Behavior of Yb<sup>3+</sup> and Er<sup>3+</sup> during Heat Treatment in Oxyfluoride Glass Ceramics

<table>Energy-level diagram of Yb<sup>3+</sup> and Er<sup>3+</sup> ions and possible upconversion mechanisms.</table>

Journal of Nanomaterials

Figure 10: Behavior of Yb<sup>3+</sup> and Er<sup>3+</sup> during Heat Treatment in Oxyfluoride Glass Ceramics 