Extended solubility of CoO in ZnO and effects on magnetic properties

Tobias A. Schaedler, Ashutosh S. Gandhi, Mitsuhiro Saito, Manfred Rühle, Richard Gambino, Carlos G. Levi

    Research output: Contribution to journalArticlepeer-review

    12 Citations (Scopus)

    Abstract

    The metastable solid solubility extension of CoO in ZnO (wurtzite) was investigated in precursor-derived powders as well as in thin films grown on sapphire substrates by pulsed laser deposition. A maximum solubility of 30% Co2+ in ZnO was achieved in the powders. Transmission electron microscopy (TEM) of the films revealed them to have grown epitaxially and retained up to nearly 40% CoO in solid solution, but some Co2+ precipitated as rock-salt. The temperature dependence of the metastable solubility limit in the ZnO-CoO system was assessed and is discussed in terms of the relevant thermodynamic factors. The magnetic properties of n-type conductive Zn0.79 Co0.2Al0.01O films were studied, yielding evidence of a ferromagnetic phase with a TC of 25 K and a second, magnetically ordered, phase with positive exchange and arguably a TC of ∼250 K. Connections between the properties and microstructural observations in high resolution TEM are proposed.

    Original languageEnglish
    Pages (from-to)791-801
    Number of pages11
    JournalJournal of Materials Research
    Volume21
    Issue number3
    DOIs
    Publication statusPublished - 2006 Mar 1

    ASJC Scopus subject areas

    • Materials Science(all)
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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