Phosphate glasses own many merits, such as low softening and melting temperature, high transparency for visible light, high luminous ion doped concentration, and large emission and absorption cross sections. Unfortunately, pure phosphate glasses possess relatively poor thermal stability, which often limits their practical applications [12]. To solve this problem, the glass composition is supposed to be optimized for achieving stable glass network structure by adding other oxides such as ZnO, SrO and so on. Takebe et al. reported that ZnO is widely used to improve the chemical stability of phosphate glasses [13], performing as an intermediate oxide since Zn2 + owns large ion radius and electronic configuration with 18 outer-shell electrons [14]. Zn2 + can form either [ZnO4] tetrahedron or P–O–Zn bridges via phosphate chains linkages in the glass network structure [15] and [16] and improve the thermal stability of phosphate glasses. Likewise, the addition of SrO in pure phosphate glass can significantly improve the thermal properties due to the formation of meta-phosphate structure [17].