Spectroscopy and microscopy of doped TiO2 nanocrystalline materials
EMSL Project ID
2463
Abstract
We propose to synthesize and characterize by XRD, TEM, and possibly EPR spectroscopy a series of nanocrystalline ferromagnetic oxide semiconductor materials of direct relevance to spintronics applications. Our studies will focus on transition-metal doped Fe3O4 and TiO2 oxide semiconductors prepared by OPA-MBE as epitaxially-grown crystalline films (thickness = 10-100nm), as nanocrystalline (dia. = 1.5-10nm) colloid solutions, and as thin-film 2D arrays of nanocrystals. Our research will also include optical and magneto-optical spectroscopic experiments performed at the University of Washington, Seattle. Combined, these experiments will seek to address the change in electronic structure, magnetic, and magneto-optical properties of these materials as the nanoscale dimensionality is changed from 2D single crystal to zero-dimensional nanocrystals, and subsequently to 2D ordered nanoparticle arrays. Particular attention will be paid to the potential influence of quantum confinement on the observed physical properties. Proposed experiments to be performed at PNNL include OPA-MBE synthesis of Co2+, Fe2+, and possibly Cr3+-doped Fe2O3 and TiO2 crystalline films, powder XRD, low- and high-resolution TEM (JEOL 2010, 200kV, including x-ray dispersive spectroscopy for quantitative elemental analysis, high-resolution EDS or convergent beam diffraction for differentiating between internally doped and surface bound dopants, and diffraction mode TEM), and helium-temperature EPR spectroscopy (X-band, 2-300K).
Project Details
Project type
Exploratory Research
Start Date
2002-03-11
End Date
2005-02-17
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Bryan, J. D.; Heald, S. M.; Chambers, S. A.; Gamelin, D. R., Strong Room-Temperature Ferromagnetism in Co2+ - Doped TiO2 Made from Colloidal Nanocrystals. Journal of American Chemical Society 2004, 126, 11640-11647.
Bryan JD, SA Santangelo, SC Keveren, and DR Gamelin. 2005. "Activation of High-TC Ferromagnetism in Co2+:TiO2 and Cr3+:TiO2 Nanorods and Nanocrystals by Grain Boundary Defects ." Journal of the American Chemical Society 127(44):15568-15574. doi:10.1021/ja0543447
KR Kittilstved, JE Amonette, RK Kukkadapu, DA Schwartz, DR Gamelin, and Norberg NS. 2004. "Synthesis of Colloidal Mn2+:ZnO Quantum Dots and High-TC Ferromagnetic Nanocrystalline Thin Films." Journal of the American Chemical Society 126(30):9387-9398.