Study Of The Synthesis And Luminescent Properties Of Bi³⁺ And Several Rare Earth Ions Doped New Optical Materials

Long-lasting phosphorescence?LLP?is the phenomenon encountered in materials which make them glow in the dark after the end of an excitation with UV or visible light.Accordingly,emitting ions and proper hosts with applicable defects are required to obtain excellent long-lasting phosphors.Phosphor as the main component of pc-WLEDs obtained great attention and had become a hotpot.However,the phosphors which can meet the requirements of commercial WLEDs are rare.Thus,it is of great value to develop novel phosphors which can be efficiently excited by UV or blue light.In the dissertation,we prepared a series of novel long-lasting phosphorescence and white LED phosphors by solid state reaction and investigated their crystal structure,luminescence properties,long-lasting properties and mechanism in detail.The main contents are listed as below:1.We synthesized a new long-lasting phosphor Mg₂SnO₄:Bi³⁺by traditional high-temperature solid-state reaction method.The results show that the phosphor can exhibit blue emission under UV light excitation.After ceasing the excitation,blue phosphorescence can be observed.For the optimal phosphor its blue phosphorescence could be observed by human naked eyes in the dark even after 3 hours.At last,a feasible long-lasting mechanism of Mg₂SnO₄:Bi³⁺was proposed and discussed.2.A novel orange-red emitting Ba₃Y₄O₉:Sm³⁺phosphors were prepared by a high temperature solid-state reaction in air.The results show that Ba₃Y₄O₉:Sm³⁺can be effectively excited under 410 nm.In addition,the effect of Sm³⁺ion concentration on the luminescence intensity was discussed,the optimal concentration sample and the energy transfer mechanism was discussed.The temperature-dependent study shows that this phosphor has excellent luminescence thermal-stability.The experimental data indicate Ba₃Y₄O₉:Sm³⁺phosphor may be promising as an orange-red emitting phosphor for white light emitting diodes.3.We synthesized a new phosphor Ba₃Y_4-xO₉:xDy³⁺by traditional high-temperature solid-state reaction method characterized its structure and luminescence properties using X-ray powder diffraction,photoluminescence spectra?PL?and fluorescence decay time.The results indicate that Ba₃Y_4-xO₉:xDy³⁺can be effectively stimulated by near ultraviolet light of 300 nm⁴00 nm.The chromaticity coordinates of Ba₃Y₄O₉:Dy³⁺phosphors were measured,which were in the yellow region and have good thermal stability.4.We synthesized a new near-infrared luminescent phosphor Ba₃Y₄O₉:RE³⁺(RE³⁺=Ho³⁺?Er³⁺)by traditional high-temperature solid-state reaction method.The results indicate that Ba₃Y₄O₉:RE³⁺(RE³⁺=Ho³⁺?Er³⁺)series of samples can emit light in the near infrared region and show sharp green light emission under light excitation.The experimental data indicate Ba₃Y₄O₉:RE³⁺(RE³⁺=Ho³⁺?Er³⁺)may be promising infrared luminescent material.