Photophysical Properties of Lanthanide (Eu3+, Tb3+) Hybrid Soft Gels of Double Functional Linker of Ionic Liquid–Modified Silane

Four kinds of luminescent hybrid soft gels have been assembled by introducing the lanthanide (Eu³⁺, Tb³⁺) tetrakis β‐diketonate into the covalently bonded imidazolium‐based silica through electrostatic interactions. Here, the imidazolium‐based silica matrices are prepared from imidazolium‐derived organotriethoxysilanes by the sol–gel process, in which the imidazolium cations are strongly anchored within the silica matrices while anions can still be exchanged following application for functionalization of lanthanide complexes. The photoluminescence measurements indicated that these hybrid soft gels exhibit characteristic red and green luminescence originating from the corresponding ternary lanthanide ions (Eu³⁺, Tb³⁺). Further investigation of photophysical properties reveals that these soft gels have inherited the outstanding luminescent properties from the lanthanide tetrakis β‐diketonate complexes such as strong luminescence intensities, long lifetimes and high luminescence quantum efficiencies.     

Development of a ratiometric time-resolved luminescence sensor for pH based on lanthanide complexes

Time-resolved luminescence bioassay technique using lanthanide complexes as luminescent probes/sensors has shown great utilities in clinical diagnostics and biotechnology discoveries. In this work, a novel terpyridine polyacid derivative that can form highly stable complexes with lanthanide ions in aqueous media, (4′-hydroxy-2,2′:6′,2′′-terpyridine-6,6′′-diyl) bis(methylenenitrilo) tetrakis(acetic acid) (HTTA), was designed and synthesized for developing time-resolved luminescence pH sensors based on its Eu³⁺ and Tb³⁺ complexes. The luminescence characterization results reveal that the luminescence intensity of HTTA–Eu³⁺ is strongly dependent on the pH values in weakly acidic to neutral media (pK_a = 5.8, pH 4.8–7.5), while that of HTTA–Tb³⁺ is pH-independent. This unique luminescence response allows the mixture of HTTA–Eu³⁺ and HTTA–Tb³⁺ (the HTTA–Eu³⁺/Tb³⁺ mixture) to be used as a ratiometric luminescence sensor for the time-resolved luminescence detection of pH with the intensity ratio of its Tb³⁺ emission at 540 nm to its Eu³⁺ emission at 610 nm, I_540 nm/I_610 nm, as a signal. Moreover, the UV absorption spectrum changes of the HTTA–Eu³⁺/Tb³⁺ mixture at different pHs (pH 4.0–7.0) also display a ratiometric response to the pH changes with the ratio of absorbance at 290 nm to that at 325 nm, A_290 nm/A_325 nm, as a signal. This feature enables the HTTA–Eu³⁺/Tb³⁺ mixture to have an additional function for the pH detection with the absorption spectrometry technique. For loading the complexes into the living cells, the acetoxymethyl ester of HTTA was synthesized and used for loading HTTA–Eu³⁺ and HTTA–Tb³⁺ into the cultured HeLa cells. The luminescence imaging results demonstrated the practical utility of the new sensor for the time-resolved luminescence cell imaging application.     

Three Lanthanide Metal‐Organic Frameworks Based on an Ether‐Decorated Polycarboxylic Acid Linker: Luminescence Modulation,CO2 Capture and Conversion Properties

Three new isostructural 3D lanthanide metal–organic frameworks (Ln‐MOFs), {H[LnL(H₂O)]?2 H₂O}_n ( 1‐Ln ) (Ln=Eu³⁺, Gd³⁺ and Tb³⁺), based on infinite lanthanide‐carboxylate chains were constructed by employing an ether‐separated 5,5′‐oxydiisophthalic acid (H₄L) ligand under solvothermal reaction. 1‐Eu and 1‐Tb exhibit strong red and green emission, respectively, through the antenna effect, as demonstrated through a combination of calculation and experimental results. Moreover, a series of dichromatic doped 1‐Eu_xTb_y MOFs were fabricated by introducing different concentrations of Eu³⁺ and Tb³⁺ ions, and they display an unusual variation of luminescent colors from green, yellow, orange to red. 1‐Eu with channels decorated by ether O atoms and the open metal sites displays good performance for CO₂ capture and conversion between CO₂ and epoxides into cyclic carbonates.     

