Preparation And Properties Of Rare Earth Doped Several Phosphate Up-conversion Luminescent Materials

In this paper,rare earth ions co-doped Y?PO₃?₃,La P₃O₉and YPO₄up-conversion luminescent materials were synthesized by a polyacrylamide gel method and co-precipitation method.The phase structure,thermal properties and up-conversion luminescence properties of the obtained samples were investigated by X-ray diffraction?XRD?and Fourier transform infrared spectroscopy?FT-IR?,Thermogravimetric and differential scanning calorimetry?TG-DSC?,Scanning Electron Microscope?SEM?,Upconversion Fluorescence Spectroscopy?UPL?.Through a lot of research work,some innovative results have been achieved.The polyacrylamide gel method was used to prepare Er³⁺,Yb³⁺co-doped Y?PO₃?₃up-conversion luminescent materials.The p H of reaction system,annealed temperature,annealed time and the ratio of phosphorus to rare earth in the raw materials?n?Ln?/n?P???Ln=Y,Er,Yb?on the phase structure and luminescence properties of the products were studied.It was found that the annealed temperature and the ratio of phosphorus to rare earth in the raw materials?n?Ln?:n?P??directly affect the phase structures of the products.The synthesis process conditions also affect the up-conversion luminescence performances of the samples.The pure phase monoclinic structure Er³⁺and Yb³⁺co-doped Y?PO₃?₃samples with excellent up-conversion emission properties can be obtained under the annealed temperature of the reaction system is 900°C,the annealed time is 15 h,the p H is 1,and?n?Ln?/n?P??is 1:3.The XRD results show that the doping rare earth ions does not significantly change the structure of Y?PO₃?₃.The single phase Y?PO₃?₃and Er³⁺doped Y?PO₃?₃samples do not display any up-conversion emission peaks.Under the excitation of near-infrared light at 980 nm,the Er³⁺and Yb³⁺co-doped Y?PO₃?₃samples emit strong up-conversion emission peaks due to Er³⁺characteristics transitions with Yb³⁺as sensitizer.The emission spectra of Er³⁺and Yb³⁺co-doped Y?PO₃?₃crystals are composed by emission bands of²H_11/2?⁴I_15/2?525 nm?,⁴S_3/2?⁴I_15/2?549 nm?and⁴F_9/2?⁴I_15/2?656 nm?.And the ⁴S_3/2?⁴I_15/2transition is the strongest emission band in emission spectra.The Er³⁺and Yb³⁺co-doped Y?PO₃?₃samples emit up-conversion green light.The three emission bands at 525 nm,549 nm,and 656 nm attribute to the two-photon absorption mechanism.The doping amount of Er³⁺and Yb³⁺directly affect the up-conversion luminescence properties of the Er³⁺and Yb³⁺co-doped Y?PO₃?₃samples.When the doping content of Er³⁺and Yb³⁺is higher than 1%and15%,respectively,a concentration quenching phenomenon will be found in the Er³⁺and Yb³⁺co-doped Y?PO₃?₃samples.A series of Tb³⁺/Yb³⁺,Tm³⁺/Yb³⁺ co-doped,Er³⁺/Tm³⁺/Yb³⁺ triple-doped Y?PO₃?₃ up-conversion luminescent materials were synthesized by a polyacrylamide gel method.The structure and luminescent properties of the samples were studied.The emission spectra of Y?PO₃?₃:Tm³⁺,Yb³⁺samples are mainly composed of some 475 nm?¹G₄?³H₆?,651 nm?¹G₄?³F₄?,696 nm?705 nm(³F_2,3?³H₆),and 801 nm?³H₄?³H₆?.The emission peak at 475 nm is significantly stronger than other emission peaks.The stable and strong Tm³⁺ions characteristic blue light-emitting is obtained in the samples excited by 980 nm near-infrared light.The emission bands at 475 nm and696 nm belonge to the two-photon absorption mechanism.When the Tm³⁺doping concentration is 1%,and the Yb³⁺doping amount reaches 50%,the concentration quenching phenomenon occurs.The Er³⁺/Tm³⁺/Yb³⁺triple-doped Y?PO₃?₃samples excited by 980 nm light show some emission bands of Er³⁺and Tm³⁺ions.The intensities of those emission bands are changed with the increase of the Tm³⁺doping amount.The Y?PO₃?₃:1%Er³⁺,40%Yb³⁺sample exhibits the emission bands of Er³⁺ions,the chromaticity coordinates located on the green region.The chromaticity coordinates of the Er³⁺/Tm³⁺/Yb³⁺triple-doped Y?PO₃?