### Session P10: Focus Session: Magnetic Semiconductors: Oxides

11:15 AM–2:03 PM, Wednesday, March 23, 2005
LACC Room: 153B

Chair: Christoph Adelmann, University of Minnesota

Abstract ID: BAPS.2005.MAR.P10.4

### Abstract: P10.00004 : Structure and magnetic properties of Co doped anatase TiO2 particles

11:51 AM–12:03 PM

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#### Authors:

Hao Zhu
Lubna Shah
Yuwen Zhao
John Q. Xiao
(Physics and Astronomy Department, University of Delaware)

Mohamed A. Barakat
G. Hayes
Ismat Shah
(Materials Science and Engineering Dept, University of Delaware)

Co$_{0.028}$Ti$_{0.972}$O$_{2-\delta }$was synthesized via sol-gel method. It's annealed at 600$^{\circ}$C for one hour in air. The X-Rays diffraction study confirmed that samples are of anatase structure and no detectable cobalt clusters or other impurities are observed. The magnetic properties are characterized by SQUID in a broad temperature range 5K $\sim$ 300K, and no ferromagnetic property was observed. The magnetization verse temperature curve fits well with the Curie-Weiss law and the extracted atomic effective moment suggests that the Co(III) is in high spin state. These paramagnetic particles can be turned into ferromagnetic phase with a Curie temperature above 300K after heat treatment in a mixture of H$_{2}$ and Ar gases at 600$^{\circ}$C for one hour. The origin of ferromagnetism has been studied by XPS, SQUID, XRD and TEM.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.MAR.P10.4