Minimization of the surface non-uniformity of a Nd:YVO_4 cylindrical bar grown by edge-defined film-fed growth (EFG) method, when the pressure in the furnace changes

摘要

In this paper the dependence of the crystal radius on the pulling rate (v), melt temperature (T_0) at the meniscus basis, pressure in the furnace (p) and die radius (r_(0e)) is found. This dependence is used to show in which kind the effect of the variation of one of these parameters can be compensated by varying an other one. Those values of v, T_0, p and r_(0e) are determined for which the crystal radius variations due to small uncontrollable variations of v, T_0, p around some average values cause minimal surface non-uniformity. Numerical results are given for a Nd:YVO_4 cylindrical bar grown in a furnace in which the vertical temperature gradient is k= 33 K/mm.