This paper reports the preparation of yttrium oxide(Y_(2)O_(3))doped with various concentrations of Er^(3+)using high temperature synthesis method.Photoluminescence(PL)emission spectra of the samples were recorded at ...This paper reports the preparation of yttrium oxide(Y_(2)O_(3))doped with various concentrations of Er^(3+)using high temperature synthesis method.Photoluminescence(PL)emission spectra of the samples were recorded at an excitation of 980 nm laser source.Two prominent peaks centered at 484 nm and 574 nm were found and attributed to the^(2)P3/2→^(4)I_(11/2)and^(4)S_(3/2)→^(4)I_(15/2),respectively.The sample with 2.5 mol%of Er^(3+)provided the optimum intensity in emission spectra.The sample with optimum PL emission was investigated for its thermoluminescence(TL)glow curve exhibited the second order kinetics.The peak TL intensity was found around 236°C,i.e.,towards high temperature which supports the fact of formation of deeper traps.Therefore,the material taken may be regarded as a good candidate for light emitting diode(LED)applications.展开更多
Cr^(3+)-activated phosphors have attracted significant attention for their tunable emission,spanning narrow-band red to broadband near-infrared(NIR)luminescence,depending on the crystal field environment.Here,we repor...Cr^(3+)-activated phosphors have attracted significant attention for their tunable emission,spanning narrow-band red to broadband near-infrared(NIR)luminescence,depending on the crystal field environment.Here,we report the realization of wideband NIR emission in Cr^(3+)-doped GaScO_(3)(GaScO_(3):Cr^(3+))phosphors with perovskite structure.The phosphors were synthesized by traditional solid-state reaction method.The first-principles calculations were conducted and the results demonstrate that the octahedral[GaO_(6)]sites exhibit relatively weak crystal field strength(Dq/B≈2.2),facilitating efficient spin-allowed transitions of Cr^(3+)from the^(4)T_(2)state to the^(4)A_(2)state.The photoluminescence spectroscopy revealed an exceptionally broad NIR emission band from a range of 700 nm-1200 nm with full width at half maximum(FWHM)of 145 nm under 465-nm excitation.Overall,these results highlight the viability of GaScO_(3):Cr^(3+)as a highly promising material for wideband NIR applications.展开更多
To meet the high demands of modern technology for temperature sensors,Lu_(2)WO_(6):Sm^(3+)self-activated phosphors were selected to design four-mode optical thermometers.A comprehensive investigation was conducted on ...To meet the high demands of modern technology for temperature sensors,Lu_(2)WO_(6):Sm^(3+)self-activated phosphors were selected to design four-mode optical thermometers.A comprehensive investigation was conducted on the synthetic method,structural and luminescent characteristics,and energy transfer mechanism([WO6]6-→Sm^(3+)). Due to the different temperature responses of two emission centers([WO6]6-and Sm^(3+)),the temperature sensing capability of Lu_(2)WO_(6):Sm^(3+)phosphors was studied.Fluorescence intensity(FI),fluorescence intensity ratio(FIR),Commission Internationale de L'Eclairage coordinates and excitation intensity ratio are the four modes for temperature sensing,and their maximum relative sensitivities are 2.62%/K(350 K),2.06%/K(320 K),0.67%/K(329 K) and 2.42%/K(303 K),respectively.Furthermore,within 303-483 K temperature range,the relative sensitivities based on FI and FIR are bigger than 1.67%/K and 1.16%/K,respectively.Our findings suggest that Lu_(2)WO_(6):Sm^(3+)phosphors with four temperature measurement modes might be applied in multi-mode self-calibration optical thermometers.展开更多
Cr^(3+)-activated spinel-type phosphors have great potential in different application scenes due to their unique sharp and far-red(FR)emission.However,the multi-functionalization of these phosphors is still limited by...Cr^(3+)-activated spinel-type phosphors have great potential in different application scenes due to their unique sharp and far-red(FR)emission.However,the multi-functionalization of these phosphors is still limited by their unsatisfied comprehensive properties.Herein,a simple composition engineering was used to explore versatile phosphors,using Ga^(3+)to substitute Al^(3+)to improve the optical performances of spinel LiAl5-xGa_(x)O_(8):Cr^(3+).The substitution of Ga^(3+)evidently affects the crystal field environment of Cr^(3+)and further accounts for the luminescence optimization.Using the optimized phosphor,two sensitive thermometers based on fluorescence intensity ratio(FIR)technique were explored on account of the different temperature dependencies of^(4)T_(2)→^(4)A_(2)and2E→^(4)A_(2)emission and of R2and R1emission.The maximum relative sensitivity Sr are 1.29%/K at 323 K and 1.94%/K at 298 K,respectively,which are superior to that of the Ga^(3+)-unsubstituted one.Besides,the Ga^(3+)→Al^(3+)substitutions endow the resultant phosphors with larger atomic number(Zeff)and theoretical density,which is more conducive to improving X-ray-stimulated emission for X-ray detection.Finally,the potential applications of the developed phosphor are also reflected in plant growth and night vision surveillance,as it is shown to be capable of matching with the absorption of phytochrome PFRand visualizing objects in the dark.This contribution not only proves that the developed LiAl5-xGa_(x)O_(8):Cr^(3+)FR phosphors are promising versatile platforms,but also provides an essential guidance for designing more novel multi-functional materials.展开更多
Bifunctional applications in solid state lighting and optical thermometry are attractive in the optical field.Despite Eu^(3+)doped phosphors are widely used in white-LEDs,phosphors with high temperature sensitivity re...Bifunctional applications in solid state lighting and optical thermometry are attractive in the optical field.Despite Eu^(3+)doped phosphors are widely used in white-LEDs,phosphors with high temperature sensitivity remain rare.Herein,NaLnTe_(2)O_(7):Eu^(3+)(Ln=Y and Gd)phosphors were synthesized using a rapid microwave-assisted solidstate(MASS)method to fulfill these applications.Under 395 nm excitation,NaLnTe_(2)O_(7):Eu^(3+)exhibit the characteristic ^(5)D_(0)→^(7)F_(J)(J=1–4)transitions of Eu^(3+).Substituting Gd^(3+) for Y^(3+) enhances the luminescence by approximately 2.42 times.Structural analyses reveal that the improved luminescent properties are attributed to the more distorted and appropriate coordination environment in NaGdTe_(2)O_(7):Eu^(3+).Finally,white-LEDs using NaGdTe_(2)O_(7):Eu^(3+)as the red-component produce white light with high Ra of 89.Furthermore,the distinct thermal responses of the ^(5)D_(0)→^(7)F_(J) transitions enable NaLnTe_(2)O_(7):Eu^(3+)to function as temperature sensors via fluorescence intensity ratio(FIR)strategy.NaYTe_(2)O_(7):Eu^(3+)possesses the maximum relative/absolute sensitivity of 1.45%/15.93%K^(-1),whereas NaGdTe_(2)O_(7):Eu^(3+)achieves the maximum relative/absolute sensitivity of 1.53%/30.24% K^(-1).This work highlights the significance of cationic substitution in enhancing luminescent properties for multifunctional applications.展开更多
