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Deposition is the phase transition in which gas transforms into solid without passing through the liquid phase. Deposition is a thermodynamic process . The reverse of deposition is sublimation and hence sometimes deposition is called desublimation .
In chemistry, deposition occurs when molecules settle out of a solution. Deposition can be defined as the process of direct transition of a substance from its gaseous form, on cooling, into a solid state without passing through the intermediate liquid state. [1] Deposition can be viewed as a reverse process to dissolution or particle re ...
Alternatively, when the reaction of the solid and the transport agent is endothermic, the solid is transported from a hot zone to a cooler one. For example: Fe 2 O 3 + 6 HCl ⇌ Fe 2 Cl 6 + 3 H 2 O ΔH rxn > 0 (endothermic) The sample of iron(III) oxide is maintained at 1000 °C, and the product is grown at 750 °C. HCl is the transport agent.
The following equation is an example, where M represents the given metal: MCO 3 → MO + CO 2. A specific example is that involving calcium carbonate: CaCO 3 → CaO + CO 2. Metal chlorates also decompose when heated. In this type of decomposition reaction, a metal chloride and oxygen gas are the products. Here, again, M represents the metal:
Atomic layer deposition (ALD) is a thin-film deposition technique based on the sequential use of a gas-phase chemical process; it is a subclass of chemical vapour deposition. The majority of ALD reactions use two chemicals called precursors (also called "reactants").
Strictly speaking the above equation holds also for systems with chemical reactions if the terms in the balance equation are taken to refer to total mass, i.e. the sum of all the chemical species of the system. In the absence of a chemical reaction the amount of any chemical species flowing in and out will be the same; this gives rise to an ...
Physical vapor deposition (PVD), sometimes called physical vapor transport (PVT), describes a variety of vacuum deposition methods which can be used to produce thin films and coatings on substrates including metals, ceramics, glass, and polymers. PVD is characterized by a process in which the material transitions from a condensed phase to a ...
Particle deposition is the spontaneous attachment of particles to surfaces. The particles in question are normally colloidal particles , while the surfaces involved may be planar, curved, or may represent particles much larger in size than the depositing ones (e.g., sand grains).