Versatile material that shines under mechanical stress

Scientists have created a new glass-ceramic material that emits light in response to mechanical stress, a property known as mechanoluminescence.

With further development, the new material could be used to create a new kind of light source, which is turned on by mechanical stress.

The material could be useful for monitoring the load on artificial body joints or warning of dangerous stresses or fractures in buildings, bridges and other structures.

Most materials that exhibit mechanoluminescence have been made in powder form, which is not very versatile, argues Lothar Wondraczek of the Friedrich Schiller University of Jena in Germany and a member of the research and development team. In addition to being difficult to mold into the necessary geometries, mechanoluminescent powder requires additional processing steps, such as encapsulation in a matrix material.

In contrast, the new mechanoluminescent glass-ceramic material allows the use of processing techniques very similar to those used for glass. And the new material can be given virtually any shape, including fibers, beads or microspheres that can be incorporated into various components and devices.

The new glass-ceramic material emits light in response to the mechanical stress it undergoes. (Photo: Lothar Wondraczek, Friedrich Schiller University Jena)

The new glass-ceramic material, which has a high degree of transparency, is made of chromium-doped zinc gallate crystals in a matrix of potassium germanate glass.

These crystals give the material its mechanoluminescent properties, but they are so small that they reduce the visual transparency of the glass very little.

In the tests carried out, Wondraczek and his colleagues have verified that the mechanoluminescent response of the new glass-ceramic material is reproducible and rechargeable. They have also found that the material exhibits a direct correlation with the impact energy. In other words, the greater the mechanical stress it experiences, the more intense the light it generates.

Wondraczek’s team exposes the technical details of the new material and the process used to manufacture it in the academic journal Optical Materials Express, under the title “Mechanoluminescence from highly transparent ZGO:Cr spinel glass ceramics”. (Font: NCYT by Amazings)