The Upconversion Luminescence Properties Of Er³⁺/Ho³⁺,Er³⁺/Yb³⁺/Mn²⁺ Doped Tetrafluoride/Pentafluoride

Anti-Stokes luminescent materials are known as upconversion luminescent materials,which can convert multiple low-energy photons into high-energy photons and are new photoluminescent materials.China's rare earth resources reserves are very rich,and rare earth materials have strong practical value in many fields,such as solar cells in the new energy field,bio-imaging,non-contact temperature measurement,nano-probes in the biomedical field,etc.However,the materials have limitations,such as the lower up-conversion efficiency and difficult to adjust emission color,which largely limit their development and application.In this paper,the same activator ion Er³⁺is chosen to study the upconversion luminescence performance in Na YF₄:Er³⁺/Ho³⁺,Na Er F₄:Ho³⁺,K₂YF₅:Er³⁺/Ho³⁺and K₂Er F₅:Ho³⁺phosphors.When Ho³⁺ion are doped in these phosphors,the tunable emission color of Er³⁺ion is investigated.In addition,the effect of doping heterogeneous metal Mn²⁺ion in K₂YF₅:Yb³⁺,Er³⁺phosphor and K₂Er F₅:Yb³⁺phosphor on the upconversion luminescence performance of Er³⁺ion was also studied.The main studies are as follows:(1)A series of NaErF₄:Ho³⁺and NaYF₄:Er³⁺/Ho³⁺phosphors were prepared by hydrothermal method,and the luminescence properties of the samples were mainly investigated.Under 980 nm laser excitation,the Na Er F₄:Ho³⁺phosphor exhibited red emission(630 nm-700 nm)and the Na YF₄:Er³⁺/Ho³⁺phosphor exhibited green emission(520 nm-560 nm).The doping of Ho³⁺ion increases the upconversion luminescence intensity in Na YF₄:Er³⁺and Na Er F₄phosphors.The maximum in the intensity of the red emission peak of the samples with Ho³⁺ion doped in Na Er F₄samples is 8.55 times than that of the samples without Ho³⁺ion.Ho³⁺ion were doped in Na Er F₄phosphor to achieve tunable emission from yellow-green to red.(2)A series of K₂YF₅:Er³⁺/Ho³⁺and K₂Er F₅:Ho³⁺phosphors were prepared by solvothermal method with polyvinylpyrrolidone(PVP)as surfactant,and the luminescence properties of the samples were investigated.Under 980 nm laser excitation,red emission(630 nm-700 nm)is stronger than green emission(510 nm-580 nm)in K₂Er F₅:Ho³⁺phosphors;green emission(510 nm-580 nm)is stronger than red emission(630 nm-700nm)in K₂YF₅:Er³⁺/Ho³⁺samples.With the doping of Ho³⁺ion,the upconversion emission intensities of K₂YF₅:Er³⁺and K₂Er F₅phosphors are increased.Ho³⁺ion doped in K₂Er F₅sample increased the intensity of the red emission peak of the samples up to 9.47 times than that of the Ho³⁺ion undoped samples.Ho³⁺ion were doped in K₂Er F₅phosphor to achieve tunable emission of the sample from yellow-green to red.(3)A series of K₂Er F₅:Yb³⁺/Mn²⁺,K₂YF₅:Yb³⁺/Er³⁺/Mn²⁺phosphors were prepared by solvothermal method with PVP as surfactant.Mn²⁺ion doped in K₂Er F₅:Yb³⁺and K₂YF₅:Yb³⁺/Er³⁺phosphors improved the upconversion luminescence intensity of the samples.The maximum upconversion luminescence intensity of the sample was 3.04 times higher than that without Mn²⁺ion when the K₂Er F₅:Yb³⁺sample was doped with 20 mol%Mn²⁺ion under 980 nm laser excitation.Mn²⁺ion doping in K₂Er F₅:Yb³⁺phosphor compared with doping in K₂YF₅:Yb³⁺/Er³⁺phosphor resulted in shift in the strong emission peak of the emission spectrum,which achieve tunable emission from green to yellow-green of the sample.The doping of Mn²⁺ion in the same matrix shifts the strong emission peak in the emission spectrum,which has an advantage for adjusting the fluorescence color of the sample.