Czochralskii Method:

Growth of single crystal. 

•Seed crystal is placed in contact with melt. 

•Melt is at a higher temperature than the melting point. 

•Seed is pulled out & the melt solidifies on the seed surface. 

•The grown crystal achieves the same lattice parameter as that of the seed. 

•During the process melt & seed crystals are rotated counterclockwise. 

USES: Due to this a uniform, rod-shaped single crystal is grown . 

•It is used for optical paths preparation for various spectroscope instruments 

•Used for synthesis semi-conducting materials like Si, Ge, Ga, As. 

•Used for preparation of neodymium dopped LASER Ca(NbO3)3 

Czochralski method (or) Pulling Technique: 

This method is widely used for growing semiconducting material crystals. 

The shape of the crystal is free from the constraint due to the shape of the crucible. In this method, the charge is melted and maintained at a temperature slightly above the melting point. 

The pulling rod is lowered to just touch the melt. Since the rod is at a lower temperature of melt occurs at the pointed tip of the pulling rod. 

The crystal is pulled slowly. The rate of pulling upon various factors like thermal conductivity, latent heat of fusion of charge, and rate of cooling of the pulling rod. The seed is rotated to keep the grow crystal uniform and cylindrical. 

Advantage:

1.This method is used to grow large single crystals. Thus it is used extensively in the semiconductor industry. 

2.There is no direct contact between the crucible walls and the crystal which helps to produce an unstressed single crystal. 

Disadvantage: 

In general, this method is not suitable for incongruently melting compounds and of course the need for a seed crystal of the same composition limits is used as a tool for exploratory synthetic research.