Crystallization studies on rare-earth co-doped fluorozirconate-based glasses

• Nucleation and growth of BaCl2 in fluorozirconate-based glasses are investigated.
• Eu-doping affects hexagonal to orthorhombic phase transformation.
• Activation energy for phase transformation increases with increasing Eu2 + content.
• Co-doping with trivalent rare-earth ions also affects BaCl2 nucleation and growth.

This work focuses on the structural changes of barium chloride (BaCl2) nanoparticles in fluorochlorozirconate-based glass ceramics when doped with two different luminescent activators, in this case rare-earth (RE) ions, and thermally processed using a differential scanning calorimeter. In the first step, only europium in its divalent and trivalent oxidation states, Eu2+ and Eu3+, is investigated, which shows no significant influence on the crystallization of hexagonal phase BaCl2. However, higher amounts of Eu2+ increase the activation energy of the phase transition to an orthorhombic crystal structure. In the second step, nucleation and nanocrystal growth are influenced by changing the structural environment of the glasses by co-doping with Eu2+ and trivalent Gd3+, Nd3+, Yb3+, or Tb3+, due to the different atomic radii and electro-negativity of the co-dopants.