Czochralski’s discovery

In 1916 Jan Czochralski invented a method for measuring the crystallization velocity of metals. His paper was published in 1918 in Zeitschriftfur physikalische Chemie.. In this paper he recognized that the rate of withdrawal must be strictly equated to the crystallization velocity, this being different for different metals. The wires obtained in this way had diameters of about a millimeter and lengths up to 190 mm. The most important result was that the wires were single crystals! This new technique was described in several other papers from 1917 to 1924.

Czochralski’s invention was discovered essentially by accident. As the story goes, the young Czochralski, then chief of AEG’s metals laboratory in Berlin, was studying the crystallization of metals. A crucible containing molten tin was left on his table for slow cooling and crystallization. Czochralski was preparing his notes on the experiments carried out during the day when at some point, lost in thought, he dipped his pen into this crucible instead of inkwell placed nearby the crucible. He withdrew it quickly and saw a thin thread of solidified metal hanging at the tip of the nib. The discovery was made! He had generated a phenomenon never occurring in Nature – crystallization by pulling from the surface of a melt. However, careful observation of this accidental process provided a discovery of great importance and we should admire the creative perceptiveness of Czochralski. Accident, it is said, happens to the prepared mind. Later, the nib slot, in which crystallization was initiated, was re-placed by a special narrow capillary and later by a seed crystal of the material to be grown.