Synthesis and characterization of NaYF_4:Yb~(3+),Er~(3+)@silica-N=folic acid nanocomplex for bioimaginable detecting MCF-7 breast cancer cells

Upconversion nanophosphors are new promising nanomaterials to be used as biolabels for detection and imaging of cancer cells.These nanophosphors absorb long-wavelength excitation radiation in the infrared or near infrared region and emit shorter wavelength,higher energy radiation from ultraviolet to infrared.In this paper,we studied the hydrothermal method and optical properties of the functionalized NaYF_4:Yb~(3+),Er~(3+)for biomedical application.After synthesis,these NaYF_4:Yb~(3+),Er~(3+)nanophosphors were functionalized with aminosilanes and folic acid.Folic acid binds to the folate receptor on the surface of MCF-7 breast cancer cells and this binding promotes internalization of the nanophosphors via endocytosis.The sizes of the functionalized NaYF_4:Yb~(3+),Er~(3+)@silica-N=FA(folic acid) nanophosphors can be controlled with length of the rod about 300-800 nm and diameter of the rod about 100-200 nm.Phase structure of NaYF_4:Yb~(3+),Er~(3+)is in hexagonal crystal system.The photo luminescence(PL) spectra of the functionalized NaYF_4:Yb~(3+),Er~(3+)@silica-N=FA nanophosphors were measured.These nanophosphors emit in red color with the strongest band at 650 nm under 980 nm excitation.This result can provide NaYF_4:Er~(3+),Yb~(3+)@silica-N=FA complex for developing fluorescence label and image tool in cancer biology and medicine.     

Cooperative energy acceptor of three Yb3+ ions

Our previous work first reported the cooperative sensitized luminescence from Cu~(2+) or Pb~(2+) by three clustered Yb~(3+) ions, in which three NIR photons can be converted into a high energy photon. Could a reverse process happen that a high energy photon is cut into three NIR photons? This work demonstrated an example of three-photon quantum cutting(QC) phosphor,CaF_2:Ce~(3+),Yb~(3+), in which three clustered Yb~(3+) ions(Yb~(3+)-trimer) cooperatively and indirectly received a 306 nm ultraviolet(UV) photon energy transferred from a Ce~(3+) ion in 5 d excited state and emitted three 975 nm near-infrared(NIR)photons. The cluster destruction experiments were designed to verify the necessity of the presence of Yb~(3+)-trimers for QC. The dynamical analysis on luminescence of Ce~(3+) ions confirmed the energy transfer from Ce~(3+) ions to Yb~(3+)-trimers. The doping concentration effect on luminescence was investigated.Furthermore, the maximum energy transfer(ET) efficiency and the corresponding QC efficiency were estimated to be 61% and 222%, respectively. Therefore, the reported three-photon QC phosphor has an attractive prospect in efficiently harvesting solar energy for silicon solar cells.     

Temperature sensing behavior of Tm~(3+):~1G_4(a),~1G_4(b) in oxyfluoride glass ceramics containing BaYb_xY_(1-x)F_5 nanocrystals

Tm~(3+)-doped transparent oxyfluoride glass ceramics containing BaYb_xY((1-x))F_5 nanocrystals were prepared via high temperature solid phase melting method,of which up-conversion emission is achieved by the Yb~(3+)-mediated energy transfer process.The required photon number of Tm~(3+)ions emissions in BaYb_xY_((1-x))F_5 nanocrystals was calculated through the luminescence spectra,revealing the strong dependence of energy transfer mechanism on Yb~(3+)ions concentration.Meanwhile,based on the fluore scence intensity ratio technology,the effect of different energy transfer mechanism on the temperature sensitivity was investigated by the temperature-dependent luminescence intensity of thermally coupled energy levels of Tm~(3+):~1G_4(a),~1G_4(b).The obtained sensitivity decreases with the increase of Yb~(3+)ions content,which is mainly attributed to the changes in photon absorption process of Tm~(3+):~1G_4(b).     