₃samples shift from green to blue region with an increasing Tm³⁺doping content,dueing to the increase of the intensity of Tm³⁺emission peaks and the decline of the intensity of Er³⁺emission peaks,meaning that the up-conversion emission color of the Er³⁺/Tm³⁺/Yb³⁺triple-doped Y?PO₃?₃samples can be tailored by the Tm³⁺doping concentration.The results show that the emission bands of the Tb³⁺,Yb³⁺co-doped Y?PO₃?₃samples excited by 980 nm are constituted by blue,green and orange emission peaks of Tb³⁺ions.The Tb³⁺doping amount directly affects the up-conversion luminescence performance of the prepared product.When the Tb³⁺doping amount is 2%to 10%,the ⁵D₄?⁷F₆emission peak of Tb³⁺splits into two emission peaks at 481 nm and 491nm.The green emission peak at 547 nm is the strongest emission peak with the Tb³⁺doping amount from 5%to 20%.When the Tb³⁺doping amount is higher than 20%,a concentration quenching phenomenon is observed.The ⁵D₃?⁷F₆emission peak of the samples due to the two-photon absorption mechanism.By changing the ratio of Tb³⁺/Yb³⁺,the blue-green color of the sample can be controlled.A polyacrylamide gel method was used to prepare Er³⁺,Yb³⁺co-doped La P₃O₉up-conversion luminescent materials.The p H,annealed temperature,annealed time,and the ratio of phosphorus to rare earth materials in the raw materials?n?RE?:n?P???RE=La,Er,Yb?on the phase structure and luminscent properties of the products were discussed.The results indicate that the annealed temperature and the n?RE?/n?P?directly affect the phase structure of the products.And the synthesis conditions also affect the up-conversion luminescence performances of the samples.The results show that the suitable conditions for the synthesis of Er³⁺,Yb³⁺co-doped La P₃O₉up-conversion luminescent materials have a annealed temperature of 900°C,a pre-annealed time of 7 h,a p H of 9,and?n?RE?/n?P??of 1:5.Under these conditions,a Er³⁺,Yb³⁺co-doped La P₃O₉and YP₃O₉mixed phase crystals can be prepared.Under the excitation of near-infrared light at 980 nm,the samples emit the characteristic²H_11/2?⁴I_15/2?524 nm?,⁴S_3/2?⁴I_15/2?550 nm?,and ⁴F_9/2?⁴I_15/2?660 nm?emission peaks of Er³⁺ions.The peak at 660 nm is significantly higher than other bands,and this band is a two-photon absorption mechansim.Er³⁺/Yb³⁺co-doped YPO₄up-conversion luminescent materials were synthesized by a co-precipitation method.The effects of p H,annealed temperature,and Er³⁺/Yb³⁺doping amount on the phase structure and luminescence properties of the products were analyzed.The luminescent color purity,color temperature and luminescent mechanism of the samples were studied.The results show that the pure phase tetragonal Er³⁺/Yb³⁺co-doped YPO₄samples can be prepared,in which the calcination temperature is an important factor affecting the strucure,size,and up-conversion performance of the samples.The Er³⁺/Yb³⁺co-doped YPO₄crystals with excellent performance can be obtained by calcining at 900°C.Under the excitation of 980 nm,the samples can emit Er³⁺characteristic strong green light emission.The intensities of the emission peaks change with the co-doping content of Yb³⁺and Er³⁺.The sample with the Yb³⁺and Er³⁺co-doping content are 20%and 1%show the best up-conversion luminescence performance.The concentration quenching phenomena will occur for Er³⁺,Yb³⁺co-doped YPO₄samples when the doping contents of Yb³⁺above 20%or the doping contents of Er³⁺above 1%.The color purity of the green up-conversion emission from Er³⁺,Yb³⁺co-doped YPO₄samples above 96%.The color temperature of the Er³⁺,Yb³⁺co-doped YPO₄samples are similar to daylight?5500–6000 K?,which has potential application in the field of lighting and display.The green emission peak at 525 nm for the samples originate from a two-photon absorption process.