Growth of zinc oxide nanorod structures: pressure controlled hydrothermal process and growth mechanism

• Published in: Journal of materials science Vol. 52; no. 4; pp. 2007 - 2020
• Main Authors: Vasireddi, R., Javvaji, B., Vardhan, H., Mahapatra, D. R., Hegde, G. M.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2017; Springer; Springer Nature B.V
• Subjects: Analysis; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Crystallography and Scattering Methods; Materials Science; Molecular dynamics; Morphology; Nanorods; Nanostructure; Original Paper; Polymer Sciences; Pressure effects; Process controls; Process parameters; Simulation; Solid Mechanics; Substrates; Vapor pressure; Wurtzite; Zinc oxide; Zinc oxides; Ionized Oxygen Molecules; Zinc Substrate; Nanorod Diameter; ZnO Nanorods; Nanorod Growth
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-016-0489-0

Zinc oxide (ZnO) nanorods of various morphologies are grown on zinc substrate by pressure-assisted hydrothermal process and the growth mechanism is investigated with the help of molecular dynamics (MD) simulation results. Hydrothermally reacted ZnO 2 nanostructure bottom-up formation from Zn substrate is a useful process employed here. A systematic study on the role of process control parameters such as pressure and temperature on nanorod growth has been carried out. Correlation among the process parameters to form ordered nanostructures is established. The effect of pressure on the diameter and length of the grown ZnO nanorod structures is studied, which is precisely tunable. With a decrease in pressure from 500 to 400 kPa, the nanorod diameter is reduced by 22.2 %, while its length is increased by 24.8 %. At lower vapor pressure, the nanorod tips are sharper, whereas at higher vapor pressure they are flat. These variations along with a detailed analysis of MD simulations helps us hypothesize that pressure plays an important role in governing the diffusion of oxygen atom onto zinc surface and generating wurtzite phase. Simulation results clearly show that ZnO nanorods lift off due to their interaction with the Zn atoms on the substrate and the resulting forces.