New glass-ceramic emits light when under mechanical stress
Researchers created a new glass-ceramic that emits light in response to mechanical stress. The highly transparent material is made from a potassium germanate glass matrix embedded with chromium-doped zinc gallate (ZGO) crystals that give the material its mechanoluminescent properties. Credit: Lothar Wondraczek, Friedrich Schiller University Jena

Researchers have created a glass-ceramic that emits light when stressed. A light source that is switched on by mechanical stress could be created using the new material. It could be useful for monitoring stress in artificial joints in the body or warning of dangerous stress in structures.

Most materials are made as powders, which aren't very versatile. The glass-ceramic material we designed allows glass-like processing approaches to be used to form virtually any shape that can be incorporated into various components and devices.

The United Nations International Year of Glass is celebrated in the special issue of Optical Materials Express.

The glass-ceramic is made from zinc-doped ZGO crystals embedded in a glass matrix. These crystals are so small that they don't have a noticeable effect on the transparency of the glass.

Wondraczek said that their work could help find widespread use in a variety of applications. It ties in with the International Year of Glass by showing the wide variety of glassy materials.

It's a more practical material.

Mechanoluminescent powders are difficult to form into various geometries and require additional processing steps. Glass-ceramics were used to create a more practical material.

There is a new type of material called glass-ceramics. The glass matrix allows these materials to be shaped with many of the same processes used for glass, and the crystals can be used to give them very specific properties.

The researchers created the mechanoluminescent glass-ceramic by developing an extremely fast and stable crystallization process that allows the small ZGO crystals to form in the glass after it has been shaped. The ball-drop test was used to show that the materials emit light under mechanical stress. The correlation between the impact energy and the mechanoluminescence response was discovered by Wondraczek.

They plan to adapt the glass composition so that it can be formed into sheet-like objects, optical fiber and microscale spherical beads, and then explore how these could be used in components and devices. They want to get new functions from the glassy materials by exploiting other features.

More information: Jiangkun Cao et al, Mechanoluminescence from highly transparent ZGO:Cr spinel glass ceramics, Optical Materials Express (2022). DOI: 10.1364/OME.459185 Journal information: Optical Materials Express