Novel bifunctional lanthanide‐centered nanophosphors for latent fingerprint detection and anti‐counterfeiting applications

Production of hybrid organic/inorganic complexes such as lanthanide phosphors in the nanodomain for human fingerprint visualization and anti‐counterfeiting ink under biocompatible UVA and blue light has not yet been studied that thoroughly. This paper presents the preparation of novel, bifunctional, green and red nanophosphors based on Eu³⁺ and Tb³⁺ complexes with quinolinone ligand (H₂L). They have been prepared and characterized for latent fingerprint detection and anti‐counterfeiting ink applications. The analytical data confirm that the ligand acts in a monoanionic bidentate manner through OO donor sites, forming mononuclear complexes, formulated as [Ln(HL)₃(C₂H₅OH)₃] (Ln = Eu³⁺ or Tb³⁺; L = 1‐ethyl‐4‐hydroxy‐3‐(nitroacetyl)quinolin‐2‐(1H)‐one). The Eu³⁺ and Tb³⁺ complexes have nanospherical morphologies with average particle sizes of 17 and 5 nm, respectively. Pure red and green photoluminescence with long lifetime values has been obtained from the Eu³⁺ and Tb³⁺ complexes, respectively, under non‐harmful UVA and blue illumination. Latent fingerprint details, including their characteristic three levels, have been clearly identified from various forensic (non‐porous, semi‐porous, highly fluorescent porous) substrates using red (Eu³⁺) and green (Tb³⁺) nanophosphors. The green nanophosphor powder has a greater capability for visualizing latent fingerprints from highly fluorescent porous surfaces as compared to the red one. Both nanophosphor complexes have been used to develop luminescent ink for anti‐counterfeiting applications.     

A Series of Carboxylic‐Functionalized Ionic Liquids and their Solubility for Lanthanide Oxides

Herein we report the synthesis of propanoic acid functionalized ionic liquids (ILs) with various lengths of alkyl chain on the imidazole ring. The synthesized propanoic acid functionalized ILs were used to dissolve Eu₂O₃ (or Tb₄O₇) due to the formation of europium(III) (or terbium(III)) carboxylate, aimed to get soft luminescent materials combining the properties of ILs and attractive luminescent properties of lanthanide ions. The luminescent behavior of Eu³⁺ and Tb³⁺ in the ILs were investigated by luminescence spectroscopy. The affect of the alkyl chain on the luminescent behavior (the asymmetry parameter (R), the lifetime of ⁵D₀, and the ⁵D₀ quantum efficiency) of Eu³⁺ has been discussed.     

Photophysical Properties of Sol–gel derived Luminescent Silicone Hybrids Synthesized via Facile Amino‐Ene Reaction

Novel luminescent silicone hybrids (LSHs) containing lanthanide ions were prepared via different sol–gel processes. The precursor, dimethyl ester‐functionalized silane, was synthesized via a facile amino‐ene reaction. The coordinated assembly of the ester ligands and lanthanide ions (Eu³⁺, Tb³⁺ and Dy³⁺) occurred. The ester ligands were immobilized onto the Si‐O network backbone during the preparation of the silicone hybrid materials. The particle size can be controlled to ca 50 nm by adjusting the solvent ratio. The obtained materials were characterized by Fourier transform infrared, ¹H nuclear magnetic resonance spectroscopy (NMR), ¹³C NMR, ²⁸Si NMR, X‐ray diffraction, X‐ray photoelectron spectroscopy, thermogravimetric analysis, high‐resolution scanning electronic microscopy and luminescent (excitation and emission) spectroscopy. The coordination state and photophysical performance of the compounds were studied in detail. The terbium‐ and europium‐containing materials show sharp green and red emissions, respectively, which indicate that efficient intramolecular energy transfer took place in these LSHs.     

