Growth of Ribbon-Shaped Crystals
Ribbon-shaped crystals, also known as plate, platelets and sheet-type crystals, are usually composed of three or four crystal faces which differ from their length and width. Generally, they can easily be grown in two directions which lie in the two distinct planes of the material and the two faces of the material should be the same size. This type of crystal growth can be achieved through methods of epitaxy, liquid-phase deposition, electrochemical deposition, and thermal evaporation.
Epitaxy is a technique that enables the growth of crystalline layers on a substrate as an ordered extension of the substrate’s existing crystal structure. This can be achieved through the use of covalent assembly, in which a thin film material is deposited onto the substrate with a certain degree of lattice mismatch between the lattices of the substrate and the film. The film then grows until the energy of the mismatch is minimized, leading to a crystalline structure with a specific orientation. In terms of ribbon crystals, this type of growth is usually useful for producing thin films with a preferred orientation, such as in the direction of 110 or 100.
Liquid-phase deposition (LPD) is a technique used for the growth of crystals from solutions that can be used in many different environments and can yield different types of crystal shapes. By including dopants and other modifiers in the solution, one can influence the crystalline character of the product formed on the substrate. For example, one can modify the substrate’s surface to ensure that it is compatible with the desired crystal type, which is necessary for LPD to yield ribbon-shaped crystals.
Electrochemical deposition is another technique employed to grow ribbon-shaped crystals. In this method, a thin film is deposited on the substrate by chemically altering the substrates surface with an electric current. By controlling the electric current, the rate of crystal formation and the orientation of the crystals can be regulated. This method is often used to grow ribbons of three or four facets, as the electric current increases the electrical field which is necessary for the growth of the molecular layer in certain orientations.
The last method used to grow ribbon-shaped crystals is thermal evaporation. This form of crystal growth is based on the principle that materials evaporate from the source material when subjected to a certain temperature. The material is then deposited onto the substrate in form of thin films, allowing for the growth of ribbon-shaped crystals.
In conclusion, the growth of ribbon-shaped crystals has a significant range of applications and can be achieved by various methods, such as epitaxy, liquid-phase deposition, electrochemical deposition, and thermal evaporation. These techniques largely depend upon the properties of the substrate on which the crystals will be grown, and can be modified to ensure the desired growth of ribbon-shaped crystals with the desired orientation.
