Extremely intense pure green upconversion luminescence in Ho3+/Yb3+ co-doped BiTa7O19 phosphors under 980 nm laser excitation. - Fan, Yuhan; Cao, Yongze; Liu, Tianshuo; Li, Meiling; Xu, Sai; Zhang, Jinsu; Chen, Baojiu (Applied Physics A: Materials Science & Processing, 2024)