Near-infrared luminescent Nd~(3+)/Yb~(3+)-codoped metal-organic framework for ratiometric temperature sensing in physiological range

Self-calibrating luminescent thermometry employing luminescence within the optical transparency windows provides a promising prospect for temperature measurement in the biological fields.In this work,a new Nd~(3+)/Yb~(3+)-codoped metal-organic framework Nd_(0.95)Yb_(0.05)BPTC showing threedimensional anionic network,obtained by reacting ligand [1,1'-biphenyl]-3,3',5,5'-tetracarboxylic acid(H_4BPTC) with Nd~(3+) and Yb~(3+) ions under solvothermal conditions,is reported.Upon 808 nm photoexcitation,Nd_(0.95)Yb_(0.05)BPTC simultaneously emits the characteristic near-infrared luminescence of Nd~(3+) and Yb~(3+) ions based on the efficient energy transfer from Nd~(3+) to Yb~(3+) ions.In addition,the emission intensity ratio of Yb~(3+) and Nd~(3+) shows good exponential-like response to temperature in the physiological range of 293-323 K.The feature properties of Nd_(0.95)Yb_(0.05)BPTC include near-infrared absorption and emission,favorable temperature sensitivity and accurate temperature uncertainty,as well as good chemical stability,making such system useful in biomedical applications.     

Sensitizing effect of Nd~(3+) on Tb~(3+) activated ZrP_2O_7 long persistent phosphor materials

The long persistent phosphors of Zr_(0.97)P_2 O_7:0.018 Tb~(3+),0.012 Nd3+with Nd~(3+)as sensitized ions and Tb~(3+)as emission centers were synthesized using high temperature solid state reaction.The crystal structure and defects,excitation and emission spectra,decay curves and thermoluminescence(TL) curves of the phosphors were investigated.The synthesized Zr_(0.97)P_2 O_7:0.018 Tb3+,0.012 Nd3+is essentially in line with the standard card PDF#49-1079.The emission band with main peak at 548 nm exhibits the characteristic transitions of ~5 D_3-~7 F_j(j=5,4) and ~5 D3-~7 F_j(j=6,5,4,3) of Tb~(3+).The analysis of excitation and emission spectra shows that there exists the overlap between the emission peaks of Nd~(3+)at 466 and 485 nm and the excitation of Tb3+at 443 and 485 nm,and the energy transfer from Nd3+to Tb3+plays an important role in the improvement of luminescence properties.The decay curves shows that Zr_(0.97)P_2 O_7:0.018 Tb3+,0.012 Nd3+has longer afterglow time than ZrP_2 O_7 and Zr_(0.982)P_2 O_7:0.018 Tb3+.Additionally,the TL curves indicate that the trap depth at 0.72 eV in Zr_(0.97)P_2 O_7:0.018 Tb~(3+),0.012 Nd3+is to the benefit of the afterglow time.The possible luminescence mechanism of ZrP_2 O_7:Tb~(3+),Nd3+is proposed on the basis of the XPS spectra,EPR spectra,excitation and emission spectra,decay curves,TL curves and the analysis of defect equations.     

Tunable luminescence and energy transfer in Y_2BaAl_4SiO_(12):Tb~(3+),Eu~(3+)phosphors for solid-state lighting

Single-phase Y₂BaAl₄SiO₁₂:Tb³⁺,Eu³⁺phosphors with adjustable luminescence were successfully prepared by high-temperature solid-state reaction method.The structural,luminescent properties and ene rgy transfer(ET) process of Y₂BaAl₄SiO₁₂:Tb^(³⁺),Eu³⁺phosphors were syste matically analyzed with the help of X-ray diffraction(XRD),scanning electron microscopy(SEM),excitation spectra,emission spectra and photoluminescence decay curves.Tunable luminescence ranging from green through yellow and definitively to red can be achieved by elevating amounts of Eu³⁺ions in Tb³⁺,Eu³⁺co-doped samples.Besides,the ET mechanism and efficiency were also analyzed and the maximum ET efficiency is 67%.All the results show that Y₂BaAl₄SiO₁₂:Tb³⁺,Eu³⁺phosphors can be used in solid-state lighting.     

