Controlling the Metastable States of Glasses by External Fields

Glass is a noncrystalline amorphous solid showing glass transition characteristic. It can transform from one metastable state to another metastable or stable state in an external field. In glasses, novel functions can be achieved if we control the status, morphology, and distribution of external field‐induced structures. In this article, we review controlled crystallization of glass by the external fields, that is, control of ligand field, local symmetry, and energy transfer of active ions, etc. by temperature field to achieve efficient broadband near‐infrared emission and optical amplification. We also discussed highly localized crystallization in glass by electron beam and femtosecond laser. Finally, we introduced a novel process for the fabrication of glass ceramic fibers.