Crystalline materials are explained in Mechanical Base that they have much more packed and regular structures when they are solidifed. But when the crystalline materials are melted, this packed structure is lost. In this phase, there are no regular arrangements between atoms or molecules. In this article, we will explain the materials have this irregular arrangement of atoms even in solid phase, called amorphous(non-crystalline) materials.
The main difference between the amorphous materials and crystalline materials is the regular and packed arrangement in solid state. In amorphous materials, there is no regular and packed arrangement between atoms and molecules.
Also there is a great difference between in the phase transition characteristics between the amorphous materials and the crystalline materials.
In crystalline materials, phase change between the solid and liquid state is abrupt. There is a specific temperature for this phase transition for crystalline materials. Molecules or atoms tranfer abruptly from regular-packed solid arrangement to irregular unpacked liquid arrangement or vice versa at melting temperature.
But in non-crystalline materials, there is no abrupt change in physical state of material such as fully liquid or fully solid. There is a very slow transition between these fully solid or fully liquid states of amorphous material. For example, glass is a very good example for amorphous materials, transition of glass from solid state to the liquid state is not a abrupt process. Glass liquifies slowly, in the starting of liquification, the viscosity is very high. This transition state of glass or amorphous materials is called as ‘supercooled state’. After a certain time of heat tranfer to the glass, there will a phase change to the fully liquid state. The temperature that this change occurs called ‘glass transition temperature’ for amorphous materials.
The generaly characteristic differences between the non-crystalline materials and the crystalline materials are like above.
Certain plastics and glass are very good examples of amorphous materials.
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