Effect of RE~(3+) electronegativities on luminescence property of Ba_5Si_8O_(21):Eu~(2+) persistent phosphor

A series of Ba_5Si_8O_(21):0.02Eu~(2+),0.09RE~(3+) persistent phosphors were synthesized by the solid-state reaction method.The measurement results of photoluminescence(PL),phosphorescence and thermoluminescence(TL)were analysed and discussed.The XRD results showed that samples codoped with different RE~(3+) were Ba_5Si_8O_(21) single pure phase.Under the excitation,all samples exhibited a broad Eu~(2+) characteristic emission,and the La~(3+) co-doped sample emitted the brightest photoluminescence even though its persistent luminescence property was the worst because of the weakest electronegativity.However,Nd~(3+) electronegativity was suitable,thus after activation,the Ba_5Si_8O_(21):Eu~(2+),Nd~(3+) sample had the best persistent luminescence performance with the highest phosphorescence intensity and the persistent luminescence decay time beyond 8 h.The Nd~(3+) co-doped sample also had the largest thermoluminescence integral area which proved effectively it had longer persistent luminescence time.The luminescence mechanism was also proposed to study the photoluminescence and persistent luminescence process.These results showed that RE~(3+) electronegativities were distinctly important for persistent phosphors and choosing suitable electronegativity codopant was conducive to enhancing the phosphorescent performance.     

Energy transfer in co-and tri-doped Y_3Al_5O_(12) phosphors

Single-doped(Ce~(3+),Tb~(3+)), co-doped(Ce~(3+)-Tb~(3+), Ce~(3+)-Yb~(3+), Tb~(3+)-Yb~(3+)) and tri-doped(Ce~(3+)-Tb~(3+)-Yb~(3+)) Y_3Al_5O_(12) phosphors were synthesized by a solid-state reaction method. The XRD, excitation and emission spectra and the fluorescence lifetime of the samples were measured. The energy transfer mechanism was also investigated. The results showed that the energy transfer efficiency from Tb~(3+) to Ce~(3+) was 51% and the energy transfer efficiency from Ce~(3+) to Yb~(3+) was 63.1%. Concomitantly, both were more efficient than that from Ce~(3+) to Tb~(3+)(7%) and from Tb~(3+) to Yb~(3+)(10.2%). Also, the Yb~(3+) ions received energy mainly from Ce~(3+) ions in Ce~(3+)-Tb~(3+)-Yb~(3+) tri-doped Y_3Al_5O_(12) phosphors. Among these materials, Ce~(3+)-Yb~(3+) co-doped YAG phosphors are a better choice than others as a down-conversion material due to their higher energy transfer efficiency.     

Spectroscopic properties and energy transfer of Nd3+/Ho3+-doped Ga2O3-GeO2 glass by codoping Yb3+ ion

This study presented the luminescence properties of Nd³⁺/Yb³⁺/Ho³⁺ dopant ions inside a host based on Ga₂O₃-GeO₂-Li₂O（GGL） glass. The measured differential scanning calorimetry result showed that GGL glass exhibited excellent stability against devitrification with ?T=135 oC. Obvious 543 and 657 nm emissions were observed in Nd³⁺/Ho³⁺-codoped sample. The incorporation of Yb³⁺ into Nd³⁺/Ho³⁺-codoped glass system had resulted in enhanced upconversion emission intensity under the excitation of 808 nm and/or 980 nm laser diode（LD）. The possible mechanisms and related discussions on this phenomenon were presented. It was noted that the presence of Yb³⁺ yielded an enhancement about 7 and 11 times in the 543 and 657 nm emission intensities respectively under 808 nm excitation due to the energy transfer from Nd³⁺ to Ho³⁺ via Yb³⁺ ion. Here Yb³⁺ played a major role as a bridging ion. While enhanced 543 and 657 nm emission intensities under the excitation of 980 nm LD originated from the sensitization effect of Yb³⁺. Our results showed that Nd³⁺/Ho³⁺/Yb³⁺ triply doped GGL glass might be a promising candidate for the development of visible-laser materials.     

A single-phased white-emitting Ca_2Ga_2GeO_7:Dy~(3+) phosphor with different charge compensation ions

A novel white-emitting Ca_2Ga_2GeO_7:Dy~(3+) phosphor was synthesized via a high-temperature solid-state reaction.The crystal phase was analyzed by X-ray diffraction(XRD),and the photoluminescence(PL) properties were studied by luminescence spectra and fluorescence decay curves.Under the excitation of 347 nm,the obtained phosphor exhibited strong emission in the blue region peaked at 478 nm,yellow at 574 nm and a weak red emission band at 665 nm,corresponding to the characteristic transitions of ~4F_(9/2)to ~6H_(15/2),~6H_(13/2) and ~6H_(11/2) of Dy~(3+),respectively.By varying the doping concentration of Dy~(3+),tunable colors from blue-white to yellow-white were obtained in the phosphors.Besides,by codoping charge compensators(Li~+,Na~+,K~+ and Ga~(3+)) in Ca_2Ga_2GeO_7:Dy~(3+),the optimum CE color coordinate and PL intensity were obtained in Ca_2Ga_2GeO_7:Dy~(3+),K~+.Accordingly,the PL mechanism of Ca_2Ga_2GeO_7:Dy~(3+) was discussed briefly.     

