Feststoffliche

Feststoffliche is an adjective used in German to describe things that pertain to solid matter or the solid phase. It is derived from Feststoff, meaning a solid substance, and is commonly found in scientific contexts such as physics, chemistry, and materials science.

In scientific writing, feststoffliche Eigenschaften, feststoffliche Phasen oder feststoffliche Reaktionen refer to properties, phases or processes that occur in solids, as opposed to liquids or gases. The term is frequently employed to distinguish solid-state phenomena from those in other phases. Within materials science and solid-state physics, feststofflich often appears in discussions of crystallinity, microstructure, defect chemistry, mechanical behavior, and electronic structure.

Typical examples include feststoffliche Eigenschaften like hardness, Young’s modulus, thermal conductivity, and electronic band structure, as well as phenomena such as feststoffliche Diffusion, Festkörperdiffusion, and phase transitions between solid phases. Defects in solids (Gitterdefekte), grain boundaries, and crystallographic anisotropy are also considered in feststofflichen Kontexten, because they strongly influence how solids behave.

The term coexists with related concepts such as Festkörperphysik (solid-state physics), Festkörperchemie (solid-state chemistry) and solid-state engineering, distinguishing solid-phase science from liquid- and gas-phase disciplines. While "feststofflich" and "feststoffliche" are standard in technical German, the everyday language often prefers more general descriptors, depending on the audience and field. Overall, feststoffliche describes the solid-phase nature of materials and their characteristic properties and processes.