Encapsulation of LnIII Ions/Dyes within a Microporous Anionic MOF by Post‐synthetic Ionic Exchange Serving as a LnIII Ion Probe and Two‐Color Luminescent Sensors

A new anionic framework {[Me₂NH₂]_0.125[In_0.125(H₂L)_0.25] ? xDMF}_n ( 1 ) with one‐dimensional (1D) channels along the c axis of about 13.06×13.06 Ų, was solvothermally synthesized and well characterized. Post‐synthetic cation exchange of 1 with Eu³⁺, Tb³⁺, Dy³⁺, Sm³⁺ afforded lanthanide(III)‐loaded materials, Ln³⁺@ 1 , with different luminescent behavior, indicating that compound 1 could be used as a potential luminescent probe toward different lanthanide(III) ions. Additionally, compound 1 exhibits selective adsorption ability toward cationic dyes. Moreover, the RhB@ 1 realized the probing of different organic solvent molecules by tuning the energy transfer efficiency between two different emissions, especially for sensing DMF. This work highlights the practical application of luminescent guest@MOFs as sensors, and it paves the way toward other one/multi‐color luminescent host–guest systems by rational selection of MOF hosts and guest chromophores with suitable emissive colors and energy levels.     

Efficient Luminescence from Fluorene‐ and Spirobifluorene‐Based Lanthanide Complexes upon Near‐Visible Irradiation

We describe herein the synthesis and photophysical characterization of new lanthanide complexes that consist of a (9,9‐dimethylfluoren‐2‐yl)‐2‐oxoethyl or a (9,9′‐spirobifluoren‐2‐yl)‐2‐oxoethyl unit as the antenna, covalently linked to a 1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid (DO3A) unit as the Ln³⁺ (Gd³⁺, Eu³⁺, Sm³⁺, Tb³⁺, Dy³⁺) coordination site. We were able to translate the spectroscopic properties of the innovative bipartite ligands into the formation of highly luminescent europium complexes that exhibit efficient emission (?_se>0.1) upon sensitization in the near‐visible region, that is, with an excitation wavelength above 350 nm. The luminescence of the Eu³⁺complexes is clearly detectable at concentrations as low as 10 pM . Furthermore, the structural organization of these bipartite ligands makes the complexes highly soluble in aqueous solutions and chemically stable over time.     

Tunable white-light emission of lanthanide(III) hybrid material based on hectorite

Lanthanide(III) luminescent hybrid materials based on the layered hectorite have been successfully prepared, showing tunable emission colors as well as white light by varying the molar ratio between Eu³⁺ and Tb³⁺.     

A Lanthanide‐Complex‐Based Ratiometric Luminescent Probe Specific for Peroxynitrite

A lanthanide‐complex‐based ratiometric luminescence probe specific for peroxynitrite (ONOO^?), 4′‐(2,4‐dimethoxyphenyl)‐2,2′:6′,2′′‐terpyridine‐6,6′′‐diyl]bis(methylenenitrilo)tetrakis(acetate)‐Eu³⁺/Tb³⁺ ([Eu³⁺/Tb³⁺(DTTA)]), has been designed and synthesized. Both [Eu³⁺(DTTA)] and [Tb³⁺(DTTA)] are highly water soluble with large stability constants at ≈10²⁰, and strongly luminescent with luminescence quantum yields of 10.0 and 9.9 %, respectively, and long luminescence lifetimes of 1.38 and 0.26 ms, respectively. It was found that the luminescence of [Tb³⁺(DTTA)] could be quenched by ONOO^? rapidly and specifically in aqueous buffers, while that of [Eu³⁺(DTTA)] did not respond to the addition of ONOO^?. Thus, by simply mixing [Eu³⁺(DTTA)] and [Tb³⁺(DTTA)] in an aqueous buffer, a ratiometric luminescence probe specific for time‐gated luminescence detection of ONOO^? was obtained. The performance of [Tb³⁺(DTTA)] and [Eu³⁺/Tb³⁺(DTTA)] as the probes for luminescence imaging detection of ONOO^? in living cells was investigated. The results demonstrated the efficacy and advantages of the new ratiometric luminescence probe for highly sensitive luminescence bioimaging application.     

Tailoring of polychromatic emissions in Tb3+/Eu3+ codoped NaYbF4 nanoparticles via energy transfer strategy for white light-emitting diodes

