What is a single crystal?
A single crystal is a regular and periodic arrangement of particles inside a crystal in three-dimensional space. The entire lattice of single crystals is continuous, and single crystals have important industrial applications. Ideal single crystals of a certain size are extremely rare in nature and difficult to produce in the laboratory due to entropy effects that lead to non-idealities in the solid microstructure, such as impurities, inhomogeneous strain, and crystal defects. Common single crystals contain aluminum oxide, niobium, and palladium.
What are the preparation methods of single crystal?
Single crystal g rowth preparation methods can be roughly divided into the following methods:
1. Volatility method
Principle: The volatilization method relies on the continuous volatilization of the solution to make the solution from unsaturated to saturated and supersaturated.
Condition: The solid can be dissolved in relatively volatile organic solvents.
2. Diffusion method
Principle: Diffusion method utilizes two organic solvents that are completely miscible with a large difference in boiling point. The solid is easily soluble in high boiling point solvents, but hardly soluble or insoluble in low boiling point solvents. In a sealed container, the low-boiling-point solvent is volatilized into the high-boiling-point solvent to reduce the solubility of the solid, thereby precipitating crystal nuclei and growing into a single crystal. Generally, low-volatility solvents are selected, such as DMF, DMSO, glycerol, etc.
Conditions: Solids have relatively high or high solubility in less volatile solvents, and are insoluble or poorly soluble in volatile solvents. Experience: The more soluble the solid is in a less volatile solvent, the better. Solids must be saturated or nearly supersaturated in high boiling point solvents.
Method: Heat and dissolve the solid in a high-boiling-point solvent, close to saturation, place it in a sealed container, put a volatile solvent in the sealed container, seal it well, and let it stand for cultivation.
3. Temperature difference method
Principle: Utilize the solubility of a solid in an organic solvent, which changes greatly with the change of temperature, so that it reaches saturation or close to saturation at high temperature, and then slowly cools to precipitate crystal nucleus and grow into a single crystal. Generally, water, DMF, DMSO, and especially ionic liquids are suitable for this method.
Condition: Solubility varies greatly with temperature.
4. Contact method
Principle: If the complex is easily synthesized from two or more species, the selectivity is high and the formed complex is difficult to find a solvent to dissolve, then the raw materials can form a crystal nucleus at the contact point, and then grow to form a single crystal.
Method: 1. Use a U-shaped tube, and agar can be used to reduce the ion diffusion rate. 2. Slowly add or dilute the solution. 3. Raise the temperature slowly (applicable to systems with temperature requirements).
What are the applications of single crystal?
1. Single crystal in semiconductor field
Single crystals are the most widely used in the field of semiconductors. Single crystal materials can be made into various semiconductor components such as chips and control circuits, and are widely used in integrated circuits, optoelectronic devices, power devices and other fields. The application of single crystal is closely related to the continuous development of semiconductor electronic technology, which can make the circuit miniaturized, high-speed and intelligent, and improve the performance and quality of semiconductor devices.
2. Single crystal in optoelectronic field
The application of single crystal in optoelectronic field is also very important. Single crystal materials have good optoelectronic properties and transparency, and can be made into various optoelectronic devices, such as solar cells, LEDs, lasers, X-ray detectors, etc. The wide application of single crystal has made optoelectronic technology widely promoted and applied in high-tech fields such as communication, electronics, and information transmission.
3. Single crystal in the medical field
Single crystal is also widely used in the medical field. Single crystal materials have good biocompatibility and physical properties, and are widely used in medical devices and artificial organs. For example, medical devices such as artificial heart valves, vascular stents, dialyzers, and drug micropumps all use single crystal materials, making important contributions to the improvement of medical technology and the improvement of human life and health.
