Controlled Hydrothermal Synthesis and Photoluminescence of Nanocrystalline ZnGa2O4:Cr3+Monospheres.
The hydrothermal synthesis of nanocrystalline ZnGa2O4:Cr3+(ZGC) red phosphor monospheres was accomplished in this work, and the effects of system pH, reactant content, reaction time, and citrate anions (Cit3-) on the phase and morphology evolution of the product were systematically studied. Under the optimized conditions of Cit3-/M = 1.0 molar ratio (M = total cations), pH = 5.0, and 0.2 mmol of Zn2+, well-dispersed ZGC monospheres with an average diameter of ~454 ± 56 nm (average crystallite size ~15 nm) were successfully obtained via hydrothermal reaction at 180 °C for 18 h. Cit3+ions were demonstrated to be crucial to the formation of monospheres and substantially affect the pathway of phase formation. The ZGC monospheres calcined at 800 °C (average diameter ~353 ± 59 nm; average crystallite size ~30 nm) have an intensity ~6 times that of the original phosphor for the 700 nm red emission of Cr3+(the2E →4A2transition) under excitation with the O2-→ Ga3+charge transfer band at 250 nm. Fluorescence decay analysis found that the 700 nm emission has lifetime values of ~5 ms for the ZGC phosphors.
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning, 110819, China.|Institute of Ceramics and Powder Metallurgy, School of Materials Science and Engineering, Northeastern University, Shenyang, Liaoning, 110819, China.
Tian
T
Luan
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning, 110819, China.|Institute of Ceramics and Powder Metallurgy, School of Materials Science and Engineering, Northeastern University, Shenyang, Liaoning, 110819, China.
Jinhan
J
Liu
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning, 110819, China.|Institute of Ceramics and Powder Metallurgy, School of Materials Science and Engineering, Northeastern University, Shenyang, Liaoning, 110819, China.
Xiaoxue
X
Yuan
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning, 110819, China. LI.Jiguang@nims.go.jp.|Institute of Ceramics and Powder Metallurgy, School of Materials Science and Engineering, Northeastern University, Shenyang, Liaoning, 110819, China. LI.Jiguang@nims.go.jp.|Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan. LI.Jiguang@nims.go.jp.
Ji-Guang
http://orcid.org/0000-0002-5625-7361
JG
Li
Cr red phosphor; Hydrothermal synthesis; Monospheres; Photoluminescence; ZnGa2O4