Compositional Changes at the Early Stages of Nanoparticles Growth in Glasses

Doping material with nanoparticles is increasingly used as an effective method for improving their mechanical, "optical, and sturdiness properties in many fields. More specifically, effective material development will depend on our ability to control nanoparticles' shape, composition, and size. While crystalline nanophase can be examined easily, characterization of amorphous nanoparticles remains a challenge. Here, we investigate the chemical composition of sub-20-nm oxide nanoparticles grown in rare-earth doped silicate glass through the phase separation mechanism occurring under heat treatment. Using a combination of analytical techniques, we demonstrate that nanoparticle composition and, therefore, the chemical environment of encapsulated rare-earth ions, is nanoparticle size dependent. This new experimental evidence of composition change contributes unique insights on the phase separation mechanism that will lead to better comprehension and will guide development of future materials.