<link rel="stylesheet" href="styles.cf390c6bfbe7555f.css">

Browsing by Author "Chen, Yong-Lun"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item type:Item,
    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.
  • Thumbnail Image
    Item type:Item,
    Epitaxial NiO nanocrystals: a dimensional analysis
    (2013-06-01)
    Cheung, Jeffrey
    ;
    Okatan, Mahmut Baris
    ;
    Sullaphen, Jivika
    ;
    Cheng, Xuan
    ;
    Nagarajan, Valanoor
    We present the study of the synthesis of (001) nickel oxide (NiO) epitaxial nanocrystals grown on (001) strontium titanate (SrTiO3) single crystal substrates. Pulsed laser deposition of the bismuth nickel oxide (BiNiO3, BNO) perovskite precursor followed by post-deposition processing is carried out to form the NiO nanocrystals. A detailed analysis of the dimensions of nanocrystals reveals that the morphology attained differs from the thermodynamically expected equilibrium shape. The deviations from the equilibrium shape are found to follow a systematic trend where the in-plane basal dimensions, that is, the length and width of the nanocrystals grown differ in discretized dimensions. This discretization suggests that for a given interfacial area of nanocrystals there are multiple stable basal rectangular geometries attainable.
  • Thumbnail Image
    Item type:Item,
    Self-Assembled Epitaxial Core-Shell Nanocrystals with Tunable Magnetic Anisotropy
    (2015-09-02)
    Liao, Sheng-Chieh
    ;
    Chen, Yong-Lun
    ;
    Kuo, Wei-Cheng
    ;
    Cheung, Jeffrey
    ;
    Wang, Wei-Cheng