The Experts below are selected from a list of 138 Experts worldwide ranked by ideXlab platform
C W Lan - One of the best experts on this subject based on the ideXlab platform.
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effects of cycle patterns of accelerated crucible rotation technique acrt on the flows interface and segregation in vertical Bridgman Crystal Growth
International Journal of Heat and Mass Transfer, 2007Co-Authors: Yu Cheng Liu, Bernard Roux, C W LanAbstract:The accelerated crucible rotation technique (ACRT) has been used extensively in Crystal Growth for the control of flow and segregation. However, the amelioration of the spin-up and spin-down flows for a favorable Growth has not yet been fully understood. In this study, we investigate several ACRT schemes and discuss their effects on the flow, interface morphology, and solute segregation during the vertical Bridgman Growth of succinonitrile (SCN) containing acetone. Both numerical simulation and visualization experiments are conducted. In addition to the triangular and trapezoidal patterns, stair-up, stair-down, and pulse schemes are proposed for a better flow and mixing control without much interface deformation. For all the ACRT schemes investigated here, the simulated results are in good agreement with the observed ones.
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effects of accelerated crucible rotation on segregation and interface morphology for vertical Bridgman Crystal Growth visualization and simulation
Journal of Crystal Growth, 2007Co-Authors: Yu Cheng Liu, Bernard Roux, C W LanAbstract:Abstract The effects of accelerated crucible rotation technique (ACRT) on the segregation, interface shape, and morphological instability during vertical Bridgman (VB) Crystal Growth of succinonitrile (SCN) containing 0.064 wt% acetone were investigated by visualization experiments and computer simulation. It was found that ACRT was effective in reducing time-averaged constitutional supercooling and thus the morphological instability. However, at low rotation amplitudes, the morphology was less stable and the breakdown area was found to be wider as a result of flow transition. The simulated interface shapes were in good agreement with the observed ones. In addition, the onset of morphological breakdown was consistent with the numerical prediction based on the time-averaged constitutional supercooling.
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dynamic three dimensional simulation of facet formation and segregation in Bridgman Crystal Growth
Journal of Crystal Growth, 2007Co-Authors: C W Lan, Chunwei ChenAbstract:Abstract Facet formation is an important kinetic phenomenon during Crystal Growth and its simulation remains a non-trivial task in Crystal-Growth modeling. Numerical models for facet formation have been developed, and its dynamic three-dimensional (3D) simulations, coupled heat flow and segregation in a Bridgman Growth process are presented. The Growth of yttrium aluminum garnet (YAG) Crystals in the [1 1 1] direction having {1 1 1}, {2 1 1}, and {1 1 0} facets are taken as examples. Two numerical schemes for the interface tracking based on the geometric and kinetic models are considered, and the calculated results are found in good agreement. By using different segregation coefficients at the facets and the rough surface, both radial and axial abnormal segregations, such as the dark core, due to facet formation are further simulated. Multiple facets are considered as well.
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effects of angular vibration on the flow segregation and interface morphology in vertical Bridgman Crystal Growth
International Journal of Heat and Mass Transfer, 2007Co-Authors: Z B Chen, Bernard Roux, T. P. Lyubimova, W T Hsu, C W LanAbstract:Abstract The effect of angular vibration on the flow, segregation, and interface morphology during vertical Bridgman Crystal Growth was investigated. Transparent experiments using SCN containing about 0.02 wt.% acetone were performed. To simulate the observed results, both direct numerical simulation (DNS) and Schlichting boundary layer approximation (SBLA) were considered in the computer model. The simulated morphological breakdown patterns, as a result of acetone accumulation (segregation), are consistent with the experimental observation. At high frequency with low amplitudes, both simulation approaches gave consistent results. However, care must be taken in using SBLA for low frequency vibration of several hertz.