Er^(3+)-doped BaLaGaO_(4)green phosphors was synthesized through a high-temperature solid-state reaction technique.The phase structure and morphology test results of the phosphor indicate that the BaLaGaO_(4)material ...Er^(3+)-doped BaLaGaO_(4)green phosphors was synthesized through a high-temperature solid-state reaction technique.The phase structure and morphology test results of the phosphor indicate that the BaLaGaO_(4)material was successfully synthesized and Er^(3+)ions were successfully doped into the main lattice.This doping does change the basic structure of the crystal.BaLaGaO_(4):Er^(3+)phosphor exhibits bright green emission centered at 545 nm when excited by 381 nm ultraviolet light or 980 nm near-infrared light.The optimal doping concentration is found to be x=0.04.To quantify the temperature sensitivity of the phosphor,the fluorescence intensity ratio method was used.Within the temperature range of 298-473 K,the maximum relative sensitivities are 1.35%/K(298 K,381 nm)and 1.45%/K(298 K,980 nm),respectively.The maximum absolute sensitivities are 0.67%/K(473 K,381 nm)and 0.69%/K(473 K,980 nm),respectively.Finally,white light-emitting diodes(WLEDs)with a high colour index of Ra=82and a relatively low correlated colour temperature of CCT=5064 K are obtained by integrating the synthesized BaLaGaO_(4):0.04Er^(3+)green phosphor into warm WLEDs devices.These results suggest that Er^(3+)-activated BaLaGaO_(4)multifunctional phosphors hold considerable promise in the areas of optical temperature sensing and WLEDs phosphor conversion.展开更多
To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through...To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through solid reaction process.The crystal structure,up-conversion luminescence,energy transfer,thermal stability and optical temperature sensing performances were studied in detail.Under 980 nm laser excitation,the KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor exhibits distinctive emission bands of Ho^(3+)at545,660,and 755 nm,and excellent illuminant performance.Based on the thermally coupled levels(TCLs)of Ho^(3+),both the relative sensitivity(S_(r))and absolute sensitivity(S_(a))display similar change trends,with the highest values of 6.73%/K(@298 K)and 5.69%/K(@298 K),respectively.Furthermore,the highest Saof 13.90%/K(@623 K)and the ultimate Srof 0.62%/K(@298 K)are achieved based on non-TCLs of Ho^(3+).Therefore,KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor is a promising candidate for self-referenced optical thermometry.展开更多
A set of germanate garnet phosphors containing Tb^(3+)and Eu^(3+)were adequately synthesized using the high-temperature solid-state technique.The structural properties,photoluminescence characteristics,fluorescence li...A set of germanate garnet phosphors containing Tb^(3+)and Eu^(3+)were adequately synthesized using the high-temperature solid-state technique.The structural properties,photoluminescence characteristics,fluorescence lifetimes,and temperature-sensing capabilities of the phosphors were thoroughly investigated.X-ray diffraction confirms the crystalline structure of the phosphors,while photoluminescence spectra reveal a colour shift attributed to the trans fer of energy from Tb^(3+)to Eu^(3+)as the concentration of Eu^(3+)increases.The phosphors excited by UV light display a transition in colour from green to yellow,and subsequently to red,which can be used as a colour tunable phosphor in white light-emitting diode(w-LED) applications.As a novel temperature sensing material,the maximum relative sensitivity of Ca_(3)Sc_(2)Ge_(3)O_(12):Tb^(3+),Eu^(3+)phosphor is 0.1044 K-1(298 K),highlighting its potential for applications in temperature sensing.展开更多
Er^(3+)-and Tm^(3+)-doped Ca_(x)Sr_(2-x)Nb_(2)O_(7)(C_(x)S_(2-x)N,x=0.6,0.8,1,0,1.2,1,4) phosphors with layered pe rovskite structure were designed.These phosphors exhibit a dominant emission peak at 549 nm under980 n...Er^(3+)-and Tm^(3+)-doped Ca_(x)Sr_(2-x)Nb_(2)O_(7)(C_(x)S_(2-x)N,x=0.6,0.8,1,0,1.2,1,4) phosphors with layered pe rovskite structure were designed.These phosphors exhibit a dominant emission peak at 549 nm under980 nm laser excitation,attributed to the^(4)S_(3/2)→^(4)I_(15/2)transition.By increasing the content of Ca^(2+),the crystal field regulation of rare earth ions is realized and the luminescence enhancement is induced,which is manifested by the increase of^(2)H_(11/2),^(4)S_(3/2)→^(4)I_(15/2)emission.Furthermore,the temperature sensing sensitivities of C_(0.6)S_(1.4)N:Er,Tm and C_(0.6)S_(1.4)N:Er,Tm based on non-thermally coupled energy levels were studied.Finally,an anti-counterfeiting imprint was prepared using phosphors,which have high brightness and excellent photothermal stability.This work not only confirms that closer ionic radii substitution enables to increase the electronic density of states,improve the crystal field symmetry and enhance the luminescence,but also provides a promising phosphor system for temperature sensing and anti-counterfeiting applications,opening up new prospects in the optimization of the optical properties of phosphors.展开更多
Novel orange-red Sr_(2)GdSbO_(6):xEu^(3+)(x=0,0.05,0.1,0.2,0.3,0.4,0.5 and 0.6) phospho rs were successfully prepared by the traditional high-temperature solid-state method.The results of Rietveld refinement,energy di...Novel orange-red Sr_(2)GdSbO_(6):xEu^(3+)(x=0,0.05,0.1,0.2,0.3,0.4,0.5 and 0.6) phospho rs were successfully prepared by the traditional high-temperature solid-state method.The results of Rietveld refinement,energy dispersive spectroscopy(EDS) spectrum and elemental mapping demonstrate that Eu^(3+) successfully replaces the Gd^(3+) sites and distributes uniformly in the particles of phosphors.The luminescence properties of Sr_(2)GdSbO_(6):Eu_(3+)phosphors were investigated in detail.The emission spectra of the strongest emission peak is the ^(5)D_(0)→^(7)F_(1)(593 nm) transition,which can emit orange-red light under393 nm excitation.When the doping concentration of Eu3+ions is x=0.2,the luminescence intensity of the phosphors reaches the highest.The detailed mechanism of concentration quenching is attributed to dipole-dipole interaction.The thermal stability values of Sr_(2)GdSbO_(6):0.2Eu^(3+) phosphors are 87%,82% and114% under 393,467 and 527 nm excitations,respectively.The causes of the abnormal thermal quenching under 527 nm excitation were analyzed.Based on the abnormal thermal quenching under527 nm excitation,the optical thermometry properties of Sr_(2)GdSbO_(6):0.2Eu^(3+)phosphors were investigated by fluorescence intensity ratio(FIR) technique,and appreciable relative sensitivity was obtained.The results suggest that Sr_(2)GdSbO_(6):0.2Eu^(3+)phosphors can be potentially applied to w-LEDs and optical thermometers.展开更多
In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as...In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.展开更多
