“diffusion”的概念、定义、翻译、参考文献-科学参考

diffusion

Physics

1. The process by which different substances mix as a result of the random motions of their component atoms, molecules, and ions. In gases, all the components are perfectly miscible with each other and mixing ultimately becomes nearly uniform, though slightly affected by gravity (see also Graham’s law). The diffusion of a solute through a solvent to produce a solution of uniform concentration is slower, but otherwise very similar to the process of gaseous diffusion. In solids, however, diffusion occurs very slowly at normal temperatures.

2. The scattering of a beam of light by reflection at a rough surface or by transmission through a translucent (rather than transparent) medium, such as frosted glass.

3. The passage of elementary particles through matter when there is a high probability of scattering and a low probability of capture.

Chemistry

1. The process by which different substances mix as a result of the random motions of their component atoms, molecules, and ions. In gases, all the components are perfectly miscible with each other and mixing ultimately becomes nearly uniform, though slightly affected by gravity (see also Graham’s law). The diffusion of a solute through a solvent to produce a solution of uniform concentration is slower, but otherwise very similar to the process of gaseous diffusion. In solids, diffusion occurs very slowly at normal temperatures. See also Fick’s law.
2. The passage of elementary particles through matter when there is a high probability of scattering and a low probability of capture.

Chemical Engineering

The process of movement in which molecules of one substance move and penetrate other substances. In a mixture of gases, the rate of diffusion of one gas into another is inversely proportional to the square root of its densities (see graham’s law). In liquids, the diffusion of a solute through a solvent to produce a solution of uniform concentration is slower. Diffusion in solids occurs much more slowly.

Electronics and Electrical Engineering

1. The movement of charge carriers in a semiconductor. See Fick’s law.
2. The process of introducing selected impurity atoms into designated areas of a semiconductor in order to modify the properties of that area. The semiconductor is heated to a predetermined temperature in a gaseous atmosphere of the desired impurity. Impurity atoms that condense on the surface diffuse into the semiconductor material in both the vertical and horizontal directions. The numbers of impurity atoms and distance travelled at any given temperature is well-defined according to Fick’s law. The interface between two different conductivity regions within a semiconductor is known as a diffused junction.
Early diffused devices were formed by performing nonselective diffusions over the entire semiconductor surface; any unwanted regions of the semiconductor were etched away (as in mesa transistors) and the junctions were formed below the surface and parallel to it. Modern techniques use the planar process of selective diffusion into well-defined areas of semiconductor. The edge of the junction is perpendicular to the surface and the device may be formed along the surface of the material.
Double diffusion is a method of forming diffused junctions in which successive diffusions of different impurity types are made into the same well-defined region of semiconductor. The temperature and diffusion time are adjusted to produce the desired impurity concentration. This technique is used if very precise distances between junctions are required, as in DMOS circuits, since the geometry is defined by the diffusion process itself and errors caused by misalignment of successive photographic masks are eliminated.

Biology

The random movement of particles (e.g. molecules or ions) from an area of high concentration to an area of low concentration until an even distribution of particles (i.e. uniform concentration) is obtained. Small molecules and ions (such as oxygen and Na⁺) can diffuse across a plasma membrane.

Geology and Earth Sciences

1. Movement of molecules or ions from a region of higher to one of lower solute concentration as a result of their random thermal movement. For example, ions diffuse through a solution or melt towards growing crystals as their incorporation into the solid phase reduces their concentration in the immediately adjacent liquid.
2. (in crystals) (a) Self diffusion involves the movement of a unit of a given composition through a crystal lattice of the same composition. (b) Volume diffusion, the movement of atoms or ions through the crystal lattice. It includes simple self diffusion and more complex situations where ions of a certain species migrate through a lattice containing a variety of ions of different sizes or charges and in various configurations. Self diffusion leads only to change in shape or texture, volume diffusion leads to changes in composition.

Geography

The widespread dispersal of an innovation from a centre or centres. T. Hägerstrand’s model of diffusion (1968) implies the existence of a mean information field which regulates the flows of information around a regional system; flows that are moderated by barriers which can obstruct the evolution of information into innovation. ‘All the basic ideas that have come to be associated with diffusion research can be found in Lawrence Brown, 1981’ (Lutz (2006) PHG 30, 4).
‘To the extent that a high proportion of personal contacts are local, the diffusion of information must also be spatially constrained: the further people are from early adopters the later they are likely to be to adopt the innovation. To the extent that people’s non-local contacts are hierarchical (more likely to be with people in big cities than in small), the diffusion of information must also be hierarchically constrained: the lower down the urban hierarchy people live, the later they are likely to be to adopt the innovation…the diffusion of innovations reflects supplier behaviour as well as adopter behaviour’ (Webber (2006) PHG 30, 4). See Belhedi (2007) Cybergeo 372 and E. Rogers (2003).

