A Novel System for Growth of Single Crystals from the Melt with an Innovative New Pulling Mechanism

This paper describes a crystal growth system employing novel concepts in fabrication of a high temperature furnace, thermocouples and a novel crystal pulling mechanism. This has reduced the costs substantially, without compromising the quality of grown crystals. The core of the furnace, a wooden cylindrical dummy had been prepared with equi-spaced helical groves with widths equaling the diameter of the heating wire on its outer surface machined by a lathe machine. The Kanthal heating wire was wound in the groves. It was covered with a thick layer of natural clay available locally. After the clay had dried up, an electric current was passed through the heating wire and the wooden frame was burnt out. A thick layer of the clay was applied on the inner and the outer surfaces. The furnace can operate at temperatures up to about 1000 °C. The temperature was measured with a chromel-alumel thermocouple prepared by an ingenious spot-welding technique established in the laboratory. The seed holder was hanged above the melt kept in the crucible with help of a float kept in a water container, which has a small tap at the bottom. When the tap is opened the float goes down and the seed assembly goes up. In this manner a quality pulling system, without any motor has been developed and reported here. It has been possible to grow good quality crystals of potassium chloride with excellent diameter control.