Lead bromide crystal growth from the melt and characterization: the effects of nonlinear thermal boundary conditions on convection during physical vapor crystal growth of mercurous bromide
1
조회
0
다운로드
3
인용
0
참고문헌
초록
Abstract
We investigate the effects of solutal convection on the crystal growth rate in a horizontal configuration for diffusive-convection conditions and purely diffusion conditions achievable in a low gravity environment for a nonlinear thermal gradient. It is concluded that the solutally-driven convection due to the disparity in the molecular weights of the component A (Hg2Br2) and B (CO) is stronger than thermally-driven convection for both the nonlinear and the linear thermal profiles, corresponding to Grt = 8.5?03, Grs = 1.05?05. For both solutal and thermal convection processes, the growth rates for the linear thermal profile (conducting walls) are greater than for the nonlinear case. With the temperature humps, there are found to be observed in undersaturation for diffusive-convection processes ranging from DAB = 0.087 to 0.87. For the vertical configurations, the diffusion mode is so much dominated that the growth rate and interfacial distribution is nearly regardless of the gravitational accelerations. Also, the diffusion mode is predominant over the convection for the gravity levels less than 0.1 g0 for the horizontally oriented configuration.
참고문헌 (10)
- N.B. Singh et al, "Growth and characterization of mer-curous halide crystals", pp.155~ (1994)
- F. Rosenberger, "Viohl and N. Buchan,Physical vapor transport revised", 171, pp.270~ (1997)
- F. Rosenberger, "Fluid dynamics in crystal growth fromvapors", pp.3~ (1980)
- N.B. Singh, "Evalua-tion of transport conditions during PVT", pp.41~ (1989)
- B.L. Markham, "Numerical modeling of difusive-convective physicalvapor transport in cylindrical vertical ampoules", pp.426~ (1981)
- Walter M.B. Duval, "Convection in the physical vaportransport process-- I", pp.188~ (1994)
- Walter M.B. Duval, "Transition to chaos in the physicaltransport process--I the Proceding of the ASME--WAM Winter Anual meting Fluid mechanics phe-nomena in microgravity", pp.~174 175 (1993)
- A. Nadarajah, "Efectsof buoyancy-driven flow and thermal boundary condi-tions on physical vapor transport", pp.49~ (1992)
- H. Zhou, "Physical vapor transport of zinc-teluride by dissocia-tive sublimation", 167, pp.534~ (1996)
- H. Opermann, "Chemical aspects of Hg2X2-decomposi-tion Pro-ceedings of the 2nd Intl symposium on univalent mercuryhalides"