Luminescence of halophosphate solid-solution Ca5(PO4)3(F0.8Cl0.2):Eu2+,Mn2+ for WLED

Solid-solution based luminescent materials have been widely explored due to their tunable optical properties in recent years. In this work, instead of more common cation-substitution approach, we investigated the luminescence properties of Eu~(2+) and Mn~(2+) co-doped halophosphate solid solution Ca_5(PO_4)_3(F_(0.8)Cl_(0.2)) via anion substitution synthesized by high temperature solid state reaction method.The formation of the solid solution was confirmed by X-ray diffraction(XRD) characterization, which indicates that the introduction of certain proportion of Cl~-will not make significant change on the Ca_5(PO_4)_3F lattice. We also studied the energy transfer from Eu~(2+) to Mn~(2+) in the host so as to obtain white light emission via adjusting the doping concentrations of Eu~(2+) and Mn~(2+). The white light emission was achieved through combination of Eu~(2+) blue emission and Mn~(2+) red-orange emission with appropriate proportions. The results suggest that Ca_5(PO_4)_3(F_(0.8)Cl_(0.2)):0.01Eu~(2+),0.18 Mn~(2+) could be a potential WLED phosphor working under ultraviolet excitation.     

Hydrothermal synthesis of uniform CdWO_4:Eu~(3+) microrods as single component for UV-based WLEDs

A series of single-composition emission-tunable CdWO_4:Eu~(3+) uniform size nanorods were synthesized by polyvinylpyrrolidone(PVP) assisted hydrothermal process. The products were measured by powder X-ray diffraction(PXRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), photoluminescence, and fluorescent decay test. The results showed that reaction time, temperature, p H values and Eu~(3+) doped concentration played important roles in determining the morphologies and photoluminescent properties. And we also investigated its use in Ga N LED, warm-white-light could be obtained by the combination of the bright blue light originated from the charge transfer transition in the tungstate groups and the near UV light from LED chip with the red emission from 4f-4f transition of Eu~(3+), respectively. By properly tuning the doping concentration of Eu~(3+), chromaticity coordinates(0.30 0.22) could be achieved under the 380 nm excitation and its color rendering index was 80.6. So it has potential application in warm-WLED and replacing the commercial YAG:Ce phosphor which absence of red band emission.     

Significant enhancement of blue photoluminescence intensity of Dy~(3+) modified Sr_6Ca_4(PO_4)_6F_2:Eu~(2+) phosphors

Blue-emitting phosphors Sr_6 Ca_4(PO_4)_6 F_2:Eu~(2+)(SCPF:Eu~(2+)),Sr_6 Ca_4(PO_4)_6 F_2:Eu~(2+),Dy~(3+)(SCPF:Eu~(2+),Dy~(3+))and Sr_6 Ca_4(PO_4)_6 F_2:Eu~(2+),Dy~(3+),Si~(4+)(SCPF:Eu~(2+),Dy~(3+),Si~(4+)) with apatite structure were successfully synthesized by traditional solid-state reaction under reducing atmosphere.Eu~(2+),Dy~(3+) and Si4+ions occupy the corresponding sites of Sr~(2+),Ca~(2+) and P~(5+).Strong broad blue photo luminescence band is exhibited in SCPF:Eu~(2+),Dy~(3+) phosphor ranging from 400 to 550 nm centered at 455 nm and Dy~(3+) ions are vital in creating traps.Emission intensity of Eu~(2+),Dy~(3+) co-doped SCPF:0.02 Eu~(2+),0.02 Dy~(3+) is about 1.8 times that of SCPF:0.02 Eu~(2+) and electron trap centers serve as energy transporting media.To further elucidate the formation and effect of the specific defect on the luminescence of SCPF:0.02 Eu~(2+),0.02 Dy~(3+) phosphor,the thermoluminescence properties,decay curves and thermal stability studies were performed while the Si~(4+)-P~(5+) charge compensated pho sphor SCPF:0.02 Eu~(2+),0.02 Dy~(3+),0.02 Si~(4+) was prepared as a contrast.All the results of present work indicate that Dy~(3+) co-doping can obviously enhance photoluminescence intensity of SCPF:0.02 Eu~(2+) by the electron traps generated by non-equivalence replacement of Dy~(3+)-Ca~(2+).     

