Crystal is an ordered and periodic three-dimensional structure. Its atoms, molecules or ions are arranged in a certain way to form a crystal network with regular repeating units. The crystal has a clear plane and plane angle, and is in a regular geometric shape. Its structure and morphology can be studied and described by crystallography. The arrangement of crystals has definite lattice point and lattice plane, and the properties of crystals are limited by this structure.
Crystal refers to a solid substance without long-range ordered structure. Its atoms, molecules or ions have no fixed arrangement, and there is no clear lattice point and lattice plane. The amorphous structure is irregular, so its shape and structure are irregular and cannot be described by crystallography. Amorphous substances are also called amorphous substances. Common amorphous substances include glass, some plastics and colloidal substances.
There are also differences in physical properties between crystal and amorphous. Crystals have a definite melting point and freezing point, while amorphous crystals usually have a continuous glass transition temperature range. The crystal shows regular periodicity at the sub-crystal point, which leads to obvious crystal diffraction pattern under X-ray or electron beam irradiation, while amorphous crystal has no clear diffraction pattern under irradiation.
Origin of Crystallization and Amorphousness
The formation of crystals is due to the fact that when a substance is in a solid state, its atoms, molecules or ions form a crystal network with regular repeating units in a periodic way according to a specific arrangement, a certain lattice point and a certain crystal plane. The process of crystal formation usually includes slow cooling, precipitation and crystallization of substances from molten state or solution, as well as other solid phase transition processes. In this process, atoms or molecules are arranged and rearranged in order to form crystals with regular shapes and structures.
Amorphous crystals are formed because when a substance is in a solid state, its atoms, molecules or ions have no definite ordered arrangement and lattice point. In amorphous, the distribution of atoms or molecules is relatively disordered, showing an irregular and disordered form. Amorphous crystals can be formed by rapid cooling or solidification, so that there is not enough time for substances to form ordered structures. In addition, the solid form of some substances can also be amorphous, and they will not form a clear crystal structure even under the condition of slow cooling or solidification.