Introduce the amorphous material

Amorphous materials are also called amorphous or glassy materials, which are a large class of rigid solids with high hardness and high viscosity comparable to crystalline substances (generally at 10 poise, that is, above 10 Pa·s, 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 comparable to crystalline substances (generally at 10 poise, that is, above 10 Pa·s, is 10 times the viscosity coefficient of a typical fluid). However, the spatial arrangement of its constituent atoms and molecules does not show periodicity and translational symmetry, and the long-range order of the crystal state is destroyed; it is only due to the interconnection between atoms that it is in a small area of ​​several atomic (or molecular) diameters. There are short programs in the domain. 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 small intervals, without any long programs; the wave vector k is no longer a good quantum number to describe the state of motion (see 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.

③ The amorphous solid of any system is metastable compared with its corresponding crystalline material. When the temperature is continuously raised, in a very narrow temperature zone, there will be obvious structural changes, from amorphous to crystalline. This crystallization process mainly depends on the atomic diffusion coefficient, interface energy and melting entropy of the material ( see Structural Relaxation)