Synthesis,optical properties,and energy transfer of Ce~(3+),Tb~(3+) doped KLu_2F_7

Ce~(3+), Tb~(3+) doped orthorhombic phases of KLu_2F_7 microcrystals with hexagonal disk morphology were synthesized by a hydrothermal method. Enhanced emissions of Tb~(3+) were observed in the Ce~(3+)/Tb~(3+) co-doped KLu_2F_7 sample compared to the Tb~(3+) single-doped KLu_2F_7. The energy transfer efficiency from Ce~(3+) to Tb~(3+) was calculated by the photoluminescence intensity in the Ce~(3+)/Tb~(3+) co-doped KLu_2F_7 samples. The average separations between Ce~(3+) and Tb~(3+) were calculated and the critical distance was 0.922 nm estimated by method of concentration quenching. The theoretical calculation proved the results. The theoretical analysis also suggested that the energy transfer from Ce~(3+) to Tb~(3+) in the KLu_2F_7 occurred predominantly via the dipole-quadrupole interaction. The KLu_2F_7 should be good host materials for emitters.     

Recent progress of energy transfer and luminescence intensity boosting mechanism in Nd~(3+)-sensitized upconversion nanoparticles

Rare earth doped upconversion nanoparticles can be considered as the spice of research in the field of luminescence nanomaterials due to their unique optical properties such as near-infrared excitation.Enormous works have been reported about biomedical applications of 980 nm excited and Yb~(3+)-sensitized upconversion nanoparticles.However,980 nm excitation wavelength overlaps with the absorption band of water molecules in the biological environment,leading to overheating effect that can induce thermal damages of normal cells and tissues.Recently,Nd~(3+)-sensitized upconversion nanoparticles which can be excited with 808 nm has been widely investigated as alternative nanoparticles that can surmount this issue of overheating effect.Even though Nd~(3+)-sensitized upconversion nanoparticles can reduce the overheating effect by 20 fold as compared to Yb~(3+)-sensitized counterpart,there are several factors that reduce the upconversion luminescence intensity.In this review article,photon energy harvesting and transferring mechanisms in Nd~(3+),Yb~(3+)and emitter ions co-doped upconversion nanoparticles under 808 nm excitation are briefly discussed.Factors that affect upconversion luminescence intensity and quantum yield of Nd~(3+)-sensitized upconversion nanoparticles are also addressed.Besides,some of the important strategies that have been recently utilized to boost upconversion luminescence intensity of Nd~(3+)sensitized upco nversion nanoparticles are tho roughly summarized.Lastly,the future challenges in the area and our perspectives are in sight.     

Synergistic effect of crystal structure and concentration quenching on photoluminescence of Er~(3+) doped upconversion nanocrystals

YbF_(2.357), YbF_3, Ba_2 YbF_7, and Ba _2 upconversion nanocrystals doped with emitter Er~(3+) ion were synthesized in the same solvent system just with changing the molar ratio of Ba~(2+) to Yb~(3+) in the precursor, which corresponed to the crystal phases of rhombohedral, orthorhombic, tetragonal, and cubic, respectively. All the samples emitted both 660 nm red light and 543/523 nm green light which originated from Er~(3+)-4f~n electronic transitions ~4F_(9/2)-~4I_(15/2) and ~4S_(3/2)/~2H_(11/2)-~4I_(15/2), respectively. It was worth mentioning that YbF 3:Er~(3+), Ba_2 YbF_7:Er~(3+), and BaF_2:Er~(3+) could emit dazzlingly bright light even under the excitation of a 980 nm CW laser with output power of 0.1 W. Upconversion emission mechanism analysis indicated that the intensity ratio of red to green light highly depended on the synergistic effect of crystal structure, concentration quenching, and particle size, but were not sensitive to crystallinity as previously reported for NaL nF_4(Ln=lanthanide).     

