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Monocrystal
In materials science, a single crystal (or single-crystal solid or monocrystalline solid) is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no Grain boundary, grain boundaries. The absence of the crystallographic defect, defects associated with grain boundaries can give monocrystals unique properties, particularly mechanical, optical and electrical, which can also be anisotropic, depending on the type of crystallography, crystallographic structure. These properties, in addition to making some gems precious, are industrially used in technological applications, especially in optics and electronics. Because entropy, entropic effects favor the presence of some imperfections in the microstructure of solids, such as impurity, impurities, inhomogeneous strain and crystallographic defects such as dislocations, perfect single crystals of meaningful size are exceedingly rare in nature. The necessary laboratory condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Czochralski Process
The Czochralski method, also Czochralski technique or Czochralski process, is a method of crystal growth used to obtain single crystals (monocrystals) of semiconductors (e.g. silicon, germanium and gallium arsenide), metals (e.g. palladium, platinum, silver, gold), salts and synthetic gemstones. The method is named after Polish scientist Jan Czochralski, who invented the method in 1915 while investigating the crystallization rates of metals. He made this discovery by accident: instead of dipping his pen into his inkwell, he dipped it in molten tin, and drew a tin filament, which later proved to be a single crystal. The process remains economically important, as roughly 90% of all modern-day semiconductor devices use material derived from this method. The most important application may be the growth of large cylindrical ingots, or boules, of single crystal silicon used in the electronics industry to make semiconductor devices like integrated circuits. Other semiconductors, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallite
A crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials. Crystallites are also referred to as grains. Bacillite is a type of crystallite. It is rodlike with parallel Wikt:longulite , longulites. Structure The orientation of crystallites can be random with no preferred direction, called random Texture (chemistry), texture, or directed, possibly due to growth and processing conditions. While the structure of a single crystal is highly ordered and its crystal lattice, lattice is continuous and unbroken, amorphous solid, amorphous materials, such as glass and many polymers, are non-crystalline and do not display any structures, as their constituents are not arranged in an ordered manner. Polycrystalline structures and paracrystalline phases are in between these two extremes. Polycrystalline materials, or polycrystals, are solids that are composed of many crystallites of varying size and orientation. Most materials are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Vapor Deposition
Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (electronics), wafer (substrate) is exposed to one or more Volatility (chemistry), volatile wikt:precursor, precursors, which chemical reaction, react and/or chemical decomposition, decompose on the substrate surface to produce the desired deposit. Frequently, volatile by-products are also produced, which are removed by gas flow through the reaction chamber. Microfabrication processes widely use CVD to deposit materials in various forms, including: Single crystal, monocrystalline, polycrystalline, amorphous, and Epitaxy, epitaxial. These materials include: silicon (Silicon dioxide, dioxide, silicon carbide, carbide, silicon nitride, nitride, silicon oxynitride, oxynitride), carbon (carbon (fiber), fiber, carbon nanofibers, nanofibers, carbon nanot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anisotropic
Anisotropy () is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical property, physical or list of materials properties#Mechanical properties, mechanical properties when measured along different axes, e.g. absorbance, refractive index, electrical resistivity and conductivity, conductivity, and tensile strength. An example of anisotropy is light coming through a polarizer. Another is wood, which is easier to split along its wood grain, grain than across it because of the directional non-uniformity of the grain (the grain is the same in one direction, not all directions). Fields of interest Computer graphics In the field of computer graphics, an anisotropic surface changes in appearance as it rotates about its normal (geometry), geometric normal, as is the case with velvet. Anisotropic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallography
