Crystals and amorphous substances are different forms of solid matter, and there are obvious differences in their structure and properties.
Crystals are solid substances formed by the arrangement of atoms or molecules according to a certain law, and their internal structure has a three-dimensional periodicity. Crystals can be divided into seven major crystal systems according to the periodicity of their internal structure, each crystal system is divided into a number of crystal families, and each crystal family is divided into a number of crystal planes. The three most common space structures in crystals are tetrahedral, octahedral, and pentahedral.
Amorphous crystals are solid substances whose internal atomic or molecular arrangements are not three-dimensionally periodic. The internal structure of an amorphous body is characterized by an irregular, disordered arrangement of atoms or molecules, with no apparent spatial periodicity. Amorphous bodies exhibit isotropy in their physical properties, i.e., the physical properties measured along different directions are essentially the same.
Compared with crystals, amorphous bodies have a higher degree of disorder in their internal structure, resulting in superior physical and chemical properties. In the field of materials science, amorphous materials have a wide range of applications, such as glass and plastics are amorphous materials.
There is also a special kind of crystal - polycrystal. Polycrystals are formed by many small crystals gathered together in a disorderly manner, and their internal structure also has three-dimensional periodicity, but unlike single crystals. The physical and chemical properties of polycrystals are usually similar to those of single crystals, but in terms of mechanical properties, polycrystals tend to have better toughness and ductility.
Crystal uses:
1, optical equipment: many optical equipment and optical components are manufactured using the optical properties of crystals. For example, quartz crystals are the main material for manufacturing optical prisms, optical lenses and optical fibers. Some special crystals, such as laser crystals, can be used to make lasers, such as xenon lamps and diode lasers.
2, electronic products: crystals are key components in the manufacture of electronic products. For example, quartz crystal oscillators are widely used in all kinds of electronic products, such as clocks, radios, televisions, cell phones, etc., for generating stable frequencies. Meanwhile, transistors are the basic components in modern electronic devices, such as amplifiers, voltage regulators and so on.
3, sensors: many sensors utilize the sensitivity and conversion ability of crystals to specific physical quantities, and convert physical quantities into electrical signals. For example, quartz pressure sensors can measure pressure and temperature, while optical crystals can convert chemical or biological substances into electrical signals.
4, building materials: some crystals have high strength and durability, and can be used as building materials. For example, quartz glass can be used to make windows, mirrors and so on.
5. Medical and biological applications: Some crystals are biologically active and can be used for medical and biological applications. For example, calcium phosphate bone cement is a bioactive material that can be used for bone and dental treatments.