Design And Synthesis Of Novel Phosphor Phosphors By Regulating Eu Valence

White LEDs have been widely used in various lighting fields due to their low energy consumption,high luminous efficiency,and long life.Therefore,with the rapid development of the lighting field,the requirements for white LEDs are becoming higher and higher.In order to improve the luminous performance of phosphors and better apply them to white LEDs,experts and scholars have proposed many new strategies.Among them,the control of the valence state of Eu ions is one of the important strategies,that is,the spectral control of the phosphor is achieved by the valence state control of Eu ions.In this paper,three kinds of phosphors known as Ba₃P₄O₁₃:0.06Eu²⁺,NaBaPO₄:0.03Eu²⁺,Sr₃P₄O₁₃:0.06Eu²⁺are synthesized by high-temperature solid-phase method.On this basis,through the substitution of cation pairs,the valence state of Eu is controlled in the phosphor,and then the phosphor spectrum control is realized.The content of this article is as follows:?1?The ion pair[Na⁺-La³⁺]replaces the ion pair[Ba²⁺-Ba²⁺].At this point,Na⁺acts as a charge compensator,so that Eu²⁺and Eu³⁺coexist in the Ba_2.94-2xLa_x Na_xP₄O₁₃:0.06Eu phosphor.The Eu²⁺/Eu³⁺ratio can be adjusted by adjusting the amount of substitution to achieve spectral regulation.Mapping and EDS characterization of the phosphor particles show that Ba,P,O,Na,La,and Eu are evenly distributed in the phosphor particles.XPS data further proved that Eu³⁺appeared in the sample because Eu²⁺was partially reduced.The excitation peak of Eu²⁺is wideband excitation of 250-420 nm,the excitation peak of Eu³⁺is narrowband excitation of 300-400 nm,and the strongest excitation peak is at 394 nm.The emission peak of Eu²⁺is a broadband blue emission peak at 400-620 nm,and its maximum emission wavelength is at 447 nm.The emission peak of Eu³⁺is a series of narrow-band red light emission peaks at 570-720 nm,and its maximum emission wavelength is at 587 nm.In the emission spectrum under 394 nm excitation,with the increase of[Na⁺-La³⁺]ion contrast ratio,the emission peak intensity of Eu²⁺gradually decreases,the intensity of Eu³⁺emission peak gradually increases,the ratio of Eu²⁺/Eu³⁺gradually decreases,and the emission color gradually changes from Blue light turns into white light and then into red light.The above research shows that in the Ba₃P₄O₁₃ system,by controlling the ratio of Eu²⁺/Eu³⁺to adjust the spectrum,white light emission can be achieved.?2?A series of Ba_0.97-2xLa_x Na_1+x+x PO₄:0.03Eu phosphors were synthesized by high-temperature solid-phase method under CO reducing atmosphere,and the ion pair[Na²⁺-La³⁺]replaced the ion pair[Ba²⁺-Ba²⁺],which was Eu³⁺Provide sites so that Eu³⁺is partially reduced to Eu²⁺,thereby achieving Eu²⁺/Eu³⁺coexistence in Ba_0.97-2x.97-2x La_xNa_1+x+x PO₄ matrix.By adjusting the substitution amount of[Na²⁺-La³⁺]to[Ba²⁺-Ba²⁺],the ratio of Eu²⁺/Eu³⁺can be adjusted,and then the emission spectrum of the phosphor can be adjusted.The excitation spectrum of Eu²⁺is broadband excitation at 250-420 nm,which can be effectively excited by near ultraviolet LED chips.The excitation peak of Eu³⁺is narrow-band excitation at 300-400 nm,and its maximum excitation wavelength is at 394 nm.The emission peak of Eu²⁺is a broadband blue emission peak at 400-620 nm,and its maximum emission wavelength is at 436 nm.The emission peak of Eu³⁺is a series of narrow-band red light emission peaks at 570-720 nm,and its maximum emission wavelength is at 615nm.The emission spectrum under excitation at 394 nm,with the increase of the concentration of the doped[Na²⁺-La³⁺]ion pair,the intensity of the emission peak of Eu²⁺gradually decreases,the intensity of the emission peak of Eu³⁺gradually increases,and the ratio of Eu²⁺/Eu³⁺gradually decreases.The luminescence of the powder changes from blue to blue-violet to purple,which realizes the spectrum regulation.Because the phosphor lacks the green component,Tb³⁺ions were selected as co-doped ions,and Ba_0.47La_0.25-yNa_1.25PO₄:0.03Eu,yTb³⁺phosphors were synthesized.EDS characterization showed Ba,Na,P,O,La,Eu and Tb are evenly distributed in the phosphor particles.The excitation peak of Tb³⁺ions is narrow-band excitation at 300-400 nm,and its maximum excitation wavelength is at 380 nm.The emission peaks of Tb³⁺ions are a series of narrow-band emission peaks at 480-650nm,and their maximum emission wavelength is at 544 nm.And there is energy transfer between Eu²⁺,Eu³⁺and Tb³⁺ions.With the increase of Tb³⁺concentration,the green light emission of the phosphor is increased,and finally the white light emission of the phosphor is realized.?3?Sr_2.94-2xLa_xNa_xP₄O₁₃:0.06Eu phosphors were prepared by traditional high-temperature solid-phase method under the reducing atmosphere of CO.The ion pair[Na⁺-La³⁺]replaces the ion pair[Sr²⁺-Sr²⁺]to provide sites for Eu³⁺,so Eu²⁺and Eu³⁺coexist in Sr_2.94-2x.94-2x La_xNa_xP₄O₁₃:0.06Eu phosphor.The ratio of Eu²⁺/Eu³⁺can be adjusted by adjusting the amount of[Na⁺-La³⁺],so the spectrum can be adjusted.In the as-prepared Sr_3-xP₄O₁₃:xEu²⁺phosphor,the quenching concentration of Eu²⁺is of6.0 mol%.The concentration quenching mechanism can be explained by the electronic dipole-dipole interaction mechanism.For the Sr_2.94-2xLa_xNa_xP₄O₁₃:0.06Eu phosphors,the excitation peaks of Eu³⁺are a series of narrow-band excitation peaks at 300-400 nm with the maximum excitation wavelength of 394 nm.Under the excitation of 394 nm,the emission peak of Eu²⁺is a broadband blue emission peak from 400 to 620 nm with the maximum emission wavelength of 418 nm,while the emission peak of Eu³⁺is a series of narrow-band red emission peaks at 570-720 nm with the maximum emission wavelength of 593 nm.As the substitution amount of[Na⁺-La³⁺]increases,the doping ratio of Eu²⁺/Eu³⁺changes,and the luminescent color of the phosphor gradually changes from blue to red light.