Locally crystallized glass

摘要

Glasses containing one or more rare-earth elements and one or more halides are disclosed including a region locally transformed into crystallized glass that comprises precipitated rare-earth element-containing halide crystals. Also disclosed are molded objects containing dispersed particles of glass containing one or more rare-earth elements and one or more halides and having a region within which the particles are transformed into crystallized glass particles. The crystallized region is invisible under usual light but can be detected using upconversion luminescence generated by irradiation with excitation laser light having a specific wavelength. Disclosed further are methods for preparing such locally crystallized glasses and molded objects comprising irradiating with laser light the substrate, as well as methods for efficient detection of the crystallized region in such glasses or molded objects comprising irradiating the glass substrate or the molded object with laser light to generate upconversion luminescence in the rare-earth element-containing halide crystals.