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thermal solutal flows and segregation and their control by angular vibration in vertical Bridgman Crystal Growth
Chemical Engineering Science, 2006Co-Authors: Yu Cheng Liu, Bernard Roux, T. P. Lyubimova, C W LanAbstract:Abstract Thermal–solutal flows and their induced segregation and supercooling are important in the Growth of an alloy Crystal. For the vertical Bridgman Crystal Growth having a stabilized thermal profile, in addition to the thermal convection induced by radial thermal gradients, solute gradients can either induce or suppress the flow depending on the solute density. Such thermal–solutal flows significantly affect the segregation behavior, constitutional supercooling, and thus the morphological instability of the solidification front. A transparent Bridgman Growth of succinonitrile containing a lighter (acetone) or heavier (salol) solute was investigated. The evolution of the interface shape as well as morphological instability was visualized and was interpreted through computer simulation. To further control the flow and segregation, angular vibration was applied and its effects on the thermal–solutal flows and morphological instability were investigated.
Bernard Roux - One of the best experts on this subject based on the ideXlab platform.
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effects of cycle patterns of accelerated crucible rotation technique acrt on the flows interface and segregation in vertical Bridgman Crystal Growth
International Journal of Heat and Mass Transfer, 2007Co-Authors: Yu Cheng Liu, Bernard Roux, C W LanAbstract:The accelerated crucible rotation technique (ACRT) has been used extensively in Crystal Growth for the control of flow and segregation. However, the amelioration of the spin-up and spin-down flows for a favorable Growth has not yet been fully understood. In this study, we investigate several ACRT schemes and discuss their effects on the flow, interface morphology, and solute segregation during the vertical Bridgman Growth of succinonitrile (SCN) containing acetone. Both numerical simulation and visualization experiments are conducted. In addition to the triangular and trapezoidal patterns, stair-up, stair-down, and pulse schemes are proposed for a better flow and mixing control without much interface deformation. For all the ACRT schemes investigated here, the simulated results are in good agreement with the observed ones.
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effects of accelerated crucible rotation on segregation and interface morphology for vertical Bridgman Crystal Growth visualization and simulation
Journal of Crystal Growth, 2007Co-Authors: Yu Cheng Liu, Bernard Roux, C W LanAbstract:Abstract The effects of accelerated crucible rotation technique (ACRT) on the segregation, interface shape, and morphological instability during vertical Bridgman (VB) Crystal Growth of succinonitrile (SCN) containing 0.064 wt% acetone were investigated by visualization experiments and computer simulation. It was found that ACRT was effective in reducing time-averaged constitutional supercooling and thus the morphological instability. However, at low rotation amplitudes, the morphology was less stable and the breakdown area was found to be wider as a result of flow transition. The simulated interface shapes were in good agreement with the observed ones. In addition, the onset of morphological breakdown was consistent with the numerical prediction based on the time-averaged constitutional supercooling.
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effects of angular vibration on the flow segregation and interface morphology in vertical Bridgman Crystal Growth
International Journal of Heat and Mass Transfer, 2007Co-Authors: Z B Chen, Bernard Roux, T. P. Lyubimova, W T Hsu, C W LanAbstract:Abstract The effect of angular vibration on the flow, segregation, and interface morphology during vertical Bridgman Crystal Growth was investigated. Transparent experiments using SCN containing about 0.02 wt.% acetone were performed. To simulate the observed results, both direct numerical simulation (DNS) and Schlichting boundary layer approximation (SBLA) were considered in the computer model. The simulated morphological breakdown patterns, as a result of acetone accumulation (segregation), are consistent with the experimental observation. At high frequency with low amplitudes, both simulation approaches gave consistent results. However, care must be taken in using SBLA for low frequency vibration of several hertz.