Dual-excitation and dual-emission Y_(4)GeO_(8):Bi^(3+),Sm^(3+)phosphors were manufactured by traditional solidphase sintering technique.The X-ray diffraction,morphology,photoluminescence,energy transfer process and te...Dual-excitation and dual-emission Y_(4)GeO_(8):Bi^(3+),Sm^(3+)phosphors were manufactured by traditional solidphase sintering technique.The X-ray diffraction,morphology,photoluminescence,energy transfer process and temperature sensing properties of Y_(4)GeO_(8):Bi^(3+),Sm^(3+)samples were comprehensively evaluated.The Y4GeO_(8):Bi^(3+),Sm^(3+)phosphors exhibit characteristic emissions of Bi^(3+)(^(3)P_(1)→^(1)S_(0)) and Sm^(3+)(^(4)G_(5/2)→^(6)H)under both 290 and 347 nm excitations.In fluorescence intensity ratio and Commission International de L'Eclairage coordinates modes,Y_(4)GeO_(8):Bi^(3+),Sm^(3+)samples present excellent temperature measurement performance.The maximum relative sensitivity(S_(r-max)) values of the former are 1.55%/K(460 K,290 nm excitation) and 0.82%/K(506 K,347 nm excitation).The S_(r-max)(x) values of the latter are 0.21 %/K(437 K,290 nm excitation) and 0.15%/K(513 K,347 nm excitation).These results illustrate that Y_(4)GeO_(8):Bi^(3+),Sm^(3+)phospho rs can be used as a candidate material for a dual-mode optical thermometer under dual-excitation.展开更多
Dy^(3+) and Lu^(3+) co-doped CaLaGa_(3)O_(7) phosphors were prepared via high-temperature solid-phase reaction.The electronic structures of LuxCaLa_(0.98-x)Ga_(3)O_(7) were investigated by the first-principles calcula...Dy^(3+) and Lu^(3+) co-doped CaLaGa_(3)O_(7) phosphors were prepared via high-temperature solid-phase reaction.The electronic structures of LuxCaLa_(0.98-x)Ga_(3)O_(7) were investigated by the first-principles calculations.The influence of Lu^(3+) on yellow light emission was studied using X-ray diffraction(XRD)and photoluminescence(PL) measurements.The XRD results indicate that compared to Dy^(3+):CaLaGa_(3)O_(7),the cell parameters of Dy^(3+):LuCaLaGa_(3)O_(7) tend to decrease,which is due to the smaller radius of Lu^(3+).When pumped by blue GaN laser diode(LD),the emission peaks of phosphors with different Lu^(3+)doping concentrations in the visible region are similar,with the strongest peak at 574 nm in the yellow light region,which is sensitive to human eyes.The optimal doping concentration of Lu^(3+) is confirmed to be1 at%,when all emission spectra and measured fluorescence lifetimes are taken into account.Moreover,the optimal phosphor composition Dy^(3+):Lu_(x)CaLa_(0.98-x)Ga_(3)O_(7)(x=0.01) has an internal quantum efficiency(IQE) of 46.94% and an external quantum efficiency(EQE) of 15.19%.Most notably,the prepared phosphor demonstrates excellent thermal stability and a high activation energy(0.203 eV).In addition,the International Illumination Commission color coordinates of the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7) phosphors are in the yellow light area.The above analysis indicates that the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7)(x=0.001)phosphor has promising application prospects in yellow light-emitting devices.展开更多
In this research,a series of Sm^(3+) doped CsLu(WO_(4))_(2) phosphors was prepared via high temperature solid phase technique to design new red phosphors and optical thermometric materials.Their structures,morphology,...In this research,a series of Sm^(3+) doped CsLu(WO_(4))_(2) phosphors was prepared via high temperature solid phase technique to design new red phosphors and optical thermometric materials.Their structures,morphology,band gap and luminescence properties were characterized by X-ray diffraction,scanning electron microscopy,diffuse reflection and luminescence spectra,respectively.Under UV excitation,CsLu(WO_(4))_(2) gives rise to a blue broad emission band between 350 and 700 nm,which stems from the ^(3)T_(1u)→^(1)A_(1g) transition of WO_(6)^(6-) groups.When Sm^(3+) is introduced into CsLu(WO_(4))_(2),energy transfer between WO_(6)^(6-) groups and Sm^(3+) ions takes place in CsLu(WO_(4))_(2):Sm^(3+)phosphors,and color-tunable luminescence from blue to red is realized by controlling the Sm^(3+) doping concentration.The energy transfer efficiency between WO_(6)^(6-) groups and Sm^(3+) ons was analyzed,and the energy transfer mechanism was determined to be dipole-dipole interactions.According to the temperature-dependent luminescence spectra,WO_(6)^(6-)groups and Sm^(3+)ions exhibit large discrepancy in thermal quenching rates,and thus the temperature sensing properties of CsLu(WO_(4))_(2):Sm^(3+) in the temperature range of 283-403 K were analyzed.Based on the framework of fluorescence intensity ratio theory,the basic optical thermometry parameters including absolute and relative sensitivity of CsLu(WO_(4))_(2):Sm^(3+) we re calculated and the results show that it has great potential for application in optical thermometry.展开更多
In this study,a single-doped phosphors yttrium aluminum garnet(Y_(3)Al_(5)O_(12),YAG):Ce^(3+),single-doped YAG:Sc^(3+),and double-doped phosphors YAG:Ce^(3+),Sc^(3+) were prepared by spark plasma sintering(SPS)(lower ...In this study,a single-doped phosphors yttrium aluminum garnet(Y_(3)Al_(5)O_(12),YAG):Ce^(3+),single-doped YAG:Sc^(3+),and double-doped phosphors YAG:Ce^(3+),Sc^(3+) were prepared by spark plasma sintering(SPS)(lower than 1 200℃).The characteristics of synthesized phosphors were determined using scanning electron microscopy(SEM),X-ray diffraction(XRD),and fluorescence spectroscopy.During SPS,the lattice structure of YAG was maintained by the added Ce^(3+) and Sc^(3+).The emission wavelength of YAG:Ce^(3+) prepared from SPS(425-700 nm) was wider compared to that of YAG:Ce^(3+) prepared from high-temperature solid-state reaction(HSSR)(500-700 nm).The incorporation of low-dose Sc^(3+) in YAG:Ce^(3+) moved the emission peak towards the short wavelength.展开更多
Photoluminescent materials,serving as optical probes,constitute a significant medium for reliable re-mote sensing of fundamental state parameters such as temperature and pressure.Herein,we report a novel Mn^(4+)-activ...Photoluminescent materials,serving as optical probes,constitute a significant medium for reliable re-mote sensing of fundamental state parameters such as temperature and pressure.Herein,we report a novel Mn^(4+)-activated perovskite-type La_(3) Mg2 SbO9 phosphor(LMS:Mn^(4+))for bifunctional application in both thermometry and manometry.Upon excitation with 341 nm,LMS:Mn^(4+)(0.7%Mn^(4+))emits a bright narrow-band red light peaking at 705 nm with an FWHM(full width at half maximum)of 32 nm.As a thermometer,when the temperature surpasses 298 K,non-radiative transitions from the ^(2)Eg excited state lead to a sharp decrease in decay lifetimes with increasing temperature.This allows for lifetime-based luminescence thermometry with a relative sensitivity of 2.52%K^(−1) at 391 K.Moreover,LMS:Mn^(4+)was processed into a temperature-sensing coating and its non-contact thermometry functionality was validated.In manometry applications,the LMS:Mn^(4+)probe experiences substantial pressure-dependent redshift with a sensitivity of 1.20 nm GPa^(−1) in the testing range of 9.48 GPa,which is about 3.3 times that of conventional ruby probes.Furthermore,its FWHM consistently remains below 37 nm,which con-tributes to a high reliability of pressure measurements.The above results indicate that the LMS:Mn^(4+)constitutes a promising bifunctional luminescence probe material in thermometry and manometry.展开更多
