Colloidal Nanocrystals of Wurtzite Zn 1-xCox0 (0 ≤ x ≥ 1) Models of Spinodal Decomposition in an Oxide Diluted Magnetic Semiconductor

Journal Article · Tue Nov 25 04:00:00 EST 2008 · Chemistry of Materials, 20(22):7107-7116

DOI:https://doi.org/10.1021/cm802280g· OSTI ID:1006327

White, Michael A; Ochsenbein, Stefan T; Gamelin, Daniel R

Magnetic-ion-rich nanoscale inclusions formed by spinodal decomposition have been observed in many diluted magnetic semiconductors and have recently been implicated in the ferromagnetic ordering observed in some of these materials. In this study, colloidal nanocrystals of the ternary alloy wurtzite Zn1-xCoxO, with x ranging from 0.0 (w-ZnO) to 1.0 (w-CoO), have been synthesized as model systems for the proposed spinodal decomposition nanostrucures of ferromagnetic Zn1-xCoxO thin films and powders. As freestanding nanocrystals, these phases do not show any signs of ferromagnetism or superparamagnetism at any value of x. Changes in the electronic absorption and magnetic circular dichroism (MCD) spectra with x are described that should allow optical identification of spinodal decomposition in other Zn1-xCoxO samples. Optical and magneto-optical spectroscopic results are presented for the end member of this series (w-CoO), apparently for the first time, and show this binary oxide to be an indirect gap chargetransfer insulator with Eg ≈ 2.3 eV.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1006327
• Journal Information: Chemistry of Materials, 20(22):7107-7116, Journal Name: Chemistry of Materials, 20(22):7107-7116 Journal Issue: 22 Vol. 20; ISSN CMATEX; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION
ALLOYS
Environmental Molecular Sciences Laboratory
FERROMAGNETISM
MAGNETIC CIRCULAR DICHROISM
MAGNETIC SEMICONDUCTORS
OXIDES
SPECTRA
SUPERPARAMAGNETISM
THIN FILMS