Model based optimization of some growth process parameters of a Nd:YVO4 cylindrical bar grown by edge-defined film-fed growth (EFG) method in the presence of the pressure

The purpose of this paper is to find those values of the radius r0e of the outer edge of the die, pulling rate v, melt temperature T0 at the meniscus basis and pressure p in the furnace, which assure the growth of a Nd:YVO4 monocrystal cylindrical bar with prescribed radius rf and for which the surface non-uniformity of the bar, due to small uncontrollable oscillations of v and T0, is minimum. Numerical results are given for a Nd:YVO4 cylindrical bar of 2.5 (mm) radius, grown in a furnace in which the vertical temperature gradient is k = 33 (K/mm) for four type of uncontrollable oscillations: O1 = (Δv = ±0.001 (mm/s) and ΔT = ±1 (K)), O2 = (Δv = ±0.01 (mm/s) and ΔT = ±10 (K)), O3 = (Δv = ±0.02 (mm/s) and ΔT = ±20 (K)), O4 = (Δv = ±0.001 (mm/s) and ΔT = ±30 (K)), respectively. For a smooth surface, the parameters r0e, v and T0 has to be chosen as follows: