growth crystalline units, according to observations by Katarapu et al. [25] Crystallite, after nucleation, usually develops into a macroscopic crystal with well-defined crystallographic faces which are related to different crystal planes that generally show differences in growth rate. In ZnO, Laudise [37] firstly observed the relationship between growth rates in different directions that is:…”

“…The thermal treatment conditions were chosen from literature to obtain directly ZnO without requiring the calcination process. [25,26] Those were made as reference samples with the purpose to compare them with ZnO materials obtained through combined thermal and ultrasonic treatment for which the morphology and crystalline structure were investigated at different treatment times (0-9 hours).…”