title: Synthesis and upconversion luminescence of YF3:Yb3+ Tm3+ and TiO2-coated YF3:Yb3+, Tm3+ microcrystals.
abstract: YF3:Yb3+, Tm3+ microcrystals were prepared by a microemulsion method. The microcrystals were coated with TiO2 by hydrolysis of titanium n-butoxide (TBOT). Transform electron microscopy and X-ray diffraction were used to characterize the core/shell materials. The results indicated that the low TBOT/YF3 molar ratio was favorable to preparing the uniform TiO2 coatings. The upconversion luminescence properties of YF3:Yb3+, Tm3+ and TiO2-coated YF3:Yb3+, Tm3+ microcrystals were studied under 980-nm excitation. The 1I6 --> 3H6, 1I6 --> 3F4, 1D2 --> 3H6, 1D2 --> 3F4, 1G4 --> 3H6, and 1G4 --> 3F4 emissions were observed. The upconversion mechanisms were discussed in detail.
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, PR China.
authors.forename: Daisheng
authors.initials: D
authors.lastname: Zhang
authors.forename: Weiping
authors.initials: W
authors.lastname: Qin
authors.forename: Guofeng
authors.initials: G
authors.lastname: Wang
authors.forename: Guodong
authors.initials: G
authors.lastname: Wei
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Peifen
authors.initials: P
authors.lastname: Zhu
authors.forename: Ryongjin
authors.initials: R
authors.lastname: Kim
authors.forename: Fuheng
authors.initials: F
authors.lastname: Ding
authors.forename: Kezhi
authors.initials: K
authors.lastname: Zheng
authors.forename: Ning
authors.initials: N
authors.lastname: Liu