A red-emitting phosphor Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) with partial Al^(3+)/P^(5+) substitution on Si^(4+) was synthesized via a simple solid-state method,and the effects of the introduction of the M^(3+/5+)(M=Al,P)...A red-emitting phosphor Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) with partial Al^(3+)/P^(5+) substitution on Si^(4+) was synthesized via a simple solid-state method,and the effects of the introduction of the M^(3+/5+)(M=Al,P)ions on the crystal structure and photoluminescence performance of Ca_(2.91)Si_(2−x)M_(x)O_(7):0.09Eu^(3+) phosphors were investigated.The X-ray diffraction(XRD),energy-dispersive X-ray spectroscopy(EDS),and X-ray photoelectron spectroscopy(XPS)results revealed that the structure of Ca_(3)Si_(2)O_(7) remained the same after the introduction of Al^(3+) and P^(5+) ions.The characteristic emission of Eu^(3+)-doped Ca_(3)Si_(2−x)M_(x)O_(7) phosphors exhibited two main peaks at 617 nm(red)and 593 nm(orange)under excitation at 394 nm,which originated from the^(5)D_(0)→^(7)F_(2)and^(5)D_(0)→^(7)F_(1) electron transitions of Eu^(3+) ions.After the partial substitution of Al^(3+) and P^(5+),the red emission intensities of the Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) phosphors were significantly enhanced by 1.88-and 1.42-fold,respectively,which is attributed to the crystal-field effect around Eu^(3+).Meanwhile,the luminescence intensities of the Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+) and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) phosphors at 210℃ were 79.36%and 77.53%of those at 30°C,respectively,indicating their excellent thermal stability.Moreover,the as-prepared Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+)and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) red-emitting phosphors were combined with a near-ultraviolet chip of 395 nm to fabricate red-light-emitting diode(LED)and white(w)-LED devices with excellent chromaticity features.In summary,Al^(3+)/P^(5+)-substituted Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) can serve as red-emitting phosphors for applications in w-LEDs.展开更多
The blue-light-excitable phosphors play a crucial role in the high-performance white LEDs. Here, we report on two new Cu(Ⅰ) coordination network materials as yellow-emitting phosphors prepared by suitably expanded π...The blue-light-excitable phosphors play a crucial role in the high-performance white LEDs. Here, we report on two new Cu(Ⅰ) coordination network materials as yellow-emitting phosphors prepared by suitably expanded π-conjugated triazole ligands. Upon blue-light irradiation, these complexes exhibit efficient solid-state emission and enhanced photostability. Through incorporating the yellow phosphor and a commercial blue-green powder(BaSi_(2)N_(2)O_(2):Eu^(2+)) with a blue LED chip, the phosphor-converted LED devices display remarkable white emission properties. The experimental results demonstrate that the Cu(Ⅰ)coordination network materials function as promising blue-light excitable phosphors with great application potential for full-spectrum white LEDs.展开更多
Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband emissions.However,these materials generally have ...Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband emissions.However,these materials generally have too wide bandgaps and thus cannot be excited by blue light,which hinders their applications for efficient white light-emitting diodes(WLEDs).The key to achieving a blue-light-excitable 0D hybrid metal halide phosphor is to reduce the fundamental bandgap by rational chemical design.In this work,we report two designed hybrid copper(I)iodides,(Ph_(3)MeP)_(2)Cu_(4)I_(6)and(Cy_(3)MeP)_(2)Cu_(4)I_(6),as blue-light-excitable yellow phosphors with ultrabroadband emission.In these compounds,the[Cu_(4)I_(6)]^(2-)anion forms an I6 octahedron centered on a cationic Cu_(4)tetrahedron.The strong cation-cation bonding within the unique cationic Cu_(4)tetrahedra enables significantly lowered conduction band minimums and thus narrowed bandgaps,as compared to other reported hybrid copper(I)iodides.The ultrabroadband emission is attributed to the coexistence of free and self-trapped excitons.The WLED using the[Cu_(4)I_(6)]^(2-)anion-based single phosphor shows warm white light emission,with a high luminous efficiency of 65 Im W^(-1)and a high color rendering index of 88.This work provides strategies to design narrow-bandgap 0D hybrid metal halides and presents two first examples of blue-light-excitable 0D hybrid metal halide phosphors for efficient WLEDs.展开更多
Optical thermometry as an important local temperature-sensing technique,has received increasing attention in scientific and industrial areas.However,it is still a big challenge to develop luminescent materials with se...Optical thermometry as an important local temperature-sensing technique,has received increasing attention in scientific and industrial areas.However,it is still a big challenge to develop luminescent materials with self-activated dual-wavelength emissions toward high-sensitivity optical thermometers.Herein,a novel ratiometric thermometric strategy of Bi^(3+)-activated dual-wavelength emission band was realized in the same lattice position with two local electronic states of La_(3)Sb_(1-x)Ta_xO_(7):Bi^(3+)(0≤x≤1.0)materials based on the different temperature-dependent emission behaviors,benefiting from the highlysensitive and regulable emission to the coordination environment of Bi^(3+).The structural and spectral results demonstrate that the emission tremendously shifted from green to blue with 68 nm and the intensity was enhanced 2.6 times.Especially,the visual dual-wavelength emitting from two emission centers was presented by increasing the Ta^(5+)substitution concentration to 20%or 25%,mainly originating from the two local electronic states around the Bi^(3+)emission center.Significantly,the dual-wavelength with different thermal-quenching performance provided high-temperature sensitivity and good discrimination signals for optical thermometry in the range between 303 and 493 K.The maximum relative sensitivity reached 2.64%/K(La_(3)Sb_(0.8)Ta_(0.2)O_(7):0.04Bi^(3+)@383 K)and 1.91%/K(La_(3)Sb_(0.75)Ta_(0.25)O_(7):0.04Bi^(3+)@388 K).This work reveals a rational design strategy of different local electronic states around the singledoping multiple emission centers towards practical applications,such as luminescence thermometry and white LED lighting.展开更多
文摘This paper reports the preparation of yttrium oxide(Y_(2)O_(3))doped with various concentrations of Er^(3+)using high temperature synthesis method.Photoluminescence(PL)emission spectra of the samples were recorded at an excitation of 980 nm laser source.Two prominent peaks centered at 484 nm and 574 nm were found and attributed to the^(2)P3/2→^(4)I_(11/2)and^(4)S_(3/2)→^(4)I_(15/2),respectively.The sample with 2.5 mol%of Er^(3+)provided the optimum intensity in emission spectra.The sample with optimum PL emission was investigated for its thermoluminescence(TL)glow curve exhibited the second order kinetics.The peak TL intensity was found around 236°C,i.e.,towards high temperature which supports the fact of formation of deeper traps.Therefore,the material taken may be regarded as a good candidate for light emitting diode(LED)applications.
