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A seed crystal is a small piece of single crystal or polycrystal material from which a large crystal of typically the same material is grown in a laboratory. Used to replicate material, the use of seed crystal to promote growth avoids the otherwise slow randomness of natural crystal growth, and allows manufacture on a scale suitable for industry.
Stockbarger's modification of the Bridgman technique allows for better control over the temperature gradient at the melt/crystal interface. When seed crystals are not employed as described above, polycrystalline ingots can be produced from a feedstock consisting of rods, chunks, or any irregularly shaped pieces once they are melted and allowed ...
Hydrothermal synthesis can be defined as a method of synthesis of single crystals that depends on the solubility of minerals in hot water under high pressure. The crystal growth is performed in an apparatus consisting of a steel pressure vessel called an autoclave, in which a nutrient is supplied along with water. A temperature gradient is ...
To achieve a moderate number of medium-sized crystals, a container which has a few scratches works best. Likewise, adding small previously made crystals, or seed crystals, to a crystal growing project will provide nucleating sites to the solution. The addition of only one seed crystal should result in a larger single crystal.
In the case of quartz crystals, the container is heated at 300 °C (which produces a pressure of 140 MPA). Without the mineralizer, higher temperatures are required to solubilize silica. Hydroxides and carbonates make silica more soluble by forming water-soluble sodium silicates. [4] Simplified equations can be represented as in the equation below
In the process, many small crystals formed initially (nuclei) slowly disappear, except for a few that grow larger, at the expense of the small crystals (crystal growth). The smaller crystals act as fuel for the growth of bigger crystals. Limiting Ostwald ripening is fundamental in modern technology for the solution synthesis of quantum dots. [17]
The Kyropoulos method, also known as the KY method or Kyropoulos technique, is a method of bulk crystal growth used to obtain single crystals.. The largest application of the Kyropoulos method is to grow large boules of single crystal sapphire used to produce substrates for the manufacture gallium nitride-based LEDs, and as a durable optical material.
A precisely oriented rod-mounted seed crystal is dipped into the molten silicon. The seed crystal's rod is slowly pulled upwards and rotated simultaneously. By precisely controlling the temperature gradients, rate of pulling and speed of rotation, it is possible to extract a large, single-crystal, cylindrical ingot from the melt.