Preparation And Performance Characterization Of Er³⁺/Nd³⁺ Co-doped With NaYF₄ Luminescent Materials

The rare-earth luminescent materials have become the focus and frontier of luminescent materials research due to their strong absorption characteristics,stable physical and chemical properties,high luminescence conversion efficiency,and occupy a pivotal position in national economy and defense construction in recent years.This paper focuses on the up-conversion luminescent materials in rare-earth luminescent materials,which absorb long waves and then radiate short waves,and the aim is to clarify the influence of different doping systems and doping concentrations on the structure and properties of materials by combining first-principles calculations with experimental preparations.The structural properties,electronic properties and optical properties of undoped?-NaYF₄ system,Er³⁺doped?-NaYF₄ system and Er³⁺/Nd³⁺doped?-NaYF₄ system are calculated by Materials Studio software.Compared with the undoped system,the introduction of Er³⁺and Er³⁺/Nd³⁺don't destroy the hexagonal phase structure of the crystal,but the volume is slightly expanded,and the forbidden band width is greatly reduced,which is more conducive to electron transition.At the same time,after the doping of Er³⁺and Er³⁺/Nd³⁺,the absorption rate of the system in the infrared band is increased,and the absorption rate of the Er³⁺/Nd³⁺doping system in the infrared band is higher than the Er³⁺doping system,which is more propitious to the implementation of up-conversion luminescence.Different doping concentrations of NaYF₄:Er³⁺/Nd³⁺up-conversion phosphors are prepared by hydrothermal method,and the obtained samples are all pure?-NaYF₄ phase with complete morphology and uniform size.Under the excitation of 808 nm and 980 nm laser,the emission spectrum of each sample has three different positions of luminescence peaks,and the three luminescences are all two-photon processes.Under the excitation of808 nm laser,the pump power can change the emitting color of the sample,and the green purity of the sample is higher with the increase of the pump power.Under the excitation of980 nm laser,the regulation of the pump power can't basically change the green-to-red ratio of the samples,so that the green purity of the samples doesn't change significantly.A comprehensive comparison of the six different concentrations of samples shows that the sample(NaYF₄:2%Er³⁺,0.2%Nd³⁺)has the highest purity of green color under both excitation conditions,which is of great significance in solid-state lighting and display.