In situ observation method has been carried out to investigate the growth kinetics of salol from the melt.The temperature-dependence of growth rate of salol crystals in a supercooling range of 0 to 3°C for(102)an...In situ observation method has been carried out to investigate the growth kinetics of salol from the melt.The temperature-dependence of growth rate of salol crystals in a supercooling range of 0 to 3°C for(102)and(012)faces are studied.The lateral(two dimensional nucleation)–to-continuous growth transition has been obtained.The free energy of stepε,the radius of the critical nucleus r*,and the excess free energy of a critical nucleusΔG*are measured for(102)and(012)faces.展开更多
The micro-morphology of the interface transition from(0112)facet to freezing isotherm curve has been observed.In the centre of the interface(the high supercooling region), the morphology of(0112)facet shows characteri...The micro-morphology of the interface transition from(0112)facet to freezing isotherm curve has been observed.In the centre of the interface(the high supercooling region), the morphology of(0112)facet shows characteristics of terrace-step-kink structure.By reducing supercoolings the growth interface gradually turn to agreeing with the freezing isotherm curve.展开更多
The morphology of salol crystals in relation to supercooling has been studied by means of the in situ obseirvation method and the Kyropoulos technique;and Hartman-Perdok's PBC method was used to analyse the morpho...The morphology of salol crystals in relation to supercooling has been studied by means of the in situ obseirvation method and the Kyropoulos technique;and Hartman-Perdok's PBC method was used to analyse the morphology based on the relationship between crystal form and its structure.The experimental results of the morphology of salol crystals are compared with the theoretical calculations.展开更多
We have investigated experimentally and theoretically the thermocapillary convec tive flow phenomena in a loop-shaped Pt wire heater of KNbO_(3)(20wt.%)and Li_(2)B_(4)O_(7) solutions.Optical evaluations in connection ...We have investigated experimentally and theoretically the thermocapillary convec tive flow phenomena in a loop-shaped Pt wire heater of KNbO_(3)(20wt.%)and Li_(2)B_(4)O_(7) solutions.Optical evaluations in connection with thermocouple measure ments made it possible to get a new type of thermocapillary convective flow in the considered system.To study the kinematical behaviour of thermocapillary convec tion,we have measured the stream flow velocities.In a theoretical analysis,the flow velocity due to the thermocapillary effect alone was estimated by balancing the sur face tension forces by viscous forces.The velocity distribution in the solution near the margin of the heater was obtained,which is in agreement with the experimental result.……展开更多
The effect of a transverse magnetic field on the oscillatory thermocapillary con- vection in the NaBi(WO4)2 melt was studied by using the in-situ observation system. The oscillation was attenuated when the 60 mT magne...The effect of a transverse magnetic field on the oscillatory thermocapillary con- vection in the NaBi(WO4)2 melt was studied by using the in-situ observation system. The oscillation was attenuated when the 60 mT magnetic field was applied, as shown by the decrease in the amplitude and the frequency. Furthermore, the os- cillation under smaller temperature difference was stabilized after the magnetic field was applied. The magnetic effect could be due to the Lorentz force generated by the interaction between motional ions and the vertical magnetic field. The ionic conductivities were measured to demonstrate the effect of the magnetic field. The solid ionic electrical conductivity increases with the temperature rise, and the melt ionic electrical conductivity was measured to be about 2.0×10-4 -1cm-1. Experi- mental results manifest that the effect of the magnetic field on anions and cations in the melt makes the flow change to the direction normal to the applied field, so the flow is more orderly and the oscillation is suppressed.展开更多
文摘In situ observation method has been carried out to investigate the growth kinetics of salol from the melt.The temperature-dependence of growth rate of salol crystals in a supercooling range of 0 to 3°C for(102)and(012)faces are studied.The lateral(two dimensional nucleation)–to-continuous growth transition has been obtained.The free energy of stepε,the radius of the critical nucleus r*,and the excess free energy of a critical nucleusΔG*are measured for(102)and(012)faces.
基金supported by the Science Fund of the Chinese Academy of Sciences。
文摘The micro-morphology of the interface transition from(0112)facet to freezing isotherm curve has been observed.In the centre of the interface(the high supercooling region), the morphology of(0112)facet shows characteristics of terrace-step-kink structure.By reducing supercoolings the growth interface gradually turn to agreeing with the freezing isotherm curve.
文摘The morphology of salol crystals in relation to supercooling has been studied by means of the in situ obseirvation method and the Kyropoulos technique;and Hartman-Perdok's PBC method was used to analyse the morphology based on the relationship between crystal form and its structure.The experimental results of the morphology of salol crystals are compared with the theoretical calculations.
文摘We have investigated experimentally and theoretically the thermocapillary convec tive flow phenomena in a loop-shaped Pt wire heater of KNbO_(3)(20wt.%)and Li_(2)B_(4)O_(7) solutions.Optical evaluations in connection with thermocouple measure ments made it possible to get a new type of thermocapillary convective flow in the considered system.To study the kinematical behaviour of thermocapillary convec tion,we have measured the stream flow velocities.In a theoretical analysis,the flow velocity due to the thermocapillary effect alone was estimated by balancing the sur face tension forces by viscous forces.The velocity distribution in the solution near the margin of the heater was obtained,which is in agreement with the experimental result.……
基金the National Natural Science Foundation of China (Grant No. 50331040)the Innovation Funds from Shanghai Institute of Ceramics,Chinese Academy of Sciences (Grant No. SCX0623)
文摘The effect of a transverse magnetic field on the oscillatory thermocapillary con- vection in the NaBi(WO4)2 melt was studied by using the in-situ observation system. The oscillation was attenuated when the 60 mT magnetic field was applied, as shown by the decrease in the amplitude and the frequency. Furthermore, the os- cillation under smaller temperature difference was stabilized after the magnetic field was applied. The magnetic effect could be due to the Lorentz force generated by the interaction between motional ions and the vertical magnetic field. The ionic conductivities were measured to demonstrate the effect of the magnetic field. The solid ionic electrical conductivity increases with the temperature rise, and the melt ionic electrical conductivity was measured to be about 2.0×10-4 -1cm-1. Experi- mental results manifest that the effect of the magnetic field on anions and cations in the melt makes the flow change to the direction normal to the applied field, so the flow is more orderly and the oscillation is suppressed.
