Comparison of upconversion luminescent properties and temperature sensing behaviors of beta -NaYF sub(4):Yb super(3+)/Er super(3+) nano/microcrystals prepared by various synthetic methods

In this paper, Yb super(3+)/Er super(3+) co-doped hexagonal NaYF sub(4) have been successfully synthesized by solvothermal, thermal decomposition, hydrothermal and molten salt method, respectively. The crystal structures, particle morphologies, sizes and corresponding upconversion luminescent properties of beta -NaYF sub(4):Yb super(3+)/Er super(3+) nano/microcrystals are systemically studied. It is interesting to observed that the temperature-dependent UC luminescent properties of beta -NaYF sub(4):20 %Yb super(3+), 2 %Er super(3+) samples are strongly related to their synthesis methods. Comparison of the upconversion luminescence and thermal sensitivity between the beta -NaYF sub(4):Yb super(3+)/Er super(3+) samples reveals that beta -NaYF sub(4):Yb super(3+)/Er super(3+) sub-microplates synthesized by thermal decomposition method have much stronger green emission intensity, better luminescent thermal stability and higher temperature sensitivity. This findings are relevant to the application of beta -NaYF sub(4):Yb super(3+)/Er super(3+) in optical temperature sensors and to the further understanding of the UC luminescent mechanism.