Luminescence and energy transfer of color-tunable Lu_2MgAl_4SiO_(12):Eu~(2+),Ce~(3+),Mn~(2+) phosphors

Energy transfer among the co-doped activators is an efficient route to achieve color-tunable emission in inorganic phosphors.Herein,photoluminescence tuning from blue to cyan has been achieved in the Lu_2MgAl_4 SiO_(12);Eu~(2+),Ce~(3+)phosphors by varying the Ce~(3+) concentration with a fixed Eu~(2+)content.With the further introduction of a Mn~(2+)-Si4+couple into the host lattice,the emission color can be tuned to red through the energy transfer of Eu~(2+)and Mn~(2+).The luminescence properties and the energy transfer mechanism were studied in detail.The energy transfer from Eu~(2+)to Ce~(3+)is certified as a dipolequadrupole interaction with the energy transfer efficiency of 41.4% and Eu~(2+)to Mn~(2+)belongs to a dipole-dipole interaction with the energy transfer efficiency of 94.3%.The results imply that this singlephased Lu_2MgAl4 SiO_(12):Eu~(2+),Ce~(3+),Mn~(2+)phosphor has a potential prospect for application in near-UV chip pumped white light emitting diodes.     

Structural characterization and optical properties of long-lasting CaAl_2O_4:Eu~(2+),Nd~(3+) phosphors synthesized by microwave-assisted chemical co-precipitation

The present paper reported the structural and luminescent properties of Eu~(2+) and Nd~(3+) doped CaAl_2O_4 phosphor. The samples were prepared by microwave-assisted chemical co-precipitation(MA-CCP), a synthesis technique which is suitable for small and uniform particle that could be used directly without grinding. The effects of different microwave temperatures on structure and photoluminescence behavior were studied. Formation of a phosphor and phase purity were confirmed by X-ray diffraction technique(XRD) with variable microwave temperatures. XRD analysis showed that the phosphors prepared by MA-CCP method at the temperature of 750, 900oC, respectively and solid-state reaction(SSR) method at 1300oC consisted of impurities. Commission Internationale de L'Eclairage(CIE) color coordinates of CaAl_2O_4:Eu~(2+),Nd~(3+) were suitable as blue light emitting phosphor. Excitation and emission peaks of the samples prepared by different methods in this study were almost the same. The images of SEM showed that the size of the phosphors prepared by MA-CCP method reached a submicrometer.     

Na_2WO_4:Eu~(3+),Tb~(3+)光致发光材料的发光性质和能量传递

利用溶胶-凝胶法,将激活离子Eu~(3+)和Tb~(3+)以单一或混合的形式掺入体系得到了光致发光材料.分别研究了材料中激活离子Eu~(3+)和Tb~(3+)的含量及其离子之间的能量传递关系.主要利用材料的三维荧光光谱,激发光谱和发射光谱对其的发光性质进行了分析;结果发现,材料中有两个发光中心,分别为Eu~(3+)和Tb~(3+),在不同的波长光的激发下得到的材料的红绿色发光强度不同,而且Eu~(3+)和Tb~(3+)的掺杂浓度比对发光色度影响很大.所以可以根据选择最适合的Eu~(3+)和Tb~(3+)的浓度比来控制材料的发光色,也可以通过不同的激发波长对材料的色度进行微调.     

Broadband near-infrared luminescence and energy transfer of Cr~(3+),Ce~(3+) co-doped Ca_2LuHf_2Al_3O_(12) phosphors

Broadband near-infrared phosphors are highly desirable for food testing.Targeted Ca₂LuHf₂Al₃O₁₂:Cr³⁺(CLHA:Cr³⁺) and Ca₂LuHf₂Al₃O₁₂:Ce³⁺,Cr³⁺(CLHA:Ce³⁺,Cr^(³⁺)) phosphors were synthesized by the conventional high-temperature solid state reaction.The CLHA:Cr³⁺phosphor,with a good thermal stability,shows a red shift owing to radiation reabsorption and non-radiative transition with increasing Cr³⁺content.For co-doped sample,the emission intensity of Cr³⁺can be enhanced by three times due to the energy transfer from Ce³⁺to Cr³⁺,which can be evidenced by a significant overlap between the PLE of Cr³⁺single-doped phosphor and the PL of Ce³⁺single-doped phosphor.In addition,the mechanism of energy transfer is identified as a quadrupole-quadrupole interaction according to decay Lifetime and Dexter’s energy transfer formula.The broadband NIR emission peaked at 775 nm of CLHA:Cr³⁺,Ce³⁺phosphor shows a bright prospect in nondestructive quality-control analysis systems for food.