Structural environment influence on Faraday effect in Tb3+and Pr3+co-doped fluorophosphate glass and glass-ceramics containing TbOF nanocrystals

The influence of structural environment of lanthanide ions on the co-doping Faraday effect is explored within fluorophosphate glasses and glass ceramics. In a first part, the crystallization process of a glass with a nominal composition 35 NaPO3 - 15 BaF2 - 50 TbF3 is explored in function of duration and temperature of the ceramization process. X-ray diffraction analysis and STEM-HAADF allowed the identification of crys-talline TbOF cubic fluorite phase in these glass-ceramics, with a maximum crystalline fraction of 42 +/- 2 wt% for a crystallite size of 46 nm for the sample heat-treated 10 h at 394 degrees C. In a second part, TbOF glass-ceramics following the composition law 35 NaPO3 - 15 BaF2 - 0.5 ((10 0-x) TbF3 - x PrF3) with x = 0, 1, 2, 3, 4 and 5 are prepared at the optimal heat treatment of 10 h at 394 degrees C corresponding to maximal crystalline fraction and optical transmission. The Verdet constants of these co-doped glass-ceramics are characterized and compared to the ones of the parent glasses. The maximum co-doping efficiency reaches 1.075 for the glass-ceramic, compared to a value of 1.037 for the corresponding co-doped glass samples. The structural organization around the lanthanide cation site increases the co-doping influence on the Faraday Effect by optimization of the superexchange interaction. (c) 2023 Elsevier B.V. All rights reserved.