Affordable Access

deepdyve-link
Publisher Website

Shape-selective dependence of room temperature ferromagnetism induced by hierarchical ZnO nanostructures.

Authors
  • Motaung, D E
  • Mhlongo, G H
  • Nkosi, S S
  • Malgas, G F
  • Mwakikunga, B W
  • Coetsee, E
  • Swart, H C
  • Abdallah, H M I
  • Moyo, T
  • Ray, S S
Type
Published Article
Journal
ACS Applied Materials & Interfaces
Publisher
American Chemical Society
Publication Date
Jun 25, 2014
Volume
6
Issue
12
Pages
8981–8995
Identifiers
DOI: 10.1021/am501911y
PMID: 24896749
Source
Medline
License
Unknown

Abstract

We report on the room temperature ferromagnetism of various highly crystalline zinc oxide (ZnO) nanostructures, such as hexagonally shaped nanorods, nanocups, nanosamoosas, nanoplatelets, and hierarchical nano "flower-like" structures. These materials were synthesized in a shape-selective manner using simple microwave assisted hydrothermal synthesis. Thermogravimetric analyses demonstrated the as-synthesized ZnO nanostructures to be stable and of high purity. Structural analyses showed that the ZnO nanostructures are polycrystalline and wurtzite in structure, without any secondary phases. Combination of electron paramagnetic resonance, photoluminescence, and X-ray photoelectron spectroscopy studies revealed that the zinc vacancies (VZn) and singly ionized oxygen vacancies (VO(+)) located mainly on the ZnO surface are the primary defects in ZnO structures. A direct link between ferromagnetism and the relative occupancy of the VZn and VO(+) was established, suggesting that both VZn and VO(+) on the ZnO surface plays a vital role in modulating ferromagnetic behavior. An intense structure- and shape-dependent ferromagnetic signal with an effective g-value of >2.0 and a sextet hyperfine structure was shown. Moreover, a novel low field microwave absorption signal was observed and found to increase with an increase in microwave power and temperature.

Report this publication

Statistics

Seen <100 times