Hydrothermal Synthesis And Up-conversion Photoluminescence Of Rare-earth Doped Perovskite Nanostructures

Generally,perovskite-structured ferroelectric oxides?ABO₃?are doped with other ions,due to their simple structure,easy doping and large tolerance factor.Therefore,we can adjust their physical and chemical properties by doping,in order to obtain multifunctional perovskite-structured oxides.Among them,rare-earth ions doped into perovskite-structured oxides can effectively achieve the luminescent properties.However,the successful preparation of rare-earth doped perovskite nanomaterials with single crystal structure and uniform size is rarely reported.In this paper,a series of single crystal perovskite nanomaterials doped with different rare earth ions with uniform size have been synthesized via hydrothermal method which is low cost and simple.The main results are as follows:?1?Er³⁺-doped and Er³⁺/Yb³⁺co-doped SrTiO₃ nanocubes are synthesized via a facile hydrothermal method.The UC emissions reveal that green and red emissions centered at 525,550 and 660 nm are observed under 980 nm excited,which can be ascribed to the ⁴H_11/2?⁴I_15/2,⁴S_3/2?⁴I_15/2 and ⁴F_9/2?⁴I_15/2 transitions,respectively.For Er³⁺-doped SrTiO₃ system,the intensity of these up-converted emissions is increased as the doping concentration of Er³⁺increases to 3 mol%.However,when the doping concentration reaches to 5 mol%,the up-converted emissions reduced sharply.For Er³⁺/Yb³⁺codoped SrTiO₃ system,the intensity of both green and red emissions increase as Yb³⁺concentration increases,but the red emission increases faster than that of green one.As a result,the introduced Yb³⁺ions can effectively enhance the emission intensity of Er³⁺-doped SrTiO₃ for the energy transfer process.?2?The Er-doped PTO nanocrystals are synthesized by hydrothermal method,the Er³⁺ions concentrations are 0 to 5 mol%.The results show that the prepared Er-doped PTO nanocrystals were perovskite structures,and Er³⁺ions were doped into the PTO lattice without changing the crystal structure.Excited by 980 nm laser,the up-conversion results indicate that the Er³⁺-doped PTO nanocrystals have strong green emission at 525nm and 550 nm,and red emission concentrated at 660 nm.In addition,the dependence of temperature on the upconversion luminescence of Er³⁺doped PTO nanocrystals is investigated.The sensitivity and trend of the sample in the range of 298-493 K are calculated based on the fluorescence intensity ratio?FIR?,indicating that the material has a relatively large optical temperature sensing sensitivity.?3?In order to investigate the effect of ferroelectric polarization on the UC PL of Er³⁺-doped PTO,the PTO-Er-1 ceramic has been prepared and the in-situ electric field luminescence was tested.It has been found that the fluorescence intensity of the Er³⁺-doped PTO ceramic increased almost 60-80%with the increase of electric field.It implied that the ferroelectric polarization of PTO could control the UC PL.Because of the intensity of polarization would change as the electric field increased.And then the crystalline field would change which may result to the UC PL property.?4?The Ho/Yb co-doped PTO nanocrystals are prepared,with Ho ions concentration of 0-5 mol%and Yb³⁺ions concentration of 8 mol%.The results showed that the prepared PTO nanocrystals are perovskite structures,and Ho and Yb ions are doped into the PTO lattice without changing the crystal structure.The up-conversion results indicate that the Ho/Yb co-doped PTO nanocrystals have strong green emission around at 550 nm and red emissions concentrated at 660 nm and 755 nm.Moreover,the temperature dependence of Ho³⁺/Yb³⁺codoped PTO nanocrystals on the upconversion luminescence was investigated.The sensitivity and trend of the sample in the range of 298-493 K were calculated based on the fluorescence intensity ratio?FIR?,indicating that the material has a relatively large optical temperature sensing potential.