Process for growing shaped single crystals

A process for growing shaped single crystals of refractory optically transparent metal compounds, comprising the steps of:

• (1) melting a starting stock of said refractory metal compound in an inert gas atmosphere under the effect of heat evolved by a heater;
• (2) fusing a seed in a zone of crystallization;
• (3) building-up a single crystal and pulling thereof from the zone of crystallization to a required length while continuously feeding a melt into the zone of crystallization through a capillary system of a shaping unit;
• and
• (4) varying the power of the heater after which the single crystal is cut-off from the melt and cooled, wherein prior to melting of the starting stock, a control particle of said starting stock is placed in the zone of crystallization, the power P of the heater is noted at the moment of fusing of said control particle, and melting of the starting stock is then effected at a heater power of (1.04-1.1)P, fusing of the seed is carried out at a power of the heater of (1.03-1.08)P, building-up of the single crystal at a power of (1.02-1.08)P, pulling of the single crystal from the crystallization zone at a power of (1.02-1.22)P and cooling of the single crystal is conducted at a rate of 20.degree.-30.degree. C./min. by lowering power of the heater, and upon reaching the single crystal temperature of 1,600.degree.-1,550.degree. C., the heater is switched-off.