Introduce amorphous materials

Amorphous materials are also called amorphous or glassy materials, which are a large class of rigid solids with high hardness and high viscosity coefficients comparable to crystalline substances (usually 10 poise, that is, 10 Pa·s or more, is 10 times the viscosity coefficient of a typical fluid). Amorphous materials are also called amorphous or glassy materials, which are a large class of rigid solids with high hardness and high viscosity coefficients comparable to crystalline substances (usually 10 poise, that is, 10 Pa·s or more, is 10 times the viscosity coefficient of a typical fluid). However, the spatial arrangement of its constituent atoms and molecules does not exhibit periodic and translational symmetry, and the long-range order of the crystalline state is destroyed; it is only due to the interaction between atoms, which makes it in a cell with several atomic (or molecular) diameters. The domain has short programs. Since there is no effective experimental method to accurately determine the atomic structure of amorphous materials, the above definitions are relative. Amorphous materials have three basic characteristics. ① There are only short programs in the small interval, without any long programs; the wave vector k is no longer a good quantum number to describe the state of motion (see the energy bands of solids). ② Its electron diffraction, neutron diffraction and X-ray diffraction patterns are composed of wider halos and diffuse rings; no diffraction contrast formed by grain boundaries, crystal defects, etc. can be seen with an electron microscope. ③Amorphous solids of any system are metastable compared with their corresponding crystalline materials. When the temperature is continuously heated, in a very narrow temperature region, obvious structural changes will occur, from amorphous to crystalline. This crystallization process mainly depends on the atomic diffusion coefficient, interfacial energy and melting entropy of the material ( see Structure Relaxation)