The polychromatic emission and wide-range color tuning in the luminescent nanoparticles are currently of crucial importance, due to the development of color and white light-emitting diode (LED) devices, based on such lanthanide-doped nanostructured materials. By utilization of precipitation method, Tb³⁺-doped and Tb³⁺/Eu³⁺-codoped NaYbF₄ nanoparticles (i.e. NPs) are synthesized. For Tb³⁺-doped NaYbF₄ NPs excited by 377 nm, green emission originating from Tb³⁺ is observed, where its optimum state is obtained when Tb³⁺ content is 25 mol% and the concentration quenching mechanism is found by electric dipole-dipole interaction. Moreover, due to the existence of energy transfer between Tb³⁺ and Eu³⁺, polychromatic emissions are realized in Tb³⁺/Eu³⁺-codoped NaYbF₄ NPs as Eu³⁺ content increases. Through analyzing emission decay times and emission spectra, it was confirmed that the energy transfer mechanism in the synthesized NPs is governed mainly by electric dipole-dipole interaction. Furthermore, the resultant NPs also own strong resistance to temperature, which is verified by temperature-dependent emission spectra, and the activation energies of Tb³⁺ and Eu³⁺ are 0.206 and 0.207 eV, respectively. In addition, by employing designed NPs as yellow-emitting components, the fabricated white-LED emits brightness warm white light with color coordinate of (0.385, 0.380), high color rendering index of 84.3 and low correlated color temperature of 3903 K. This work does not only offer an available route to develop NPs with polychromatic emissions but also devise promising luminescent materials for improving the performance of the phosphor-converted white-LED.     

Preparation,Characterization and Luminescence Study of Chitosan Membrane and Powder Forms with Eu3 + and Tb3 +

Chitosan membranes with trivalent lanthanide ion Eu^{3 +} were prepared at a ratio of 3:1 w/w (chitosan:lanthanide). There was no membrane formation at a ratio of 1:1 w/w (chitosan: Eu^{3 +} or Tb^{3 +}); in this case a white solid powder was obtained. Both chitosan compounds were characterized by elemental analysis (CHN), thermal analysis (TG/DTG), scanning electron microscopy (SEM) and luminescence spectroscopy. CHN analysis was performed only for chitosan compounds in powder form, suggesting that these compounds have the general formula QUILn.6H₂O, where QUI = Chitosan and Ln = Eu^{3 +} or Tb^{3 +}. The results of TG/DTG curves for chitosan membranes with Eu^{3 +} ion indicate that the introduction of this metal into the chitosan structure causes gradual degradation in residual carbons, showing lower weight loss in the Eu^{3 +} membranes compared to pure chitosan membrane. Analysis of luminescence demonstrated that chitosan membranes with Eu^{3 +} ion exhibit emission in the visible region, showing emission bands from chitosan and Eu^{3 +} moieties. For chitosan with Eu^{3 +} and Tb^{3 +} ions compounds, in powder form, the analysis of luminescence suggested that chitosan is not transferring energy to the lanthanide ion; however, the chemical region where the lanthanide ion is found breaks the selection rules and favors the emission of these ions.     

Self‐Assembly versus Stepwise Synthesis: Heterometal–Organic Frameworks Based on Metalloligands with Tunable Luminescence Properties

A new family of heterometal–organic frameworks has been prepared by two synthesis strategies, in which IFMC‐26 and IFMC‐27 are constructed by self‐assembly and IFMC‐28 is obtained by stepwise synthesis based on the metalloligand (IFMC=Institute of Functional Material Chemistry). IFMC‐26 is a (3,6)‐connected net and IFMC‐27 is a (4,8)‐connected 3D framework. The metalloligands {Ni(H₄L)}(NO₃)₂ are connected by binuclear lanthanide clusters giving rise to a 2D sheet structure in IFMC‐28 . Notably, IFMC‐26‐Eu _x Tb _y and IFMC‐28‐Eu _x Tb _y have been obtained by changing the molar ratios of raw materials. Owing to the porosity of IFMC‐26 , Tb³⁺@IFMC‐26‐Eu and Eu³⁺@IFMC‐26‐Tb are obtained by postencapsulating Tb^III and Eu^III ions into the pores, respectively. Tunable luminescence in metal–organic frameworks is achieved by the two kinds of doping methods. In particular, the quantum yields of heterometal–organic frameworks are apparently enhanced by postencapsulation of Ln^III ions.     

