Study On Luminescence Properties Of Special Valence State Ion Doped Phosphors

Due to special performance of phosphors doped with special valence state ions, thesephosphors are promising to be used to resolve some problems in the human society, such asglobal energy crisis, environmental pollution, war and peace, information and communication,health and medical treatment etc. Therefore, researchers are interested in the study onphosphors doped with special valence state ions in recent years.In this dissertation, we introduced the research developments on phosphors doped withspecial valence state ions, their luminescence properties, special performance and applicationsat first. Then we introduced the preparation of phosphors doped with special valence stateions, studied their luminescence properties via modern analysis techniques and discussed theirapplications in different fields. The research results in the dissertation can be summarized asfollow:（1） Bi₅（AlCl₄）₃crystal was prepared in the200³60℃region under anhydrousanaerobic conditions using melting salt （AlCl₃-NaCl） as reaction media. Optimum synthesisconditions of Bi₅（AlCl₄）₃crystal were investigated. Broadband near-to-mid infrared（NIR-MIR） photoluminescence centering at¹700nm with full width at half maximum（FWHM）⁷00nm at room temperature, in the range of1000³000nm was observed fromBi₅（AlCl₄）₃crystal due to a single type of Bi₅³⁺luminescent center in Bi₅（AlCl₄）₃crystal. Wehave investigated the influencing factor of luminescence of Bi₅（AlCl₄）₃crystal, compared theluminescence properties with these of the glasses doped with Bi ion, and discussed theluminous mechanism of Bi₅³⁺in Bi₅（AlCl₄）₃crystal based on the configurational coordinationdiagram. Bi₅（AlCl₄）₃crystal may have application in environment, laser, communication,national defense and medical treatment fields.（2） Due to rigorous experiment conditions for preparation of Bi₅（AlCl₄）₃crystal such ashigh temperature etc, Bi₅（GaCl₄）₃crystal was prepared at room temperature under anhydrousanaerobic conditions using organic solvent （such as benzene etc） as reaction media. Optimumsynthesis conditions of Bi₅（GaCl₄）₃crystal were investigated. Superbroad NIR-MIRphotoluminescence centering at¹835nm with full width at half maximum （FWHM）⁸00nm at room temperature, in the range of1000to3000nm was observed from Bi₅（GaCl₄）₃crystal due to a single type of Bi₅³⁺luminescence center in Bi₅（GaCl₄）₃crystal. We haveinvestigated the influencing factors of luminescence of Bi₅（GaCl₄）₃crystal and discussed theluminous mechanism of Bi₅³⁺in Bi₅（GaCl₄）₃crystal. Bi₅（GaCl₄）₃crystal may have applicationin environment, laser, communication, national defense and medical treatment fields. （3） Mn ions-doped BaSO₄crystal was prepared in the650⁷50℃region in air usingmelting salt （KCl-NaCl） as reaction media. Broadband near infrared （NIR） luminescence wasobserved. Optimum synthesis conditions of Mn ions-doped BaSO₄crystal were investigated.The concomitant Mn⁵⁺and Mn⁶⁺ions in the Mn ions-doped BaSO₄crystal were confirmed.NIR luminescence was observed from Mn⁵⁺ion in Mn ions-doped BaSO₄crystal centering at¹183nm with full width at half maximum （FWHM）⁵0nm at room temperature, spanningthe spectral range of1100to1400nm. NIR luminescence was observed from Mn⁶⁺ion in Mnions-doped BaSO₄crystal centering at¹060nm with FWHM of¹50nm at roomtemperature, in the range of850to1500nm. We have investigated the influencing factor ofluminescence of Mn ions-doped BaSO₄crystal and observed the energy transfer betweenMn⁵⁺and Mn⁶⁺ions in Mn ions-doped BaSO₄crystal according to time resolvedluminescence spectra. In addition, Mn⁶⁺ion-doped BaSO₄crystal was also prepared. Mnions-doped BaSO₄crystal may have application in laser and national defense fields.