Radiation damage in 4H-SiC samples implanted by 70 keV oxygen ion beams was studied using photoluminescence and electron spin resonance techniques. ESR peak of g = 2.0053 and two zero-phonon lines were observed with the implanted samples. Combined with theoretical calculations, we found that the main defect in the implanted 4H-Si C samples was oxygen-vacancy complex. The calculated defect formation energies showed that the oxygen-vacancy centers were stable in n-type 4H-Si C.Moreover, the V_(Si)O_C^0 and V_(Si)O_C^(-1) centers were optically addressable. The results suggest promising spin coherence properties for quantum information science.
Related referential studies on gas-solid two-phase flows were briefly reviewed. Bubble ascending in a two-dimensional (2D) gas-solid fluidizedbed was studied both experimentally and numerically. A modified continuum model expressed in the conservation form was used in numericalsimulation. Solid-phase pressure was modeled via local sound speed; gas-phase turbulence was described by the K-ε two-equation model. Themodified implicit multiphase formulation (IMF) scheme was used to solve the model equations in 2D Cartesian/cylindrical coordinates. The bubbleascending velocity and particle motion in the 2D fluidized bed were measured using the photochromic dye activation (PDA) technique, which wasbased on UV light activation of particles impregnated with the dye. Effects of bed height and superficial gas velocity on bubble formation andascent were investigated numerically. The numerically obtained bubble ascending velocities were compared with experimental measurements. Gasbubble in jetting gas-solids fluidized bed was also simulated numerically.
Ruoyu HongZhiqiang RenJianmin DingM. KawajiHongzhong Li
Two-layer flow of magnetic fluid and non-magnetic silicone oil was simulated numerically. The continuity equation, momentum equations, kinematic equation, and magnetic potential equation were solved in two-dimensional Cartesian coordinate. PLIC (piecewise linear integration calculation) VOF (volume of fluid) scheme was employed to track the free interface. Surface tension was treated via a continuous surface force (CSF) model that ensures robustness and accuracy. The influences of applied magnetic field, inlet velocity profile, initial surface disturbance of interface and surface tension were analyzed. The computed interface shapes at different conditions were compared with experimental observation.
Ruoyu HongZhiqiang RenShizhong ZhangJianmin DingHongzhong Li
