Structure and optical properties of transparent Er 3+ -doped CaF 2 –silica glass ceramic prepared by controllable sol–gel method

Transparent Er3+-doped CaF2-silica glass ceramics were prepared by the direct physical introduction of Er3+ doped CaF2 nanocrystals into acid-catalyzed sol-gel silica glass. The physical methods of ball milling, ultrasonic baths, and stirring were investigated to disperse Er3+ doped CaF2 nanocrystals in the silica sols. The CaF2-silica sol mixture went through gelation and heat-treatment to form Er3+-doped CaF2-silica glass ceramics. The morphology of Er3+ doped CaF2 in silica glass did not change after heat-treatment at 600 degrees C for 10 h. The experimental results showed that Er3+ doped CaF2 in the glass ceramic prepared with the assistance of ball milling possesses the best dispersity and homogeneity. The highest in-line transmittance of the glass ceramic reached up to 85% in visible region. Glass ceramic exhibits efficient up-conversion emissions corresponding to the Er3+:F-4(9/2)-> I-4(15/2) transition and long lifetime of F-4(9/2) level (1.73 ms) under 980 nm excitation. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.