Study Of Interaction Between Rare Earth Ions And CdSe?PbF₂ Nanocrystal In Silicate Glass

Nano-structured materials can be the first choice for the materials between the bulk materials and molecular materials.Their physical properties,which are different from those of bulk materials,provide possibilities for new applications,especially in the fields of electronics,optoelectronics and biochemistry.The growth of quantum dots in glass matrix is restricted by many factors and requires the nucleating agent.Rare earth ions and transition metals are often used as dopants.As common fluorescent materials,rare earth ions have complex energy level structure,stable luminescence and high conversion rate.Rare earth ions have excellent luminescence in infrared regions,which other materials don't.However,the luminescence properties of rare earth ions are very sensitive to the complexation state and crystal field state of the matrix materials.The microenvironment with high phonon energy limits the luminescence of rare earth ions in the mid-infrared region.The low phonon energy environment of semiconductor nanocrystals may improve the infrared luminescence of rare earth ions.Therefore,semiconductor nanocrystals and rare earth ion composite materials can combine the advantages of the two materials and make up for the shortcomings of the two materials.It can also achieve a wider range of luminous area.In order to study the interaction between rare earth ions and semiconductor nanocrystals,the specific work is as follows:1.The glass components of 50SiO₂-20Na₂O-5Al₂O₃-21ZnO-4ZnSe were used to prepare samples without doping with 0.5 mol%Nd³⁺,1 mol%Nd³⁺,0.5 mol%Er³⁺and 1mol%Er³⁺of different heat treatment systems.We tested the luminous properties and structural changes of the materials.We found that the growth of ZnSe was not affected by the rare earth ions,and the fluorescence lifetime of the rare earth ions only changed slightly.This may be due to the small Zn²⁺radius,the rare earth ions failed to enter the ZnSe lattice.Therefore,the interaction between Nd³⁺and Er³⁺and ZnSe is not obvious.For this purpose,CdSe quantum dots were prepared by using Cd²⁺with a large ion radius.We used the glass components of 99%?50SiO₂-25Na₂O-10BaCO₃-5Al₂O₃-10ZnO?-1%?50ZnSe-50CdO?to prepare samples doped with 0.5 mol%Nd³⁺,1 mol%Nd³⁺,0.5mol%Er³⁺and 1 mol%Er³⁺and undoped samples.We tested the luminous properties and structural changes of the materials.It is found that both Er³⁺and Nd³⁺ions acted as nucleating agents and promoted the nucleation of CdSe quantum dots.However,due to the limitation of quantum dots'raw materials,rare earth ions limited the growth of quantum dots.With the growth of CdSe quantum dots and the environment of rare earth ions,the life of rare earth ions decreased with the increasing of heat treatment temperature.2.The glass components of 55SiO₂-10Al₂O₃-35PbF₂ were used to prepare undoped samples,Ho³⁺and Er³⁺samples of various concentrations.We tested the optical properties of the materials.The energy transfer processes from Er³⁺:⁴I_11/2 to Ho³⁺:⁵I₆ and Er³⁺:⁴I_13/2 to Ho³⁺:⁵I₇ are discussed.At the same time,the nucleation and growth of PbF₂ nanocrystals in the matrix became more complete with the increase of heat treatment temperature.Both Ho³⁺and Er³⁺enrichment in PbF₂ nanocrystals were observed by transmission electron microscope.Changes in the microenvironment and the reduction in the distance between rare earth ions resulted in obvious energy transfer.We can clearly observe that with the nucleation and growth of PbF₂ nanocrystals,the²000 nm infrared luminescence of Ho³⁺ion is effectively enhanced.