Deposition (chemistry)
Encyclopedia
In chemistry
, deposition is the settling of particles (atom
s or molecule
s) or sediment
from a solution
, suspension
and mixture or vapor onto a pre-existing surface
. Deposition generally results in growth of new phase
and is of fundamental importance in a large number of scientific disciplines and practical applications, the most obvious ones being in geology, meteorology and chemical engineering.
The term is also widely used in earth science
to describe the same process in a geological sense. Deposition of particles is an aggradational process — one that builds a landform
— as opposed to a degradational process that erodes or reduces the size of a landform. For example, a river
mouth delta
is formed by deposition of sediment carried by the stream as the river current diminishes upon encountering the sea
.
Deposition can be viewed as a process reverse to sublimation, dissolution
, or particle re-entrainment.
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, deposition is the settling of particles (atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s or molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s) or sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
from a solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
, suspension
Suspension (chemistry)
In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. The internal phase is dispersed throughout the external phase through mechanical agitation, with the use of certain...
and mixture or vapor onto a pre-existing surface
Surface
In mathematics, specifically in topology, a surface is a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3 — for example, the surface of a ball...
. Deposition generally results in growth of new phase
Phase (matter)
In the physical sciences, a phase is a region of space , throughout which all physical properties of a material are essentially uniform. Examples of physical properties include density, index of refraction, and chemical composition...
and is of fundamental importance in a large number of scientific disciplines and practical applications, the most obvious ones being in geology, meteorology and chemical engineering.
The term is also widely used in earth science
Earth science
Earth science is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, the Earth being the only known life-bearing planet. There are both reductionist and holistic approaches to Earth sciences...
to describe the same process in a geological sense. Deposition of particles is an aggradational process — one that builds a landform
Landform
A landform or physical feature in the earth sciences and geology sub-fields, comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography...
— as opposed to a degradational process that erodes or reduces the size of a landform. For example, a river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
mouth delta
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...
is formed by deposition of sediment carried by the stream as the river current diminishes upon encountering the sea
Sea
A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...
.
Deposition can be viewed as a process reverse to sublimation, dissolution
Dissolution (chemistry)
Dissolution is the process by which a solid, liquid or gas forms a solution in a solvent. In solids this can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent. For liquids and gases, the molecules must be compatible...
, or particle re-entrainment.
See also
- Atomic layer depositionAtomic layer depositionAtomic layer deposition is a thin film deposition technique that is based on the sequential use of a gas phase chemical process. The majority of ALD reactions use two chemicals, typically called precursors. These precursors react with a surface one-at-a-time in a sequential manner...
- Chemical vapor depositionChemical vapor depositionChemical vapor deposition is a chemical process used to produce high-purity, high-performance solid materials. The process is often used in the semiconductor industry to produce thin films. In a typical CVD process, the wafer is exposed to one or more volatile precursors, which react and/or...
- Deposition (physics)Deposition (physics)Deposition is a process in which gas transforms into solid . The reverse of deposition is sublimation.One example of deposition is the process by which, in sub-freezing air, water vapor changes directly to ice without first becoming a liquid...
- FoulingFoulingFouling refers to the accumulation of unwanted material on solid surfaces, most often in an aquatic environment. The fouling material can consist of either living organisms or a non-living substance...
- Physical vapor depositionPhysical vapor depositionPhysical vapor deposition is a variety of vacuum deposition and is a general term used to describe any of a variety of methods to deposit thin films by the condensation of a vaporized form of the desired film material onto various workpiece surfaces...
- Thin-film deposition