Hierarchical Hollow Spheres of ZnO and Zn1−xCoxO: Directed Assembly and Room-Temperature Ferromagnetism

Yongcai Qiu, Wei Chen, Shihe Yang*, B. Zhang, X. X. Zhang, Y. C. Zhong, K. S. Wong

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


A novel water-bubble template process has been developed to synthesize uniform hierarchical hollow spheres of ZnO and transition metal doped ZnO in ethylene glycol. For undoped ZnO, nanorods are formed due to the preferred c-axial growth and assembled into highly regular hollow spheres. Co-doped ZnO, in contrast, favors lateral growth into nanodisks because of the deterred c-axial extension caused by the Co dopants. Nevertheless, the Zn 1-xCoxO (x = ∼0.59%, ∼1.62%, ∼5.21%) nanodisks, albeit with a very different morphology from the nanorods, are also assembled cleanly into high-quality hollow spheres. The synthesis conditions have been carefully studied and the products have been extensively characterized by a variety of techniques. In particular, Raman scattering and photoluminescence spectra of the Zn1-xCoxO hollow spheres prove that the Co atoms occupy the Zn sites of wurtzite ZnO. Also, room temperature magnetic measurements show robust coercivities, signifying the ferromagnetism that is characteristic of dilute magnetic semiconductors (DMS).

Original languageEnglish (US)
Pages (from-to)177-183
Number of pages7
JournalCrystal Growth and Design
Issue number1
StatePublished - Jan 6 2010

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics


Dive into the research topics of 'Hierarchical Hollow Spheres of ZnO and Zn1−xCoxO: Directed Assembly and Room-Temperature Ferromagnetism'. Together they form a unique fingerprint.

Cite this