Crystalline Deposition
Crystalline Deposition - Related Videos
01:21
Polymer Classification: Crystallinity
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2023
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains. Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
09:45
Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition
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Cited by 3 •
2016
This work details the procedures for the growth and characterization of crystalline SrTiO3 directly on germanium substrates by atomic layer deposition. The procedure illustrates the ability of an all-chemical growth method to integrate oxides monolithically onto semiconductors for metal-oxide semiconductor devices.
11:17
Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction
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Cited by 107 •
2016
A novel methodology is presented to synthesize and program main-chain liquid-crystalline elastomers using commercially available starting monomers. A wide range of thermomechanical properties was tailored by adjusting the amount of crosslinker, while the actuation performance was dependent on the amount of applied strain during programming.
02:33
Phase Transitions: Sublimation and Deposition
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2020
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
12:04
Microfluidic Preparation of Liquid Crystalline Elastomer Actuators
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Cited by 3 •
2018
This article describes the microfluidic process and parameters to prepare actuating particles from liquid crystalline elastomers. This process allows the preparation of actuating particles and the variation of their size and shape (from oblate to strongly prolate, core-shell, and Janus morphologies) as well as the magnitude of actuation.
FAQs
The process separates two stages: nucleation creates initial stable crystal embryos, while crystal growth enlarges them as particles or molecules attach to energetically favorable sites. Supersaturation provides the driving condition for both stages, but their relative balance affects the final structure. Favoring many nucleation events can produce smaller crystals, whereas growth of fewer nuclei can yield larger deposits.
Temperature, concentration, solvent composition, pressure, and substrate conditions act as coupled control variables. They influence when the chemical system becomes unstable enough to initiate deposition and how efficiently material subsequently attaches. Adjusting these parameters therefore helps regulate crystal size, orientation, purity, and coating thickness. Changing one condition may alter several outcomes at once.
Surface deposition is governed partly by substrate conditions, because the surface supplies energetically favorable sites for attachment. These conditions can influence crystal orientation and coating thickness, while deposition within a material is controlled by the surrounding internal environment. This distinction helps chemists choose whether to target a surface coating or an internally formed crystalline region.
First identify whether material will be supplied from solution, vapor, or melt, then establish conditions that create sufficient supersaturation or another instability. Next, provide a suitable surface or material environment for nucleation and allow crystal growth while controlling temperature, concentration, solvent composition, pressure, and substrate conditions. The resulting deposit can then be evaluated for size, orientation, purity, and thickness.
Applications span both separation and materials research. Controlled crystalline deposition can contribute to purification, thin-film fabrication, materials synthesis, and preparation of functional surfaces. The relevant target differs by use: purification emphasizes composition, while fabrication and surface preparation emphasize structural control, crystal orientation, and coating thickness.
Researchers can judge the outcome by examining the properties that deposition is intended to control: composition, crystal size, orientation, purity, and coating thickness. In chemistry, these observations connect process conditions with the resulting material structure and properties. Comparing outcomes after changing temperature, concentration, solvent composition, pressure, or substrate conditions reveals which variables most strongly affect preparation.