基金supported by the Natural Science Research Project of Anhui Provincial Education Department for Excellent Young Scholars(Grant No.2024AH030007)the National Natural Science Foundation of China(Grant No.52202001).
文摘Cr^(3+)-activated phosphors have attracted significant attention for their tunable emission,spanning narrow-band red to broadband near-infrared(NIR)luminescence,depending on the crystal field environment.Here,we report the realization of wideband NIR emission in Cr^(3+)-doped GaScO_(3)(GaScO_(3):Cr^(3+))phosphors with perovskite structure.The phosphors were synthesized by traditional solid-state reaction method.The first-principles calculations were conducted and the results demonstrate that the octahedral[GaO_(6)]sites exhibit relatively weak crystal field strength(Dq/B≈2.2),facilitating efficient spin-allowed transitions of Cr^(3+)from the^(4)T_(2)state to the^(4)A_(2)state.The photoluminescence spectroscopy revealed an exceptionally broad NIR emission band from a range of 700 nm-1200 nm with full width at half maximum(FWHM)of 145 nm under 465-nm excitation.Overall,these results highlight the viability of GaScO_(3):Cr^(3+)as a highly promising material for wideband NIR applications.
文摘To meet the high demands of modern technology for temperature sensors,Lu_(2)WO_(6):Sm^(3+)self-activated phosphors were selected to design four-mode optical thermometers.A comprehensive investigation was conducted on the synthetic method,structural and luminescent characteristics,and energy transfer mechanism([WO6]6-→Sm^(3+)). Due to the different temperature responses of two emission centers([WO6]6-and Sm^(3+)),the temperature sensing capability of Lu_(2)WO_(6):Sm^(3+)phosphors was studied.Fluorescence intensity(FI),fluorescence intensity ratio(FIR),Commission Internationale de L'Eclairage coordinates and excitation intensity ratio are the four modes for temperature sensing,and their maximum relative sensitivities are 2.62%/K(350 K),2.06%/K(320 K),0.67%/K(329 K) and 2.42%/K(303 K),respectively.Furthermore,within 303-483 K temperature range,the relative sensitivities based on FI and FIR are bigger than 1.67%/K and 1.16%/K,respectively.Our findings suggest that Lu_(2)WO_(6):Sm^(3+)phosphors with four temperature measurement modes might be applied in multi-mode self-calibration optical thermometers.
基金Project supported by the National Natural Science Foundation of China(52272143,51902063)the Guangdong Basic and Applied Basic Research Foundation(2023A1515010166,2023A1515010866,2021A1515110404)the Major Science and Technology Project of Jiangxi Province(20223AAE01003)。
文摘Cr^(3+)-activated spinel-type phosphors have great potential in different application scenes due to their unique sharp and far-red(FR)emission.However,the multi-functionalization of these phosphors is still limited by their unsatisfied comprehensive properties.Herein,a simple composition engineering was used to explore versatile phosphors,using Ga^(3+)to substitute Al^(3+)to improve the optical performances of spinel LiAl5-xGa_(x)O_(8):Cr^(3+).The substitution of Ga^(3+)evidently affects the crystal field environment of Cr^(3+)and further accounts for the luminescence optimization.Using the optimized phosphor,two sensitive thermometers based on fluorescence intensity ratio(FIR)technique were explored on account of the different temperature dependencies of^(4)T_(2)→^(4)A_(2)and2E→^(4)A_(2)emission and of R2and R1emission.The maximum relative sensitivity Sr are 1.29%/K at 323 K and 1.94%/K at 298 K,respectively,which are superior to that of the Ga^(3+)-unsubstituted one.Besides,the Ga^(3+)→Al^(3+)substitutions endow the resultant phosphors with larger atomic number(Zeff)and theoretical density,which is more conducive to improving X-ray-stimulated emission for X-ray detection.Finally,the potential applications of the developed phosphor are also reflected in plant growth and night vision surveillance,as it is shown to be capable of matching with the absorption of phytochrome PFRand visualizing objects in the dark.This contribution not only proves that the developed LiAl5-xGa_(x)O_(8):Cr^(3+)FR phosphors are promising versatile platforms,but also provides an essential guidance for designing more novel multi-functional materials.
基金financially supported by the Caiyun Postdoctoral Innovation Project(No.C615300504089)Yunnan Fundamental Research Project(No.202401AS070128)National Natural Science Foundation of China(No.22165031).
文摘Bifunctional applications in solid state lighting and optical thermometry are attractive in the optical field.Despite Eu^(3+)doped phosphors are widely used in white-LEDs,phosphors with high temperature sensitivity remain rare.Herein,NaLnTe_(2)O_(7):Eu^(3+)(Ln=Y and Gd)phosphors were synthesized using a rapid microwave-assisted solidstate(MASS)method to fulfill these applications.Under 395 nm excitation,NaLnTe_(2)O_(7):Eu^(3+)exhibit the characteristic ^(5)D_(0)→^(7)F_(J)(J=1–4)transitions of Eu^(3+).Substituting Gd^(3+) for Y^(3+) enhances the luminescence by approximately 2.42 times.Structural analyses reveal that the improved luminescent properties are attributed to the more distorted and appropriate coordination environment in NaGdTe_(2)O_(7):Eu^(3+).Finally,white-LEDs using NaGdTe_(2)O_(7):Eu^(3+)as the red-component produce white light with high Ra of 89.Furthermore,the distinct thermal responses of the ^(5)D_(0)→^(7)F_(J) transitions enable NaLnTe_(2)O_(7):Eu^(3+)to function as temperature sensors via fluorescence intensity ratio(FIR)strategy.NaYTe_(2)O_(7):Eu^(3+)possesses the maximum relative/absolute sensitivity of 1.45%/15.93%K^(-1),whereas NaGdTe_(2)O_(7):Eu^(3+)achieves the maximum relative/absolute sensitivity of 1.53%/30.24% K^(-1).This work highlights the significance of cationic substitution in enhancing luminescent properties for multifunctional applications.
基金supported by the National Natural Science Foundation of China(52403403)Guizhou Provincial Basic Research Program(Natural Science)(Qian ke he ji chu-ZK2024 YiBan 095)。
文摘Er^(3+)-doped BaLaGaO_(4)green phosphors was synthesized through a high-temperature solid-state reaction technique.The phase structure and morphology test results of the phosphor indicate that the BaLaGaO_(4)material was successfully synthesized and Er^(3+)ions were successfully doped into the main lattice.This doping does change the basic structure of the crystal.BaLaGaO_(4):Er^(3+)phosphor exhibits bright green emission centered at 545 nm when excited by 381 nm ultraviolet light or 980 nm near-infrared light.The optimal doping concentration is found to be x=0.04.To quantify the temperature sensitivity of the phosphor,the fluorescence intensity ratio method was used.Within the temperature range of 298-473 K,the maximum relative sensitivities are 1.35%/K(298 K,381 nm)and 1.45%/K(298 K,980 nm),respectively.The maximum absolute sensitivities are 0.67%/K(473 K,381 nm)and 0.69%/K(473 K,980 nm),respectively.Finally,white light-emitting diodes(WLEDs)with a high colour index of Ra=82and a relatively low correlated colour temperature of CCT=5064 K are obtained by integrating the synthesized BaLaGaO_(4):0.04Er^(3+)green phosphor into warm WLEDs devices.These results suggest that Er^(3+)-activated BaLaGaO_(4)multifunctional phosphors hold considerable promise in the areas of optical temperature sensing and WLEDs phosphor conversion.
