Horia Alexandru 

University of Bucharest, Faculty of Physics, Bucharest-Magurele mg-11, Bucharest 76900, Romania


ADP crystal shows different kinetic mechanism of growth from solutions [1]. In "situ" macroscopic growth rates of prismatic and pyramidal faces were measured (+/- 0.01 mm accuracy) versus supersaturation (s). After seed regeneration, a transient regime of growth was found for the prismatic faces of ADP. Within a fresh grown layer, smaller than 1 mm, the growth efficiency decreases 3 to 6 times and it is 6 to 12 times higher than for the elementary dislocation [2]. Data compare well with interferometric measurements of Chernov et al [3]. Edge free energy on prismatic faces of ADP was estimated as 0.84 kT.
Macroscopic growth kinetic (at s <1%) of the pyramidal faces of ADP, measured in a long run, show also the decreasing of the growth efficiency (data not published yet). But this time, the effect has to be associated with the divergence of several dislocations from pyramidal, towards the prismatic faces. However, a surprising macroscopic effect was found. The "switching" of efficiency was found around s = 0.5%. A similar effect was found by laser interferometry in ref. [4], but at higher supersaturations s  3% when the dominating center of growth change the Burger’s vector from m=3 to m=2, or so. The microscopic parameter L/ma = 160-200, we have associated with the switching effect, is larger than the data from ref. [4]. Some other data related to KDP kinetic shall be presented.
References: [1] H.V.Alexandru, invited paper in conference “Crystallization and Electrocrystallization: Fundamentals and Applications”, May 2005, Varna, Bulgaria.
[2] H.V.Alexandru, S.Antohe, J.Cryst. Growth, 258 (2003) 149-157.
[3] Chernov et al, J.Cryst.Growth 74 (1986) 101.
[4] Vekilov et al J.Cryst.Growth 119 (1992) 248.


Related papers
  1. Kinetics and Growth Efficiency of Tetragonal Crystals

Presentation: oral at E-MRS Fall Meeting 2005, Symposium F, by Horia Alexandru
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-08-01 11:39
Revised:   2009-06-07 00:44