Minocycline‐Based Europium(III) Chelate Complexes: Synthesis,Luminescent Properties,and Labeling to Streptavidin

Two chelate ligands for europium(III) having minocycline (=(4S,4aS,5aR,12aS)‐4,7‐bis(dimethylamino)‐1,4,4a,5,5a,6,11,12a‐octahydro‐3,10,12,12a‐tetrahydroxy‐1,11‐dioxonaphthacene‐2‐carboxamide; 5 ) as a VIS‐light‐absorbing group were synthesized as possible VIS‐light‐excitable stable Eu³⁺ complexes for protein labeling. The 9‐amino derivative 7 of minocycline was treated with H₆TTHA (=triethylenetetraminehexaacetic acid=3,6,9,12‐tetrakis(carboxymethyl)‐3,6,9,12‐tetraazatetradecanedioic acid) or H₅DTPA (=diethylenetriaminepentaacetic acid=N,N‐bis{2‐[bis(carboxymethyl)amino]ethyl}glycine) to link the polycarboxylic acids to minocycline. One of the Eu³⁺ chelates, [Eu³⁺(minocycline‐TTHA)] ( 13 ), is moderately luminescent in H₂O by excitation at 395 nm, whereas [Eu³⁺(minocycline‐DTPA)] ( 9 ) was not luminescent by excitation at the same wavelength. The luminescence and the excitation spectra of [Eu³⁺(minocycline‐TTHA)] ( 13 ) showed that, different from other luminescent Eu^III chelate complexes, the emission at 615 nm is caused via direct excitation of the Eu³⁺ ion, and the chelate ligand is not involved in the excitation of Eu³⁺. However, the ligand seems to act for the prevention of quenching of the Eu³⁺ emission by H₂O. The fact that the excitation spectrum of [Eu³⁺(minocycline‐TTHA)] is almost identical with the absorption spectrum of Eu³⁺ aqua ion supports such an excitation mechanism. The high stability of the complexes of [Eu³⁺(minocycline‐DTPA)] ( 9 ) and [Eu³⁺(minocycline‐TTHA)] ( 13 ) was confirmed by UV‐absorption semi‐quantitative titrations of H₄(minocycline‐DTPA) ( 8 ) and H₅(minocycline‐TTHA) ( 12 ) with Eu³⁺. The titrations suggested also that an 1 : 1 ligand Eu³⁺ complex is formed from 12 , whereas an 1 : 2 complex was formed from 8 minocycline‐DTPA. The H₅(minocycline‐TTHA) ( 12 ) was successfully conjugated to streptavidin (SA) (Scheme 5), and thus the applicability of the corresponding Eu³⁺ complex to label a protein was established.     

A Highly Stable Yttrium Organic Framework as a Host for Optical Thermometry and D2O Detection

The yttrium organic framework (Y_0.89Tb_0.10Eu_0.01)₆(BDC)₇(OH)₄(H₂O)₄ (BDC=benzene-1,4-dicarboxylate) is hydrothermally stable up to at least 513 K and thermally stable in air in excess of 673 K. The relative intensities of luminescence of Tb³⁺ and Eu³⁺ are governed by Tb³⁺-to-Eu³⁺ phonon-assisted energy transfer and Tb³⁺-to-ligand back transfer and are responsible for the differing temperature-dependent luminescence of the two ions. This provides a ratiometric luminescent thermometer in the 288–573 K temperature range, not previously seen for MOF materials, with a high sensitivity, 1.69±0.04 % K⁻¹ at 523 K. In aqueous conditions, loosely bound H₂O can be replaced by D₂O in the same material, which modifies decay lifetimes to yield a quantitative luminescent D₂O sensor with a useful sensitivity for practical application.     

Constructing Interfacial Energy Transfer for Photon Up‐ and Down‐Conversion from Lanthanides in a Core–Shell Nanostructure

We report a new mechanistic strategy for controlling and modifying the photon emission of lanthanides in a core–shell nanostructure by using interfacial energy transfer. By taking advantage of this mechanism with Gd³⁺ as the energy donor, we have realized efficient up‐ and down‐converted emissions from a series of lanthanide emitters (Eu³⁺, Tb³⁺, Dy³⁺, and Sm³⁺) in these core–shell nanoparticles, which do not need a migratory host sublattice. Moreover, we have demonstrated that the Gd³⁺‐mediated interfacial energy transfer, in contrast to energy migration, is the leading process contributing to the photon emission of lanthanide dopants for the NaGdF₄@NaGdF₄ core–shell system. Our finding suggests a new direction for research into better control of energy transfer at the nanometer length scale, which would help to stimulate new concepts for designing and improving photon emission of the lanthanide‐based luminescent materials.     