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thermal solutal flows and segregation and their control by angular vibration in vertical Bridgman Crystal Growth
Chemical Engineering Science, 2006Co-Authors: Yu Cheng Liu, Bernard Roux, T. P. Lyubimova, C W LanAbstract:Abstract Thermal–solutal flows and their induced segregation and supercooling are important in the Growth of an alloy Crystal. For the vertical Bridgman Crystal Growth having a stabilized thermal profile, in addition to the thermal convection induced by radial thermal gradients, solute gradients can either induce or suppress the flow depending on the solute density. Such thermal–solutal flows significantly affect the segregation behavior, constitutional supercooling, and thus the morphological instability of the solidification front. A transparent Bridgman Growth of succinonitrile containing a lighter (acetone) or heavier (salol) solute was investigated. The evolution of the interface shape as well as morphological instability was visualized and was interpreted through computer simulation. To further control the flow and segregation, angular vibration was applied and its effects on the thermal–solutal flows and morphological instability were investigated.
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reversing radial segregation and suppressing morphological instability during Bridgman Crystal Growth by angular vibration
Journal of Crystal Growth, 2004Co-Authors: Z B Chen, Bernard Roux, T. P. Lyubimova, W T Hsu, C W LanAbstract:During vertical Bridgman Crystal Growth, local solute accumulation along the freezing interface due to buoyancy often causes radial non-uniformity and pit formation, which accelerate morphological instability. A novel approach by using angular vibration has been proposed. Through the visualization of the freezing interface during directional solidification of succinonitrile containing acetone, it was shown that angular vibration about the Growth axis was effective in reversing radial segregation and thus enhancing morphological stability. Simulation was conducted and good agreement was found.
Yu Cheng Liu - One of the best experts on this subject based on the ideXlab platform.
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effects of cycle patterns of accelerated crucible rotation technique acrt on the flows interface and segregation in vertical Bridgman Crystal Growth
International Journal of Heat and Mass Transfer, 2007Co-Authors: Yu Cheng Liu, Bernard Roux, C W LanAbstract:The accelerated crucible rotation technique (ACRT) has been used extensively in Crystal Growth for the control of flow and segregation. However, the amelioration of the spin-up and spin-down flows for a favorable Growth has not yet been fully understood. In this study, we investigate several ACRT schemes and discuss their effects on the flow, interface morphology, and solute segregation during the vertical Bridgman Growth of succinonitrile (SCN) containing acetone. Both numerical simulation and visualization experiments are conducted. In addition to the triangular and trapezoidal patterns, stair-up, stair-down, and pulse schemes are proposed for a better flow and mixing control without much interface deformation. For all the ACRT schemes investigated here, the simulated results are in good agreement with the observed ones.
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effects of accelerated crucible rotation on segregation and interface morphology for vertical Bridgman Crystal Growth visualization and simulation
Journal of Crystal Growth, 2007Co-Authors: Yu Cheng Liu, Bernard Roux, C W LanAbstract:Abstract The effects of accelerated crucible rotation technique (ACRT) on the segregation, interface shape, and morphological instability during vertical Bridgman (VB) Crystal Growth of succinonitrile (SCN) containing 0.064 wt% acetone were investigated by visualization experiments and computer simulation. It was found that ACRT was effective in reducing time-averaged constitutional supercooling and thus the morphological instability. However, at low rotation amplitudes, the morphology was less stable and the breakdown area was found to be wider as a result of flow transition. The simulated interface shapes were in good agreement with the observed ones. In addition, the onset of morphological breakdown was consistent with the numerical prediction based on the time-averaged constitutional supercooling.
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thermal solutal flows and segregation and their control by angular vibration in vertical Bridgman Crystal Growth
Chemical Engineering Science, 2006Co-Authors: Yu Cheng Liu, Bernard Roux, T. P. Lyubimova, C W LanAbstract:Abstract Thermal–solutal flows and their induced segregation and supercooling are important in the Growth of an alloy Crystal. For the vertical Bridgman Crystal Growth having a stabilized thermal profile, in addition to the thermal convection induced by radial thermal gradients, solute gradients can either induce or suppress the flow depending on the solute density. Such thermal–solutal flows significantly affect the segregation behavior, constitutional supercooling, and thus the morphological instability of the solidification front. A transparent Bridgman Growth of succinonitrile containing a lighter (acetone) or heavier (salol) solute was investigated. The evolution of the interface shape as well as morphological instability was visualized and was interpreted through computer simulation. To further control the flow and segregation, angular vibration was applied and its effects on the thermal–solutal flows and morphological instability were investigated.
