Preparation And Optical Properties Of Ag⁺ Doped Bi₂WoO₆:Yb³⁺,Tm³⁺ Inverse Opal Photonic Crystals

With the development of science and technology,researchers have succeeded in manufacturing semiconductor materials based on the characteristics of electrons.In order to control photons like manipulation of electrons,people began to explore the performance of photons.In the research,it is found that there is no interaction between photons and the photon transmission speed is faster than the electron transmission speed.Therefore,photons have become one of the hotspots of research in the 20th century.It has been found that photonic crystals?also known as"optical semiconductors"?can be used to manipulate the propagation path of photons.Photonic crystal refers to an optical material with a periodic structure called a photonic band gap.Photons in the vicinity of the photonic band gap are locally prohibited from propagating in the material.The periodic structure of the artificial opal photonic crystal is the same as that of the natural opal photonic crystal.A certain material is filled in the gap of the artificial opal,and the inverse opal crystal is obtained by removing the opal template by physical and chemical methods.In this paper,two opal photonic crystals,polystyrene?PS?and polymethyl methacrylate?PMMA?,were studied.Both were prepared by emulsion polymerization.The ordered three-dimensional photons were arranged under the action of capillary force and gravity.Crystal.Ag⁺and Yb³⁺,Tm³⁺co-doped Bi₂WO₆ upconversion luminescent materials were prepared by hydrothermal method and sol-gel method.Ag⁺and Yb³⁺,Tm³⁺co-doped Bi₂WO₆ precursor sol prepared by Sol-Gel method were filled into PMMA opal,and calcined at high temperature to obtain Bi₂WO₆ inverse opal photonic crystal.The samples were characterized and analyzed by XRD,UV-3600?spectrophotometer?,SEM and XPS.?1?PS and PMMA opal photonic crystal templates prepared by vertical deposition method have good light transmittance,they are in face-centered cubic structure.?2?Preparation of Ag⁺doped Bi₂WO₆:3%Yb³⁺,1%Tm³⁺by hydrothermal method.The sample was spherical.The co-dope of Ag⁺with Yb³⁺and Tm³⁺did not change the crystal structure of Bi₂WO₆.Upconversion luminescence of Yb³⁺,Tm³⁺doped Bi₂WO₆ with Ag⁺concentrations of 0.1%,0.3%,and 0.5%was measured at the same power using a 980 nm laser.It was found that 0.3%Ag⁺and 3%Yb³⁺,1%Tm³⁺co-doped Bi₂WO₆ have the strongest up-conversion luminescence.?3?The Sol-Gel method was used to prepare 0.5%Ag⁺doped Bi₂WO₆:6%Yb³⁺,1%Tm³⁺.The sample was found to be in the shape of crushed stone.The Ag element was present in the Bi₂WO₆ nanopowder in the form of Ag⁺.Adding 0.5%Ag⁺Bi₂WO₆:Yb³⁺,Tm³⁺the characteristic peak position is consistent with the Bi₂WO₆ standard card.The hydrothermal method for preparing Bi₂WO₆ has a large particle size and it is difficult to fill the opal.Therefore,when the inverse opal is constructed,Bi₂WO₆ prepared by the sol-gel method is used as a precursor.?4?Under the excitation of 980nm infrared laser,the PMMA opal with the band gap position at 1045nm and 1321nm was used as template to prepare0.5%Ag⁺doped Bi₂WO₆:6%Yb³⁺,1%Tm³⁺the inverse opal sample was recorded as IOPC1 and IOPC3 to prepare Bi₂WO₆:6%Yb³⁺,1%Tm³⁺the inverse opal samples were recorded as IOPC2 and IOPC4,and the disordered samples prepared after mixing the two microspheres were recorded as REF.The IOPC1^IOPC4 and REF samples have luminescence peaks at 487nm,525nm,545nm,657nm and 671nm,and the corresponding energy level transitions are¹D₂?³H₆,¹D₂?³F₄,¹G₄?³H₆,¹G₄?³F₄ and ³F₂?³H₆.There is a cross-relaxation energy transfer process during luminescence,namely¹G₄+³H₄?³F₄+¹D₂ and¹G₄+³H₆?³H₅+³H₄.?5?The up-conversion luminescence of IOPC1 and REF indicates that the luminescence is significantly inhibited when the position of the thulium ion luminescence peak overlaps with the inverse optophotonic band gap position;the IOPC2 and REF upconversion luminescence indicate that the thulium ion luminescence peak position is in the photonic band gap.At the edge of the position,the luminescence is significantly enhanced.The luminescence peaks of IOPC1 and IOPC2,IOPC3 and IOPC4 indicate that the luminescent peaks at525nm,545nm,657nm and 671nm are significantly enhanced by the inverse opal doped with silver ions.It indicatdes that silver ions participate in the energy transfer process between rare earth ions.