Tuning Mixed‐Valent Eu2+/Eu3+ in Strontium Formate Frameworks for Multichannel Photoluminescence

Cooperative performance of mixed‐valent Eu²⁺/Eu³⁺ in single‐compound phosphors offers significant advantages in color rendering and luminescence efficiency, but their synthesis is challenging because of Eu²⁺ oxidation. Using the tunable nature of the metal‐ion nodes in metal–organic frameworks (MOFs), we present an in situ reduction and crystallization route for preparing MOFs and doping Eu²⁺/Eu³⁺ with a controlled ratio. These materials exhibit rich photoluminescence, including intrinsic‐ and sensitized‐emissions of Eu²⁺ and Eu³⁺, and long‐lived luminescence from charge transfer. Color rendering can be easily achieved by fine‐tuning the valence states of Eu. A linear relation between temperature and the intensity ratio of Eu²⁺/Eu³⁺ emissions provides outstanding properties for applications as self‐calibrated luminescent thermometers with a wide working temperature range. Further incorporation of Tb³⁺ into the MOFs results in white light, utilizing all Eu²⁺,Tb³⁺, and Eu³⁺ emissions in a single crystalline lattice.     

The Role of Ligand Topology in the Decomplexation of Luminescent Lanthanide Complexes by Dipicolinic Acid

In this study, we present the aqueous solution behavior of two luminescent lanthanide antenna complexes (Eu³⁺? 1 , Dy³⁺? 9 ) with different ligand topologies in the presence of dipicolinic acid (DPA, pyridine‐2,6‐dicarboxylic acid). Macrocyclic (1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid, DO3A, 9 ) and acyclic (1,4,7‐triazaheptane‐1,1,7,7‐tetraacetic acid, DTTA, 1 ) ligands have been selected to form a ratiometric pair in which Dy³⁺? 9 acts as a reference and Eu³⁺? 1 acts as a probe for the recognition of DPA. The pair of luminescent complexes in water reveals the capability to work as a DPA luminescent sensor. The change of emission intensity of Eu³⁺ indicates the occurrence of a new sensitization path for the lanthanide cation through excitation of DPA. NMR evidence implies the presence of free 1 and mass spectrometry shows the formation of emitting [EuDPA₂]^? as a result of a ligand exchange reaction.     

Hydrothermal Syntheses,Crystal Structures,and Luminescent Properties of Three Organic‐Lanthanide Complexes with 3‐Hydroxycinnamic Acid

Three new homodinuclear lanthanide(III) complexes [Ln₂(L)₆(2,2′‐bipy)₂] [Ln = Tb^III ( 1 ), Sm^III ( 2 ), Eu^III ( 3 ); HL = 3‐hydroxycinnamic acid (3‐HCA); 2,2′‐bipy = 2,2′‐bipyridine] were synthesized and characterized by IR spectroscopy, elemental analyses, and X‐ray diffraction techniques. Complexes 1 – 3 crystallize in triclinic system, space group P$\bar{1}$ . In all complexes the lanthanide ions are nine‐coordinate by two nitrogen atoms from the 2,2′‐bipy ligand and seven oxygen atoms from one chelating L ligands and four bridging L ligands, forming distorted tricapped trigonal prismatic arrangements. The lanthanide(III) ions are intramolecularly bridged by eight carboxylate oxygen atoms forming dimeric complexes with Ln ··· Ln distances of 3.92747(15), 3.9664(6), and 3.9415(4) Å for complexes 1 – 3 , respectively. The luminescent properties in the solid state of HL ligand and Eu^III complex are also discussed.     

Energy transfer and heat-treatment effect of photoluminescence in Eu-doped TbPO4 nanowires

We have successfully synthesized Eu³⁺-doped TbPO₄ nanowires, which are orderly organized to form bundle-like structure. A thermal treatment up to 600 °C does not modify the size, shape and structure of as-synthesized sample. Due to the energy overlap between Tb³⁺ and Eu³⁺, an efficient energy transfer occurs from Tb³⁺ to Eu³⁺. The effects of Eu³⁺ concentration and thermal treatment on the luminescent properties of Eu³⁺ are investigated. The increase of Eu³⁺ concentration leads to the increase of the energy transfer efficiency from Tb³⁺ to Eu³⁺, but also enhances the probability of the interaction between neighboring Eu³⁺, which results in the concentration quenching. With the heat-treatment, the luminescence of Eu³⁺ presents an obvious increase, but almost no change for the luminescence of Tb³⁺. This difference is explained based on the TGA, DTA, and fluorescent decay dynamics analyses.