基金supported by the National Natural Science Foundation of China(61865003)。
文摘To develop new up-conversion luminescent materials for non-contact optical thermometer with high sensitivity and temperature re solution,a battery of KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphors were fabricated through solid reaction process.The crystal structure,up-conversion luminescence,energy transfer,thermal stability and optical temperature sensing performances were studied in detail.Under 980 nm laser excitation,the KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor exhibits distinctive emission bands of Ho^(3+)at545,660,and 755 nm,and excellent illuminant performance.Based on the thermally coupled levels(TCLs)of Ho^(3+),both the relative sensitivity(S_(r))and absolute sensitivity(S_(a))display similar change trends,with the highest values of 6.73%/K(@298 K)and 5.69%/K(@298 K),respectively.Furthermore,the highest Saof 13.90%/K(@623 K)and the ultimate Srof 0.62%/K(@298 K)are achieved based on non-TCLs of Ho^(3+).Therefore,KBaGd(MoO_(4))_(3):Yb^(3+),Ho^(3+)phosphor is a promising candidate for self-referenced optical thermometry.
基金Project supported by the National Natural Science Foundation of China (52274273)。
文摘A set of germanate garnet phosphors containing Tb^(3+)and Eu^(3+)were adequately synthesized using the high-temperature solid-state technique.The structural properties,photoluminescence characteristics,fluorescence lifetimes,and temperature-sensing capabilities of the phosphors were thoroughly investigated.X-ray diffraction confirms the crystalline structure of the phosphors,while photoluminescence spectra reveal a colour shift attributed to the trans fer of energy from Tb^(3+)to Eu^(3+)as the concentration of Eu^(3+)increases.The phosphors excited by UV light display a transition in colour from green to yellow,and subsequently to red,which can be used as a colour tunable phosphor in white light-emitting diode(w-LED) applications.As a novel temperature sensing material,the maximum relative sensitivity of Ca_(3)Sc_(2)Ge_(3)O_(12):Tb^(3+),Eu^(3+)phosphor is 0.1044 K-1(298 K),highlighting its potential for applications in temperature sensing.
基金Project supported by the Science and Technology International Cooperation Project of Qinghai Province (2022-HZ-807)the Open Project Salt Lake Chemical Engineering Research Complex,Qinghai University (2023-DXSSZZ-04)。
文摘Er^(3+)-and Tm^(3+)-doped Ca_(x)Sr_(2-x)Nb_(2)O_(7)(C_(x)S_(2-x)N,x=0.6,0.8,1,0,1.2,1,4) phosphors with layered pe rovskite structure were designed.These phosphors exhibit a dominant emission peak at 549 nm under980 nm laser excitation,attributed to the^(4)S_(3/2)→^(4)I_(15/2)transition.By increasing the content of Ca^(2+),the crystal field regulation of rare earth ions is realized and the luminescence enhancement is induced,which is manifested by the increase of^(2)H_(11/2),^(4)S_(3/2)→^(4)I_(15/2)emission.Furthermore,the temperature sensing sensitivities of C_(0.6)S_(1.4)N:Er,Tm and C_(0.6)S_(1.4)N:Er,Tm based on non-thermally coupled energy levels were studied.Finally,an anti-counterfeiting imprint was prepared using phosphors,which have high brightness and excellent photothermal stability.This work not only confirms that closer ionic radii substitution enables to increase the electronic density of states,improve the crystal field symmetry and enhance the luminescence,but also provides a promising phosphor system for temperature sensing and anti-counterfeiting applications,opening up new prospects in the optimization of the optical properties of phosphors.
基金supported by the National Natural Science Foundation of China (52262020)Guizhou Provincial Department of Education Science and Technology Uprooted Talents Project ([2022] 085)+1 种基金Guizhou Provincial Department of Education Rolling Support for Provincial Universities Scientific Research Platform Team Project ([2022] 036)the Science and Technology Foundation of Guizhou Province (ZK [2021] 328)。
文摘Novel orange-red Sr_(2)GdSbO_(6):xEu^(3+)(x=0,0.05,0.1,0.2,0.3,0.4,0.5 and 0.6) phospho rs were successfully prepared by the traditional high-temperature solid-state method.The results of Rietveld refinement,energy dispersive spectroscopy(EDS) spectrum and elemental mapping demonstrate that Eu^(3+) successfully replaces the Gd^(3+) sites and distributes uniformly in the particles of phosphors.The luminescence properties of Sr_(2)GdSbO_(6):Eu_(3+)phosphors were investigated in detail.The emission spectra of the strongest emission peak is the ^(5)D_(0)→^(7)F_(1)(593 nm) transition,which can emit orange-red light under393 nm excitation.When the doping concentration of Eu3+ions is x=0.2,the luminescence intensity of the phosphors reaches the highest.The detailed mechanism of concentration quenching is attributed to dipole-dipole interaction.The thermal stability values of Sr_(2)GdSbO_(6):0.2Eu^(3+) phosphors are 87%,82% and114% under 393,467 and 527 nm excitations,respectively.The causes of the abnormal thermal quenching under 527 nm excitation were analyzed.Based on the abnormal thermal quenching under527 nm excitation,the optical thermometry properties of Sr_(2)GdSbO_(6):0.2Eu^(3+)phosphors were investigated by fluorescence intensity ratio(FIR) technique,and appreciable relative sensitivity was obtained.The results suggest that Sr_(2)GdSbO_(6):0.2Eu^(3+)phosphors can be potentially applied to w-LEDs and optical thermometers.
基金supported by the National Natural Science Foundation of China (52202001)Open Project of Advanced Laser Technology Laboratory of Anhui Province (AHL2021KF07)+1 种基金Major Science and Technology of Anhui Province(202203a05020002)University Natural Science Research Project of Anhui Province (KJ2021A0388)。
文摘In this work,a series of self-activated KYb(MoO_(4))_(2) phosphors with various x at% Er^(3+) doping concentrations(x=0.5,1,3,5,8,10,15) was synthesized by the solid-state reaction method.The phase structure of the as-prepared samples was analyzed by X-ray diffraction(XRD),XRD Rietveld refinement and Fourier transform infrared(FT-IR) spectroscopy.The as-prepared samples retain the orthorhombic structure with space group of Pbcn even Er^(3+) doping concentration up to 15 at%.High-purity upconversion(UC) green emission with green to red intensity ratio of 55 is observed from the as-prepared samples upon the excitation of 980 nm semiconductor laser and the optimum doping concentration of Er^(3+) ions in the self-activated KYb(MoO_(4))_(2) host is revealed as 3 at%.The strong green UC emission is confirmed as a two-photon process based on the power-dependent UC spectra.In addition,the fluorescence intensity ratios(FIRs) of the two thermally-coupled energy levels,namely ^(2)H_(11/2) and ^(4)S_(3/2).of Er^(3+) ions were investigated in the temperature region 300-570 K to evaluate the optical temperature sensor behavior of the sample.The maximum relative sensitivity(S_(R)) is determined to be 0.0069 K^(-1) at300 K and the absolute sensitivity(S_(A)) is determined to be 0.0126 K^(-1) at 300 K.The S_(A) of self-activated KYb(MoO_(4))2:Er^(3+)is almost twice that of traditional KY(MoO_(4))2:Er^(3+)/Yb^(3+)codoping phosphor.The results demonstrate that Er^(3+) ions doped self-activated KYb(MoO_(4))2 phosphor has promising application in visible display,trademark security and optical temperature sensors.
