Growth of single crystals lead molybdate by the Czochralski technique

An attachment for the automatic diameter control of single crystals grown from the melt by the Czochralski technique is designed, built and tested. The diameter controller is implemented on a digital computer, which uses the weight of the crucible plus melt as the signal input to a proportional-integral-differential control algorithm. The computer modulates the furnace temperature to effect variations in crystal diameter. The success of this control set-up is demonstrated by growing parallel-sided single crystals of both copper and silver. The diameter controller is used during the growth of single crystals of lead molybdate. For this material the interaction between rotation rate, melt convective flow regime, melt-solid interface shape and crucible weight signal is thought to complicate diameter control.