Study On Luminescence Properties Of Tiansition Metal Ion Mn⁴⁺and Rare Earth Ion Tb³⁺in Bazn_1.06al_9.94o₁₇Matrix

With the rapid development of LED(Light emitting diode)technology,the application of LED is also more extensive.In recent years,the application in the direction of agricultural lighting has also been promoted.It is well known that photosynthesis of plants requires various pigments,while the pigments have different light absorbing capacities for different wavelengths.Chlorophyll mainly absorbs blue light near 450 nm and deep red light near 660 nm.The Mn4+ions doped phosphor usually emits red light between 650 nm-700 nm,which is just enough to meet the red light required for plant growth.Therefore,the study of Mn4+ions has received extensive attention in recent years.Tb3+ions are typical green light emission,which are applied to the green phosphor in the three primary color phosphors required for the preparation of white LEDs.Co-doping Tb3+ ions with other ions to improve the luminous efficiency of Tb3+ions,contribute to the application of Tb3+ions green phosphor.Phosphors of BaZn1.O6Al9,94O17:Mrn4+,BaZn1.06Al9.94O17:Tb3+and BaZn1.06-Al9.94O17:Tb3+,Bi3+were prepared by high temperature solid phase method.The structure of the samples were examined with X-ray powder diffractometer.Study the luminescent properties by analyzing the excitation and emission spectra of the samples.The variable temperature spectrum of the samples is used to characterize the thermal stability.The structure of BaZn1.06Al9.94O17 did not change with doped of Mn4+,Tb3+and Bi3+ions according to XRD.The excitation spectrum of BaZ1n1.06Al9.94O17 Mn4+phosphor shows a strong broadband and two weak bands in the range of 200 nm-500 nm.The strong absorption band centered at 295 nm due to the overlap of the CT(charge transition)of the 02-to Mn4+and the 4A2?4T1transitions of the Mn4+ion.The two weak excitation peaks at 399 nm and 450 nm are due to the 4A2?2T2 and 4A2?4T2 transitions of the Mn4+ions,respectively.The emission spectrum of BaZn1.06Al9.94O17:Mn4+phosphor exhibits deep red emission peak at 665 nm,which belongs to the 2E?4A2 energy level transition of Mn4+ion.The wavelength of the emission peak is consistent with the light wavelength of the chlorophyll absorption,which can be applied to the field of plant illumination LED.With increasing the concentration of Mn4+ions,the emission intensity of BaZn-1.06Al9.94O17:Mn4+increased,reached a maximum at x=0.015 mol%,and then decreases due to concentration quenching.By analyzing the temperature-variation spectrum of the phosphor,the activation energy of the sample was calculated to be 0.441 eV,which is larger than the activation energy of the commercial phosphor CaAlSiN3:Eu2+(? E=0.2 eV),indicating that BaZn1.06Al9.94O17:M4+phosphor has good thermal stability.The excitation spectrum of BaZn1.06Al9.94O17:Tb3+phosphors shows a strong excitation broadband in the range of 200 nm-230 nm,and is centered at 210 nm,which is due to the 4f?5d transition of Tb3+ ions.The small weak absorption peaks near 350 nm are due to the transition of 4f?4f of the Tb3+ions.The emission spectrum of BaZn1.06Al9.94O17:Tb3+shows multiple emission peaks.The strongest emission peak of this sample is located at 544 nm,due to the 5D4?7F5 energy level transition of Tb3+ions,the emission peaks at 488nm,584nm and 623 nm due to 5D4?7F6?5D4?7F4?5D4?7F3 energy level transition of Tb3+ions,respectively.After the Bi3+ ions are co-doped in BaZn1.06Al9.94O17:Tb3+phosphor,the luminescence intensity of the sample is significantly increased,and the excitation band is red-shifted.This is due to the energy conversion of Bi3+to Tb3+.When the concentration of Bi3+is x=0.25 mol%,the excitation intensity enhanced 5.7 times.