Numerical modeling of diffusive physical vapor transport in cylindrical ampoules

Sublimation growth of titanium nitride crystals

“…However, as the transport of growth species from source to growing surface is often the rate limiting step in vapor crystal growth [22], equilibrium can be assumed at the surfaces of the source and seed. So for reaction (1):…”

Crystal Growth from the Vapour Phase

“…When the temperature dependence of the vapour density and diffusion coefficient is neglected, the molar concentration C A of the vapour species A changes along the distance x from the source as [6]: (22) The concentration distribution is shown in normalized form in Fig. 6.…”

“…Reference [6] introduces the Peclet number as the figure of merit of the convective flux relative to the diffusive flux, Le. :…”

“…On the basis of the existing theoretical models [3][4][5][6] one can conclude that these low growth rates are to a large degree the result of the gaseous impurities which reduce the mass flow through diffusion particularly in closed containers. Another importa.nt feature is the disturbance of the compositional perfection of the crystals by convective instabilities of the vapour phase caused by gravity.…”

Importance of convection during physical vapor transport of Hg2Cl2in the presence of Kr under environments of high gravitational accelerations

“…Until now many theoretical studies and quantitative experiments on transport phenomena in PVT have been extensively investigated. Most important theoretical works were achieved by Rosenberger et al [1][2][3][4][5][6] and, recently extended for transition to chaos flow fields in specialty materials of mercurous chloride in applications of microgravity experiments by Duval [7][8][9][10][11][12]. They have addressed the underlying phenomena in the PVT processes on the relative importance and influencing parameters of diffusion-advection, thermal and/or solutal convection on mass transport.…”