Single crystals are materials in which the entire sample has a continuous and unbroken crystal lattice to the edges of the sample with no grain boundaries. The lack of defects associated with grain boundaries can impart unique properties to single crystals, particularly mechanical, optical and electrical properties, which can also be anisotropic, depending on the type of crystal structure. In addition to making them valuable in certain gems, these properties are also used industrially for technical applications, particularly in the fields of optics and electronics.
Semi-conducting: Single crystal silicon is used to make semiconductors. At the quantum scale of microprocessor, the presence of grain boundaries will have a major impact on the function of field effect transistors by changing the local electrical characteristics. As a result, microprocessor manufacturers have invested heavily in single crystal silicon. Single crystal silicon consists of silicon, in which the crystal lattice of the entire solid is continuous, unbroken to its edges, and does not have any grain boundaries. Due to its semiconducting properties, single crystal silicon may be the most important technological material in the past few decades, because its availability at affordable cost is crucial for the development of electronic devices.
Electrical conductor: The single crystal provides a means to understand and possibly achieve the ultimate performance of the metallic conductor. Among all metallic elements, silver and copper have the best conductivity at room temperature. Conductivity of commercial conductors is usually expressed relative to the International Annealed Copper Standard. Single crystal copper does have better conductivity than polycrystalline copper. Single crystal copper not only can become a better conductor than polycrystalline silver, but can even exceed single crystal silver in conductivity with specified heating and pressure treatment.
Optics: In the laboratory, single crystal calcium fluoride is commonly used as a window material for infrared and ultraviolet wavelengths because it is transparent in these regions and exhibits minimal refractive index changes with wavelength. Synthesized calcium fluoride crystals are used in the production of lenses to aid achromatic design and reduce light dispersion. As an infrared optical material, calcium fluoride dispersion is also widely available. In the telescope, fluorite elements can help to obtain high-resolution images of astronomical objects at high magnification.