基金supported by the National Natural Science Foundation of China (11974315)。
文摘Dual-excitation and dual-emission Y_(4)GeO_(8):Bi^(3+),Sm^(3+)phosphors were manufactured by traditional solidphase sintering technique.The X-ray diffraction,morphology,photoluminescence,energy transfer process and temperature sensing properties of Y_(4)GeO_(8):Bi^(3+),Sm^(3+)samples were comprehensively evaluated.The Y4GeO_(8):Bi^(3+),Sm^(3+)phosphors exhibit characteristic emissions of Bi^(3+)(^(3)P_(1)→^(1)S_(0)) and Sm^(3+)(^(4)G_(5/2)→^(6)H)under both 290 and 347 nm excitations.In fluorescence intensity ratio and Commission International de L'Eclairage coordinates modes,Y_(4)GeO_(8):Bi^(3+),Sm^(3+)samples present excellent temperature measurement performance.The maximum relative sensitivity(S_(r-max)) values of the former are 1.55%/K(460 K,290 nm excitation) and 0.82%/K(506 K,347 nm excitation).The S_(r-max)(x) values of the latter are 0.21 %/K(437 K,290 nm excitation) and 0.15%/K(513 K,347 nm excitation).These results illustrate that Y_(4)GeO_(8):Bi^(3+),Sm^(3+)phospho rs can be used as a candidate material for a dual-mode optical thermometer under dual-excitation.
基金supported by the Shandong Provincial Natural Science Foundation (ZR2020QE034,ZR2021QF081)National Natural Science Foundation of China (11974304)Anhui Provincial Natural Science Foundation(2008085QA45,2008085QA49)。
文摘Dy^(3+) and Lu^(3+) co-doped CaLaGa_(3)O_(7) phosphors were prepared via high-temperature solid-phase reaction.The electronic structures of LuxCaLa_(0.98-x)Ga_(3)O_(7) were investigated by the first-principles calculations.The influence of Lu^(3+) on yellow light emission was studied using X-ray diffraction(XRD)and photoluminescence(PL) measurements.The XRD results indicate that compared to Dy^(3+):CaLaGa_(3)O_(7),the cell parameters of Dy^(3+):LuCaLaGa_(3)O_(7) tend to decrease,which is due to the smaller radius of Lu^(3+).When pumped by blue GaN laser diode(LD),the emission peaks of phosphors with different Lu^(3+)doping concentrations in the visible region are similar,with the strongest peak at 574 nm in the yellow light region,which is sensitive to human eyes.The optimal doping concentration of Lu^(3+) is confirmed to be1 at%,when all emission spectra and measured fluorescence lifetimes are taken into account.Moreover,the optimal phosphor composition Dy^(3+):Lu_(x)CaLa_(0.98-x)Ga_(3)O_(7)(x=0.01) has an internal quantum efficiency(IQE) of 46.94% and an external quantum efficiency(EQE) of 15.19%.Most notably,the prepared phosphor demonstrates excellent thermal stability and a high activation energy(0.203 eV).In addition,the International Illumination Commission color coordinates of the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7) phosphors are in the yellow light area.The above analysis indicates that the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7)(x=0.001)phosphor has promising application prospects in yellow light-emitting devices.
基金Project supported by the Natural Science Foundation (NSF)of Anhui Province (2108085MB53)the NSF for Distinguished Young Scholars of Anhui University (2022AH020087)University NSF of Anhui Province(KJ2020A0647)。
文摘In this research,a series of Sm^(3+) doped CsLu(WO_(4))_(2) phosphors was prepared via high temperature solid phase technique to design new red phosphors and optical thermometric materials.Their structures,morphology,band gap and luminescence properties were characterized by X-ray diffraction,scanning electron microscopy,diffuse reflection and luminescence spectra,respectively.Under UV excitation,CsLu(WO_(4))_(2) gives rise to a blue broad emission band between 350 and 700 nm,which stems from the ^(3)T_(1u)→^(1)A_(1g) transition of WO_(6)^(6-) groups.When Sm^(3+) is introduced into CsLu(WO_(4))_(2),energy transfer between WO_(6)^(6-) groups and Sm^(3+) ions takes place in CsLu(WO_(4))_(2):Sm^(3+)phosphors,and color-tunable luminescence from blue to red is realized by controlling the Sm^(3+) doping concentration.The energy transfer efficiency between WO_(6)^(6-) groups and Sm^(3+) ons was analyzed,and the energy transfer mechanism was determined to be dipole-dipole interactions.According to the temperature-dependent luminescence spectra,WO_(6)^(6-)groups and Sm^(3+)ions exhibit large discrepancy in thermal quenching rates,and thus the temperature sensing properties of CsLu(WO_(4))_(2):Sm^(3+) in the temperature range of 283-403 K were analyzed.Based on the framework of fluorescence intensity ratio theory,the basic optical thermometry parameters including absolute and relative sensitivity of CsLu(WO_(4))_(2):Sm^(3+) we re calculated and the results show that it has great potential for application in optical thermometry.
基金Funded by the Primary Research and Development Plan of Jiangsu Province(No.BE2016175)。
文摘In this study,a single-doped phosphors yttrium aluminum garnet(Y_(3)Al_(5)O_(12),YAG):Ce^(3+),single-doped YAG:Sc^(3+),and double-doped phosphors YAG:Ce^(3+),Sc^(3+) were prepared by spark plasma sintering(SPS)(lower than 1 200℃).The characteristics of synthesized phosphors were determined using scanning electron microscopy(SEM),X-ray diffraction(XRD),and fluorescence spectroscopy.During SPS,the lattice structure of YAG was maintained by the added Ce^(3+) and Sc^(3+).The emission wavelength of YAG:Ce^(3+) prepared from SPS(425-700 nm) was wider compared to that of YAG:Ce^(3+) prepared from high-temperature solid-state reaction(HSSR)(500-700 nm).The incorporation of low-dose Sc^(3+) in YAG:Ce^(3+) moved the emission peak towards the short wavelength.
基金supported by the National Natu-ral Science Foundation of China(Nos.51790494,52271234,and U23A20566)the State Key Laboratory of New Ceramics and Fine Processing Tsinghua University(No.KF202206).