T Duffar - One of the best experts on this subject based on the ideXlab platform.
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numerical study of boundary condition influence on convective flow and heat mass transfer during concentrated alloy Bridgman Crystal Growth
Modelling and Simulation in Materials Science and Engineering, 2007Co-Authors: M P Marchenko, T DuffarAbstract:This paper is devoted to the numerical investigation of the influence of Growth conditions (external temperature regime, crucible design) on convection motion and heat-mass transfer in the melt and then on Crystal composition, during InxGa1−xSb Crystal Growth by the Bridgman method. Thermocouple data of Crystal Growth experiments were used as boundary conditions for mathematical modelling. Calculations were performed for a two part crucible composed of BN and silica according to the experimental conditions. Numerical results show good agreement with the experimental data of the melt/Crystal (m/c) interface and the Crystal composition. The dependence of complex non-linear Crystallization dynamics on boundary conditions, on rejection of heavy InSb, phase diagram and thermosolutal convection is also studied. As was shown in the mathematical modelling, Crystal composition heterogeneity is caused by a stagnant flow zone close to the interface. According to the analysis of experimental thermocouple data, it was found that the side wall temperature gradient increased during time. Simulations showed that the time interval of the gradient increase concurred with the m/c interface passing through the crucible junction. As a result, mathematical modelling clarified that the improved homogeneity of the Crystal grown after the crucible junction consists of the increase in the thermal gradient.
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optimization of the Bridgman Crystal Growth process
Journal of Crystal Growth, 2004Co-Authors: M Margulies, P Witomski, T DuffarAbstract:Abstract A numerical optimization method of the vertical Bridgman Growth configuration is presented and developed. It permits to optimize the furnace temperature field and the pulling rate versus time in order to decrease the radial thermal gradients in the sample. Some constraints are also included in order to insure physically realistic results. The model includes the two classical non-linearities associated to Crystal Growth processes, the radiative thermal exchange and the release of latent heat at the solid–liquid interface. The mathematical analysis and development of the problem is shortly described. On some examples, it is shown that the method works in a satisfactory way; however the results are dependent on the numerical parameters. Improvements of the optimization model, on the physical and numerical point of view, are suggested.
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Bridgman Crystal Growth and defect formation in gasb
Journal of Crystal Growth, 1999Co-Authors: P Boiton, T Duffar, N Giacometti, J L Santailler, Pierre Dusserre, J P NabotAbstract:Abstract 2″ GaSb single Crystals have been grown by the vertical Bridgman method. It is shown that encapsulation by a molten salt is necessary to avoid spurious nucleation and sticking of the Crystal on the crucible, both the phenomena being deleterious to the Crystal quality. Twinning, observed even during Growth under encapsulant, has been decreased by an increase of the thermal gradient applied along the crucible. Single Crystals present structural and electronic properties close to the classical values reported for undoped GaSb grown by the Czochralski or LEC techniques.
T. P. Lyubimova - One of the best experts on this subject based on the ideXlab platform.
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the influence of vibrations on melt flows during detached Bridgman Crystal Growth
Journal of Crystal Growth, 2014Co-Authors: T. P. Lyubimova, D V Lyubimov, Andrey IvantsovAbstract:Abstract The paper deals with the numerical investigation of melt flows during germanium Crystal Growth by the Bridgman method under high frequency vibrations of the Crystal. According to the experimental setup the mathematical model takes into account the Crystal detachment from the crucible walls and the existence of technological channel in the crucible. The modeling is based on the average approach. The study has shown that the Crystal vibrations can substantially affect the melt flows. Near the resonance frequencies or when the vibration amplitude is high, a strong average flow generated in the technological channel could reach the Crystal-melt interface. Thus, varying the vibration parameters we can change the intensity and localization of the melt flows which should affect the interface shape and the detachment stability and therefore the grown Crystal properties.
