Crystal growth velocity

Figure 12.4 Crystal growth velocity v as a function of excess vapor pressure (P — Pcq). Ideal sink curve pertains when all impinging adatoms are incorporated. Screw dislocation ledges curve pertains when ledges associated with screw dislocations limit the kinetics. Two-dimensional nucleation curve pertains when two-dimensional nucleation of ledges is rate-limiting.

Eq. (2.55) employs a linear crystal growth velocity (length/time) with Eq. (2.56) employs a mass rate of crystal growth (raass/area time). The constants in Eqs. (2.55) and (2.56) can be related to each other through the expression... 

Fig. 5.1. Crystal growth velocity v as a function of driving free-energy difference AGJ for various mechanisms of interface advance, (a) Two-dimensional nuclea-tion, (6) dislocation mechanism, (c) continuous advance of a rough interface.

Fig. 3.13. Nucleation and crystal growth velocity of parent glasses as a function of temperature...

In the following we consider the latter process. The crystal growth velocity can be obtained by calculating the difference between the attachment and detachment... 

The key property that makes phase change materials attractive for applications in nonvolatile memories is the fast crystallization which allows for a full crystallization in PCM devices on the time scale of 10-100 ns. The fact that both nucleation rate and crystal growth velocity are very large has stimulated direct simulations of the crystallization process by DFT-MD [13-16]. Simulations with up to 180-atom cell and periodic boundary conditions shed light on the atomistic mechanism of formation of the crystalline nucleus and on the role of four-membered rings as seeding structures for nucleation [13-16]. 

The Thomson-Spaepen approximation (15.6) was used for Afi with AH = 0.186 eV/atom and T = 1023K (exp. T = 998 K, [118]) for the NN potential obtained from thermodynamic integration in [68]. The Thomson-Spaepen approximation might appear as a crude approximation in view of DFT estimates of the temperature dependence of Cp for the crystalline and amorphous phases by Liu et al. (see Fig. 15.4 of [108]). However, in the temperature range 500-700K, the thermodynamic factor has actually a little effect on the crystal growth velocity compared to... 

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