文摘Photoluminescent materials,serving as optical probes,constitute a significant medium for reliable re-mote sensing of fundamental state parameters such as temperature and pressure.Herein,we report a novel Mn^(4+)-activated perovskite-type La_(3) Mg2 SbO9 phosphor(LMS:Mn^(4+))for bifunctional application in both thermometry and manometry.Upon excitation with 341 nm,LMS:Mn^(4+)(0.7%Mn^(4+))emits a bright narrow-band red light peaking at 705 nm with an FWHM(full width at half maximum)of 32 nm.As a thermometer,when the temperature surpasses 298 K,non-radiative transitions from the ^(2)Eg excited state lead to a sharp decrease in decay lifetimes with increasing temperature.This allows for lifetime-based luminescence thermometry with a relative sensitivity of 2.52%K^(−1) at 391 K.Moreover,LMS:Mn^(4+)was processed into a temperature-sensing coating and its non-contact thermometry functionality was validated.In manometry applications,the LMS:Mn^(4+)probe experiences substantial pressure-dependent redshift with a sensitivity of 1.20 nm GPa^(−1) in the testing range of 9.48 GPa,which is about 3.3 times that of conventional ruby probes.Furthermore,its FWHM consistently remains below 37 nm,which con-tributes to a high reliability of pressure measurements.The above results indicate that the LMS:Mn^(4+)constitutes a promising bifunctional luminescence probe material in thermometry and manometry.
基金This work was financially supported by the Department of Science and Technology of Sichuan Province(No.2020YJ0157).
文摘A red-emitting phosphor Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) with partial Al^(3+)/P^(5+) substitution on Si^(4+) was synthesized via a simple solid-state method,and the effects of the introduction of the M^(3+/5+)(M=Al,P)ions on the crystal structure and photoluminescence performance of Ca_(2.91)Si_(2−x)M_(x)O_(7):0.09Eu^(3+) phosphors were investigated.The X-ray diffraction(XRD),energy-dispersive X-ray spectroscopy(EDS),and X-ray photoelectron spectroscopy(XPS)results revealed that the structure of Ca_(3)Si_(2)O_(7) remained the same after the introduction of Al^(3+) and P^(5+) ions.The characteristic emission of Eu^(3+)-doped Ca_(3)Si_(2−x)M_(x)O_(7) phosphors exhibited two main peaks at 617 nm(red)and 593 nm(orange)under excitation at 394 nm,which originated from the^(5)D_(0)→^(7)F_(2)and^(5)D_(0)→^(7)F_(1) electron transitions of Eu^(3+) ions.After the partial substitution of Al^(3+) and P^(5+),the red emission intensities of the Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) phosphors were significantly enhanced by 1.88-and 1.42-fold,respectively,which is attributed to the crystal-field effect around Eu^(3+).Meanwhile,the luminescence intensities of the Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+) and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) phosphors at 210℃ were 79.36%and 77.53%of those at 30°C,respectively,indicating their excellent thermal stability.Moreover,the as-prepared Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+)and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) red-emitting phosphors were combined with a near-ultraviolet chip of 395 nm to fabricate red-light-emitting diode(LED)and white(w)-LED devices with excellent chromaticity features.In summary,Al^(3+)/P^(5+)-substituted Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) can serve as red-emitting phosphors for applications in w-LEDs.
基金supported by the National Natural Science Foundation of China (No.92161121)。
文摘The blue-light-excitable phosphors play a crucial role in the high-performance white LEDs. Here, we report on two new Cu(Ⅰ) coordination network materials as yellow-emitting phosphors prepared by suitably expanded π-conjugated triazole ligands. Upon blue-light irradiation, these complexes exhibit efficient solid-state emission and enhanced photostability. Through incorporating the yellow phosphor and a commercial blue-green powder(BaSi_(2)N_(2)O_(2):Eu^(2+)) with a blue LED chip, the phosphor-converted LED devices display remarkable white emission properties. The experimental results demonstrate that the Cu(Ⅰ)coordination network materials function as promising blue-light excitable phosphors with great application potential for full-spectrum white LEDs.
基金financially supported by the National Natural Science Foundation of China(Grant No.51972130)the Startup Fund of Huazhong University of Science and Technologythe Director Fund of Wuhan National Laboratory for Optoelectronics
文摘Zero-dimensional(0D)hybrid metal halides,which consist of organic cations and isolated inorganic metal halide anions,have emerged as phosphors with efficient broadband emissions.However,these materials generally have too wide bandgaps and thus cannot be excited by blue light,which hinders their applications for efficient white light-emitting diodes(WLEDs).The key to achieving a blue-light-excitable 0D hybrid metal halide phosphor is to reduce the fundamental bandgap by rational chemical design.In this work,we report two designed hybrid copper(I)iodides,(Ph_(3)MeP)_(2)Cu_(4)I_(6)and(Cy_(3)MeP)_(2)Cu_(4)I_(6),as blue-light-excitable yellow phosphors with ultrabroadband emission.In these compounds,the[Cu_(4)I_(6)]^(2-)anion forms an I6 octahedron centered on a cationic Cu_(4)tetrahedron.The strong cation-cation bonding within the unique cationic Cu_(4)tetrahedra enables significantly lowered conduction band minimums and thus narrowed bandgaps,as compared to other reported hybrid copper(I)iodides.The ultrabroadband emission is attributed to the coexistence of free and self-trapped excitons.The WLED using the[Cu_(4)I_(6)]^(2-)anion-based single phosphor shows warm white light emission,with a high luminous efficiency of 65 Im W^(-1)and a high color rendering index of 88.This work provides strategies to design narrow-bandgap 0D hybrid metal halides and presents two first examples of blue-light-excitable 0D hybrid metal halide phosphors for efficient WLEDs.
基金supported by the National Natural Science Foundation of China(Nos.52072101,51972088,52172205)the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.GK229909299001-003)the Postgraduate Research Innovation Fund of Hangzhou Dianzi University(No.CXJJ2022032)。
文摘Optical thermometry as an important local temperature-sensing technique,has received increasing attention in scientific and industrial areas.However,it is still a big challenge to develop luminescent materials with self-activated dual-wavelength emissions toward high-sensitivity optical thermometers.Herein,a novel ratiometric thermometric strategy of Bi^(3+)-activated dual-wavelength emission band was realized in the same lattice position with two local electronic states of La_(3)Sb_(1-x)Ta_xO_(7):Bi^(3+)(0≤x≤1.0)materials based on the different temperature-dependent emission behaviors,benefiting from the highlysensitive and regulable emission to the coordination environment of Bi^(3+).The structural and spectral results demonstrate that the emission tremendously shifted from green to blue with 68 nm and the intensity was enhanced 2.6 times.Especially,the visual dual-wavelength emitting from two emission centers was presented by increasing the Ta^(5+)substitution concentration to 20%or 25%,mainly originating from the two local electronic states around the Bi^(3+)emission center.Significantly,the dual-wavelength with different thermal-quenching performance provided high-temperature sensitivity and good discrimination signals for optical thermometry in the range between 303 and 493 K.The maximum relative sensitivity reached 2.64%/K(La_(3)Sb_(0.8)Ta_(0.2)O_(7):0.04Bi^(3+)@383 K)and 1.91%/K(La_(3)Sb_(0.75)Ta_(0.25)O_(7):0.04Bi^(3+)@388 K).This work reveals a rational design strategy of different local electronic states around the singledoping multiple emission centers towards practical applications,such as luminescence thermometry and white LED lighting.
