W. Kwang-Hua Chu

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Hybrid superconducting magnetic bearing (SMB), using YBCO high temperature superconductors (HTS) coupled with permanent magnets, has been implemented into a flywheel energy storage (FES) system prototype. The hybrid SMB design uses permanent magnets to levitate the rotor weighing 19 kg and superconductors to stabilize the inherently unstable magnet-magnet(More)
We have used RBS, XRD, Raman, and photoconductivity to characterize CdS thin films grown by single, continuous, and multiple dip chemical processes. XRD has shown, without ambiguity, that grown CdS films, independent of the process, in an almost homogeneous reaction free bath have a zincblende crystal structure where reflections from (111), (200), (220),(More)
1 MeV carbon ions were implanted into single-crystal copper which was then annealed in argon at temperatures ranging from 350 to 750 “C. Regrowth of the radiation-damaged copper was examined by RBS-channeling measurements. Carbon segregation occurred on annealing at 750°C. Prolonged annealing at 750 “C caused blistering of the copper layer over the buried(More)
Scientific efforts are growing to understand artificial BiFeO3/SrRuO3/SrTiO3-heterostructures, wherein an altered environment at each interface, caused by epitaxial strains, broken symmetry, off-stoichiometry and charge transfer, can generate a rich spectrum of exotic properties. Herein, (BiPb)FeO3/SrRuO3/SrTiO3-heterostructures were sputtered with various(More)
Despite intense research efforts into the development of GaN and AlN substrates, sapphire remains a popular substrate choice for III-N-based epitaxy of electronic and optoelectronic devices. With sapphire substrates, certain pre-growth procedures are used to wet the substrate surface and accommodate the high lattice mismatch between III-nitrides and Al/sub(More)
We present angular-dependent current-voltage (I-V) measurements in borocarbide YNi(2)B(2)C single crystals near the vortex-glass irreversible line. External magnetic fields are applied along the angle θ with respect to the c-axis. The nonlinear I-V curves reveal scaling behaviour near the transition. Using the scaling analysis, the relevant critical(More)
Growth mechanism of superconducting Hg-based cuprate thin films has been studied by changing the sample heating rate in Hg-vapor annealing process. A fast temperature ramping Hg-vapor annealing (FTRA) process has been found to be beneficial to the growth of high quality c-axis oriented epitaxial HgBa/sub 2/CaCu/sub 2/O/sub 6+/spl delta// films with(More)
Efficient conversion of solar energy into electricity is crucial to the use of renewable energy. Among the various semiconductors being investigated for photovoltaic conversion, III- nitrides are fervently pursued because of their band gap tenability from 0.65 eV to 3.4 eV by adjusting the indium concentration of In<sub>X</sub>Ga<sub>1-X</sub>N alloys. This(More)
The transfer of momentum between a permanent magnet and a type II superconductor without mutual physical contact is the central theme behind many mechanical applications of the new class of high-temperature ceramic superconductors. The properties of this momentum transfer and its applications were studied in a series of experiments as a proof of principle.(More)