（4） BaSO₄:Bi²⁺red emission phosphor was synthesized in air via solid state reactionmethod. Optimum synthesis conditions of BaSO₄:Bi²⁺phosphors were investigated. Theemission band peaking at⁶27nm in the range of550to720nm with FWHM of⁵0nm ofBaSO₄:Bi²⁺excited at452nm was observed at room temperature. We have investigated theinfluencing factor of luminescence of BaSO₄:Bi²⁺phosphor and confirmed that Bi²⁺ion isonly luminescent center. White light-emitting diode （W-LED） was fabricated by using epoxyresin, a blend composition BaSO₄:Bi²⁺and Y3Al5O12:Ce3+（YAG:Ce3+） phosphors pumpedwith a455nm blue LED chip. The white LED shows chromaticity coordinates （x=0.3086，y=0.2902）, Ra value78and CCT （7256K）. BaSO₄:Bi²⁺red emission phosphor may haveapplication in W-LED fields.（5） Sr₂MgAl₂₂O₃₆:Mn⁴⁺red emission phosphor was synthesized in air via solid statereaction method. Optimum synthesis conditions of Sr42MgAl22O36:Mn+phosphors wereinvestigated. The emission band peaking at⁶58nm in the range of620to750nm withFWHM is⁵0nm of Sr4+2MgAl22O36:Mnexcited at397nm was observed at roomtemperature. We have investigated the influencing factor of luminescence ofSr₂MgAl₂₂O₃₆:Mn⁴⁺phosphor and confirmed that Mn⁴⁺ion is only luminescent center. Whitelight-emitting diode （W-LED） was fabricated by using epoxy resin, a blend compositionSr₂MgAl₂₂O₃₆:Mn⁴⁺and （Sr, Ba）22SiO4:Eu+phosphors pumped with a397nm near ultraviolet（UV） LED chip. The white LED shows chromaticity coordinates （x=0.3314，y=0.3211）, Ravalue62.2and CCT （5545K）. Sr₂MgAl₂₂O₃₆:Mn⁴⁺red emission phosphor may have application in W-LED fields.（6） SrMgAl₄+xO₁₇±δ: yMnred emission composite phosphor was synthesized in air viasolid state reaction method. Optimum synthesis conditions of SrMgAl_x4+xO_17±δ:yMn⁴⁺compositephosphors were investigated. The emission band peaking at⁶57nm in the range of620to750nm with FWHM of⁵0nm of SrMgAl_xO₁₇±δ: yMn⁴⁺excited at397nm was observed atroom temperature. Two concomitant crystalline phases, i.e., SrMaAl10O17and Al₂O₃phases inSrMgAl4xO17±δ:yMn+composite phosphors were observed. Energy transfer was observedbetween Mn⁴⁺-doped in SrMgAl4+10O17and Mn-doped in Al₂O₃phases by using time resolvedluminescence spectra. The emission intensity of SrMgAl_xO₁₇±δ:yMn⁴⁺composite phosphorchanged with changing Al₂O₃content, and confirmed that Mn⁴⁺ion is only luminescent center.Fluorescent lifetime and quantum efficiency increased with increasing Al₂O₃content.W-LEDs were demonstrated by using epoxy resin, a phosphors blend compositionSrMgAl_xO₁₇±δ:1.2Mn⁴⁺and （Sr, Ba）2SiO₄:Eu2+phosphors pumped with a397nm nearUV-chip. The white LED shows chromaticity coordinates （x=0.3304，y=0.3201）, Ra value65.2and CCT （5445K）. SrMgAl_xO₁₇±δ: yMn⁴⁺composite phosphor may have application inW-LED fields.（7） Optically active emission centers in Bi-doped luminescent materials, especially forNIR emission, remains disputed due to the large number of possible valence states such asBi3+, Bi²⁺, Bi²⁺02, Bi⁺, Bi, Bi⁵⁺and Bi₅³⁺etc and weak stability of Bi valence states in varioushosts. We disscussed the optically active NIR emission centers in Bi-doped oxide glasses. Weprepared Bi@SiO₂, MF₂:Bi （M=Ba and Sr）, MgF₂:V and ZnS:Co via various methods, andfound some emission band in the mid luminescence region with Bi-doped Bi2O3-GeO2glassreported by jiang et al. We concluded that the emission is not result from Bi active centers inthe oxide matrix but due to the selective atmospheric absorption of thermal radiation inducedby the laser irradiation. The research result is helpful for clarifying the optically active NIRemission center in Bi-doped luminescent materials..（8） RF₂:Bi（R=Ca and Sr）phosphor was synthesized in air via solid state reactionmethod. Optimum synthesis conditions of RF₂:B（iR=Ca and Sr）phosphor were investigated.The emission band peaking at⁵50nm in the range of380to800nm of CaF2:Bi phosphorexcited at²60nm was observed, and the emission band peaking at⁶00nm in the range of400to810nm of SrF2:Bi phosphor excited at²60nm was observed. Optically activeemission centers in RF₂:Bi（R=Ca and Sr）phosphor is Bi²⁺and the excitation and emissionbands of RF₂:B（iR=Ca and Sr）phosphor can be assigned to2P221/2S1/2andP3/2（1）2P1/2 transition of Bi²⁺ions, respectively. The research results are of reference value for disigningin Bi-doped luminescent materials.Finally, we provided a discussion and summary of the main points of the dissertation,and described the application prospect of phosphors doped with special valence state ions invarious fields.