Crystallography is the branch of science devoted to the study of molecular and crystalline structure and properties. The word ''crystallography'' is derived from the Ancient Greek word (; "clear ice, rock-crystal"), and (; "to write"). In July 2012, the United Nations recognised the importance of the science of crystallography by proclaiming 2014 the International Year of Crystallography.UN announcement "International Year of Crystallography" iycr2014.org. 12 July 2012 Crystallography is a broad topic, and many of its subareas, such as X-ray crystallography, are themselves important scientific topics. Crystallography ranges from the fundamentals of crystal structure to the mathematics of Crystal system, crystal geometry, including those that are Aperiodic crystal, not periodic or quasi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kyropoulos Method
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.Dobrovinskaya, Elena R., Leonid A. Lytvynov, and Valerian Pishchik. Sapphire: material, manufacturing, applications. Springer Science & Business Media, 2009. History The method is named for , who proposed the technique in 1926 as a method to grow brittle alkali halide and alkali earth metal crystals for precision optics. The method was a response to the limited boule sizes attainable by the Czochralski and Verneuil methods at the time. The Kyropoulos method was applied to sapphire crystal growth in the 1970s in the Soviet Union. The method The feedstock is melted in a crucible. (For sapphire crystal growth, the feed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Telephone Laboratories
Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the company operates several laboratories in the United States and around the world. As a former subsidiary of the American Telephone and Telegraph Company (AT&T), Bell Labs and its researchers have been credited with the development of radio astronomy, the transistor, the laser, the photovoltaic cell, the charge-coupled device (CCD), information theory, the Unix operating system, and the programming languages B (programming language), B, C (programming language), C, C++, S (programming language), S, SNOBOL, AWK, AMPL, and others, throughout the 20th century. Eleven Nobel Prizes and five Turing Awards have been awarded for work completed at Bell Laboratories. Bell Labs had its origin in the complex corporate organization of the Bell System telepho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zone Melting
Zone melting (or zone refining, or floating-zone method, or floating-zone technique) is a group of similar methods of purifying crystals, in which a narrow region of a crystal is melted, and this molten zone is moved through the crystal. The molten region melts impure solid at its forward edge and leaves a wake of purer material solidified behind it as it moves through the ingot. The impurities concentrate in the melt, and are moved to one end of the ingot. Zone refining was invented by John Desmond Bernal and further developed by William G. PfannWilliam G. Pfann (1966) ''Zone Melting'', 2nd edition, John Wiley & Sons in Bell Labs as a method to prepare high-purity materials, mainly semiconductors, for manufacturing transistors. Its first commercial use was in germanium, refined to one atom of impurity per ten billion,”Zone melting”, entry in ''The World Book Encyclopedia'', Volume 21, W-X-Y-Z, 1973, page 501. but the process can be extended to virtually any solute–solvent sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recrystallization (chemistry)
Recrystallization is a broad class of List of purification methods in chemistry , chemical purification techniques characterized by the dissolution of an impure sample in a solvent or solvent mixture, followed by some change in conditions that encourages the formation of pure isolate as solid crystals. Recrystallization as a purification technique is driven by spontaneous process , spontaneous processes of molecular self-assembly , self-assembly that leverage the highly ordered (i.e. low-entropy) and periodic characteristics of a crystal's molecular structure to produce purification. Basic principles The driving force of this purification emerges from the difference in molecular interactions between the isolate and the impurities: if a molecule of the desired isolate interacts with any isolate crystal present, it is likely the molecule Deposition (chemistry) , deposits on the crystal's ordered surface and contributes to the crystal's growth; if a molecule of the impurity inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrothermal Synthesis
Hydrothermal synthesis includes the various techniques of synthesizing substances from high-temperature aqueous solutions at high pressures; also termed "hydrothermal method". The term "hydrothermal" is of geologic origin. Geochemists and mineralogists have studied hydrothermal phase equilibria since the beginning of the twentieth century. George W. Morey at the Carnegie Institution and later, Percy W. Bridgman at Harvard University did much of the work to lay the foundations necessary to containment of reactive media in the temperature and pressure range where most of the hydrothermal work is conducted. In the broadest definition, a process is considered hydrothermal if it involves water temperatures above and pressures above 1 atm. In the context of material science, hydrothermal synthesis focuses on the production of single crystal. Under high temperature > (300 °C) and pressure (> 100 atm), ordinarily insoluble minerals become soluble in water. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
