Which property of materials does the term "non-crystalline" imply?

The term "non-crystalline" refers to materials that do not have a well-defined, ordered atomic structure typical of crystalline materials. In non-crystalline materials, the atoms are arranged randomly rather than in a regular, repeating pattern. This random atomic arrangement leads to different physical and mechanical properties compared to crystalline materials, such as isotropy in behavior, where the properties are the same in all directions.

Crystalline materials, in contrast, have a fixed geometric arrangement, which contributes to their characteristics, such as defined melting points and certain mechanical strengths. The lack of order in non-crystalline materials affects their thermal and electrical properties, but the focus of the term is specifically on the randomness of their atomic arrangement.