单词	diffusion
释义	diffusion Physics 1. The process by which different substances mix as a result of the random motions of their component atoms, molecules, and ions. In gases, all the components are perfectly miscible with each other and mixing ultimately becomes nearly uniform, though slightly affected by gravity (see also Graham’s law). The diffusion of a solute through a solvent to produce a solution of uniform concentration is slower, but otherwise very similar to the process of gaseous diffusion. In solids, however, diffusion occurs very slowly at normal temperatures. 2. The scattering of a beam of light by reflection at a rough surface or by transmission through a translucent (rather than transparent) medium, such as frosted glass. 3. The passage of elementary particles through matter when there is a high probability of scattering and a low probability of capture. Chemistry 1. The process by which different substances mix as a result of the random motions of their component atoms, molecules, and ions. In gases, all the components are perfectly miscible with each other and mixing ultimately becomes nearly uniform, though slightly affected by gravity (see also Graham’s law). The diffusion of a solute through a solvent to produce a solution of uniform concentration is slower, but otherwise very similar to the process of gaseous diffusion. In solids, diffusion occurs very slowly at normal temperatures. See also Fick’s law. 2. The passage of elementary particles through matter when there is a high probability of scattering and a low probability of capture. Chemical Engineering The process of movement in which molecules of one substance move and penetrate other substances. In a mixture of gases, the rate of diffusion of one gas into another is inversely proportional to the square root of its densities (see graham’s law). In liquids, the diffusion of a solute through a solvent to produce a solution of uniform concentration is slower. Diffusion in solids occurs much more slowly. Electronics and Electrical Engineering 1. The movement of charge carriers in a semiconductor. See Fick’s law. 2. The process of introducing selected impurity atoms into designated areas of a semiconductor in order to modify the properties of that area. The semiconductor is heated to a predetermined temperature in a gaseous atmosphere of the desired impurity. Impurity atoms that condense on the surface diffuse into the semiconductor material in both the vertical and horizontal directions. The numbers of impurity atoms and distance travelled at any given temperature is well-defined according to Fick’s law. The interface between two different conductivity regions within a semiconductor is known as a diffused junction. Early diffused devices were formed by performing nonselective diffusions over the entire semiconductor surface; any unwanted regions of the semiconductor were etched away (as in mesa transistors) and the junctions were formed below the surface and parallel to it. Modern techniques use the planar process of selective diffusion into well-defined areas of semiconductor. The edge of the junction is perpendicular to the surface and the device may be formed along the surface of the material. Double diffusion is a method of forming diffused junctions in which successive diffusions of different impurity types are made into the same well-defined region of semiconductor. The temperature and diffusion time are adjusted to produce the desired impurity concentration. This technique is used if very precise distances between junctions are required, as in DMOS circuits, since the geometry is defined by the diffusion process itself and errors caused by misalignment of successive photographic masks are eliminated. Biology The random movement of particles (e.g. molecules or ions) from an area of high concentration to an area of low concentration until an even distribution of particles (i.e. uniform concentration) is obtained. Small molecules and ions (such as oxygen and Na⁺) can diffuse across a plasma membrane. Geology and Earth Sciences 1. Movement of molecules or ions from a region of higher to one of lower solute concentration as a result of their random thermal movement. For example, ions diffuse through a solution or melt towards growing crystals as their incorporation into the solid phase reduces their concentration in the immediately adjacent liquid. 2. (in crystals) (a) Self diffusion involves the movement of a unit of a given composition through a crystal lattice of the same composition. (b) Volume diffusion, the movement of atoms or ions through the crystal lattice. It includes simple self diffusion and more complex situations where ions of a certain species migrate through a lattice containing a variety of ions of different sizes or charges and in various configurations. Self diffusion leads only to change in shape or texture, volume diffusion leads to changes in composition. Geography The widespread dispersal of an innovation from a centre or centres. T. Hägerstrand’s model of diffusion (1968) implies the existence of a mean information field which regulates the flows of information around a regional system; flows that are moderated by barriers which can obstruct the evolution of information into innovation. ‘All the basic ideas that have come to be associated with diffusion research can be found in Lawrence Brown, 1981’ (Lutz (2006) PHG 30, 4). ‘To the extent that a high proportion of personal contacts are local, the diffusion of information must also be spatially constrained: the further people are from early adopters the later they are likely to be to adopt the innovation. To the extent that people’s non-local contacts are hierarchical (more likely to be with people in big cities than in small), the diffusion of information must also be hierarchically constrained: the lower down the urban hierarchy people live, the later they are likely to be to adopt the innovation…the diffusion of innovations reflects supplier behaviour as well as adopter behaviour’ (Webber (2006) PHG 30, 4). See Belhedi (2007) Cybergeo 372 and E. Rogers (2003).
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