@article{SisLab3809,
          volume = {35},
          number = {4},
           title = {Influences of growth durations on characteristics of NaYF4:(Yb,Tm) upconversion materials},
          author = {Thi Dung Nguyen and Van Thanh Hoang and Dinh Lam Nguyen},
       publisher = {VNU Journal of Science: Natural Science and Technology},
            year = {2019},
         journal = {Influences of growth durations on characteristics of NaYF4:(Yb,Tm) upconversion materials},
             url = {https://eprints.uet.vnu.edu.vn/eprints/id/eprint/3809/},
        abstract = {NaYF4:(Yb,Tm) upconversion materials  were synthesized by the simple hydrothermal method. Growth duration was varied from 4h to 12h under a growth temperature of 150oC. The structural, optical and surface morphology characteristics of the NaYF4:(Yb,Tm) UC materials were investigated. The XRD and SEM results illustrated that the NaYF4:(Yb,Tm) materials were transformed from the multiple phases (hexagonal and cubic) to the single-phase (hexagonal prism) as growth duration being longer than 8h with the average diameter and length of these prisms being about 0.5 ?m and 2 ?m, respectively. Under 980 nm laser excitation, the NaYF4:(Yb,Tm) emits at peaks of 450 nm (1D2{$\rightarrow$} 3F4), 475 nm (1G4{$\rightarrow$}3H6), 647 nm (1G4{$\rightarrow$}3F4) and 697  nm (3F3{$\rightarrow$}3H6), with the highest emission belonging to NaYF4:(Yb,Tm) grown for 8h.}
}