Synthesis,Luminescent Properties And Application Of Ce³⁺,Cu⁺,Mn²⁺ Doped CaS:Eu²⁺@CaZnOS Phosphors

Eu²⁺activated alkaline earth metal sulfide phosphor CaS:Eu has the spectral conversion performance of absorbing green light and emitting red light,but its poor chemical stability and thermal stability make it difficult for practical applications.According to this,the surface modification is performed by generating a coating layer CaZnOS on the surface of CaS,and finally a core-shell structure phosphor CaS:Eu@CaZnOS with high thermal and chemical stability is obtained.In order to further expand the application of this kind of high-stability phosphors in plant growth,this article is based on CaS:Eu@CaZnOS,doped with different activator ions Ce³⁺,Cu⁺,Mn²⁺to synthesize a series of core-shells with double light conversion properties.Luminous phosphors,and in-depth study of its optical properties.The main research contents are as follows:1.Under the protection of inert gas N₂,CaS:Eu,Ce@CaZnOS:x%Ce phosphors were synthesized by high-temperature solid-phase method.Compared with CaS:Eu@CaZnOS,the blue-green to red luminescence intensity of CaS:Eu,Ce@CaZnOS:x%Ce phosphors is significantly increased,and when x=0.7%,the red light emission intensity reaches the maximum.It is found through research that CaZnOS:Ce obtains an emission spectrum with a peak of 555 nm under the excitation of 475 nm blue-green light.This emission band overlaps with the broad excitation band of CaS:Eu phosphor from 450 nm to 600 nm.In CaS:Eu,Ce@CaZnOS:Ce,there is energy transfer from Ce³⁺on the shell to Eu²⁺in the core.The hand-held spectrometer test of the laminated glass made by mixing it with liquid glue shows that the red light ratio of the laminated glass is higher than that of the blank glass,and is closer to the optimal red light ratio required for plant growth.Therefore,the highly stable CaS:Eu,Ce@CaZnOS:Ce phosphor with greatly improved luminous intensity from green to red has better practical application value.2.Based on the need for a certain amount of blue and red light for plant growth,the CaS:Eu@CaZnOS:x%Cu phosphor that converts purple to blue in the shell and green to red in the core is realized by Cu⁺doping.The test shows that CaS:Eu@CaZnOS:x%Cu phosphor has two luminescence centers:the blue emission band in the range of 460+10 nm can be obtained under the excitation of near ultraviolet light of about 333nm,which belongs to the shell CaZnOS:Cu.Under the excitation of green light at 520 nm,a red light emission spectrum with a peak of about 650nm can be obtained,which is derived from the 5d-4f transition of Eu²⁺in Core CaS:Eu.In addition,the imaging method of an inverted fluorescence microscope further proved that the CaS:Eu@CaZnOS:Cu phosphor has the dual excitation and dual emission characteristics of ultraviolet excitation to emit blue light and green light to emit red light.Therefore,this core-shell luminescent CaS:Eu@CaZnOS:Cu phosphor can be used as a potential solar spectrum conversion agent for plant growth.3.The CaS:Eu@CaZnOS:Mn,Cu phosphor with purple to blue/red in the shell and green to red in the core is realized by Mn²⁺/Cu⁺doping.The spectrum of CaS:Eu@CaZnOS:Mn phosphor shows that,in addition to the red emission band of CaS:Eu with a peak at 650 nm,an orange-red emission band with a peak at about 615 nm appears under the excitation of 295 nm ultraviolet light.This emission band is attributed to Mn²⁺in CaZnOS.The CaS:Eu@CaZnOS:Mn,Cu phosphor combines the green-to-red luminescence of Eu²⁺,the purple-to-blue luminescence of Cu⁺,and the purple-to-orange-red luminescence of Mn²⁺.Therefore,these two types of phosphors both have the excellent green-to-red spectral conversion performance of CaS:Eu,and their shells can convert ultraviolet light to reduce the damage of ultraviolet light to plants and improve the quality of blue and red light.