Design Optimization Of Preparation Process For Gadolinate Luminescent Materials

Due to the excellent ultraviolet light absorption efficiency of gadolinium ions and the high degree of compatibility with rare earth ions in the luminescent center,the possibility of transferring energy to the activated ions is greatly enhanced,so gadolinate is a kind of excellent photoluminescent material.In this paper,Ca Gd₄O₇?CGO?and Ba₂Gd Ta O₆?BGTO?are selected as the host materials of the novel phosphors,doped with different activator ions,and the preparation process,luminescence characteristics and thermal stability are studied.1.Phosphors Ca Gd₄O₇:Eu³⁺with different concentrations are prepared.The excitation spectrum consists of broad band formed by the electron transition of the charge transfer band,and several spikes from the 4f-4f transition of Gd³⁺and Eu³⁺.The excitation peak of Gd³⁺overlaps with the charge transfer band of O^2--Eu³⁺,and there is an experiment of energy transferring from Gd³⁺to Eu³⁺.The emission spectrum shows red emission,and therefore the most important emission is the electric dipole transition caused by ⁵D₀?⁷F₂.The effect of doping Bi³⁺on the emission spectrum of CGO:Eu³⁺phosphors are studied.Fixed doping of 3 mol%Bi³⁺increases the Eu³⁺doping concentration,is effectively excited by near ultraviolet light,and the luminous intensity at 611 nm is enhanced.2.Phosphors CGO:Sm³⁺,CGO:Dy³⁺,CGO:Tb³⁺are prepared,and their photoluminescence is studied respectively.The luminescence of CGO:Sm³⁺phosphors originates from the transition in the 4f shell of Sm³⁺,and the emission at 653 nm is the strongest,which is derived from the excitation level of ⁴G_5/2.With the increase of Dy³⁺concentration,the emission intensity of CGO:Dy³⁺phosphors change from blue to yellow areas,and the color is adjustable.The excitation spectrum of CGO:Tb³⁺phosphors show that there is an excitation broadband in the ultraviolet region,which overlaps with the excitation band of Gd³⁺,and the emission spectrum shows effective green emission.3.Ba₂Gd Ta O₆:Eu³⁺phosphors with different concentrations are prepared.The structure is tetragonal and has obvious absorption in the ultraviolet region.Comparison withCaGd₄O₇:Eu³⁺shows that the substitution of?Ta O₃?^-to?Gd O₂?^-introduces the charge transport band of Ta-O,which enhances the absorption intensity in the ultraviolet region.Red light emission is observed,mainly from the magnetic dipole transition of Eu³⁺?⁵D₀?⁷F₁?.Different concentrations of BGTO:Mn⁴⁺phosphors are prepared,and a strong dark red emission band appeared at 674 nm.When the Mn⁴⁺doping concentration is 1 mol%,the emission intensity reaches the maximum.