Browsing by Author "Bogle, Kashinath A."

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Epitaxial Magnetic Oxide Nanocrystals Via Phase Decomposition of Bismuth Perovskite Precursors
(2012-12-19)
Bogle, Kashinath A.
;
Cheung, Jeffrey
;
Chen, Yong-Lun
;
Liao, Sheng-Chieh
;
Lai, Chih-Hung
The phase instability of bismuth perovskite (BiMO3), where M is a ferromagnetic cation, is exploited to create self-assembled magnetic oxide nanocrystal arrays on oxide supports. Conditions during pulsed laser deposition are tuned so as to induce complete breakdown of the perovskite precursor into bismuth oxide (Bi2O3) and metal oxide (M-Ox) pockets. Subsequent cooling in vacuum volatizes the Bi2O3 leaving behind an array of monodisperse nanocrystals. In situ reflective high energy electron diffraction beam is exploited to monitor the synthesis in real-time. Analysis of the patterns confirms the phase separation and volatization process. Successful synthesis of M-Ox, where M = Mn, Fe, Co, and Cr, is shown using this template-free facile approach. Detailed magnetic characterization of nanocrystals is carried out to reveal the functionalities such as magnetic anisotropy as well as larger than bulk moments, as expected in these oxide nanostructures.
Synthesis of Epitaxial Metal Oxide Nanocrystals via a Phase Separation Approach
(2010-09-01)
Bogle, Kashinath A.
;
Anbusathaiah, Varatharajan
;
Arredondo, Miryam
;
Lin, Jiunn-Yuan
;
Chu, Ying-Hao
Perovskite phase instability of BiMnO(3) has been exploited to synthesize epitaxial metal oxide magnetic nanocrystals. Thin film processing conditions are tuned to promote the breakdown of the perovskite precursor into Bi(2)O(3) matrix and magnetic manganese oxide islands. Subsequent cooling in vacuum ensures complete volatization of the Bi(2)O(3), thus leaving behind an array of self-assembled magnetic Mn(3)O(4) nanostructures. Both shape and size can be systematically controlled by the ambient oxygen environments and deposition time. As such, this approach can be extended to any other Bi-based complex ternary oxide system as it primarily hinges on the breakdown of parent Bi-based precursor and subsequent Bi(2)O(3) volatization.