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numerical investigation of heat and mass transfer during vertical Bridgman Crystal Growth under rotational vibrations
Journal of Crystal Growth, 2014Co-Authors: T. P. Lyubimova, Ya N ParshakovaAbstract:Abstract The paper deals with the numerical investigation of convective flows and heat and mass transfer in the directional solidification of binary melts in the presence of rotational vibrations of finite amplitude and frequency. The study is performed in the framework of the Boussinesq approximation and unsteady axisymmetric approach, taking into account the existence of the two-phase zone. The simulation is conducted for binary melt with low phase change temperature (succinonitrile with ethanol), using ANSYS Fluent package which realizes the finite volume method. The data on the temporal evolution of velocity, temperature and solute concentration fields in the melt and on the solute distribution in the grown Crystal with and without vibrations are obtained. It is demonstrated that the vibrations make strong stabilizing effect; they reduce the radial segregation and prevent the pit formation and solidification front breakdown, which leads to a substantial increase of grown Crystal homogeneity.
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effects of angular vibration on the flow segregation and interface morphology in vertical Bridgman Crystal Growth
International Journal of Heat and Mass Transfer, 2007Co-Authors: Z B Chen, Bernard Roux, T. P. Lyubimova, W T Hsu, C W LanAbstract:Abstract The effect of angular vibration on the flow, segregation, and interface morphology during vertical Bridgman Crystal Growth was investigated. Transparent experiments using SCN containing about 0.02 wt.% acetone were performed. To simulate the observed results, both direct numerical simulation (DNS) and Schlichting boundary layer approximation (SBLA) were considered in the computer model. The simulated morphological breakdown patterns, as a result of acetone accumulation (segregation), are consistent with the experimental observation. At high frequency with low amplitudes, both simulation approaches gave consistent results. However, care must be taken in using SBLA for low frequency vibration of several hertz.
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thermal solutal flows and segregation and their control by angular vibration in vertical Bridgman Crystal Growth
Chemical Engineering Science, 2006Co-Authors: Yu Cheng Liu, Bernard Roux, T. P. Lyubimova, C W LanAbstract:Abstract Thermal–solutal flows and their induced segregation and supercooling are important in the Growth of an alloy Crystal. For the vertical Bridgman Crystal Growth having a stabilized thermal profile, in addition to the thermal convection induced by radial thermal gradients, solute gradients can either induce or suppress the flow depending on the solute density. Such thermal–solutal flows significantly affect the segregation behavior, constitutional supercooling, and thus the morphological instability of the solidification front. A transparent Bridgman Growth of succinonitrile containing a lighter (acetone) or heavier (salol) solute was investigated. The evolution of the interface shape as well as morphological instability was visualized and was interpreted through computer simulation. To further control the flow and segregation, angular vibration was applied and its effects on the thermal–solutal flows and morphological instability were investigated.
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reversing radial segregation and suppressing morphological instability during Bridgman Crystal Growth by angular vibration
Journal of Crystal Growth, 2004Co-Authors: Z B Chen, Bernard Roux, T. P. Lyubimova, W T Hsu, C W LanAbstract:During vertical Bridgman Crystal Growth, local solute accumulation along the freezing interface due to buoyancy often causes radial non-uniformity and pit formation, which accelerate morphological instability. A novel approach by using angular vibration has been proposed. Through the visualization of the freezing interface during directional solidification of succinonitrile containing acetone, it was shown that angular vibration about the Growth axis was effective in reversing radial segregation and thus enhancing morphological stability. Simulation was conducted and good agreement was found.