Structural and luminescence properties of silica powders and transparent glass‐ceramics containing LaF3:Eu3+ nanocrystals

In this work, silica powders and transparent glass‐ceramic materials containing LaF₃:Eu³⁺ nanocrystals were synthesized using the low‐temperature sol‐gel technique. Prepared samples were characterized by TG/DSC analysis as well as X‐ray diffraction and IR spectroscopy. The transformation from liquid sols toward bulk powders and xerogels was also examined and analyzed. The optical behavior of prepared Eu³⁺‐doped sol‐gel samples were evaluated based on photoluminescence excitation (PLE: λ_em = 611 nm) and emission (PL: λ_exc = 393 nm, λ_exc = 397 nm) spectra as well as luminescence decay analysis. The series of luminescence lines located within reddish‐orange spectral scope were registered and identified as the intra‐configurational 4f⁶‐4f⁶ transitions originated from Eu³⁺ optically active ions (⁵D₀ → ⁷F_J, J = 0‐4). Moreover, the R/O‐ratio was also calculated to estimate the symmetry in local framework around Eu³⁺ ions. The luminescence spectra and double‐exponential character of decay curves recorded for fabricated nanocrystalline sol‐gel samples (τ₁(⁵D₀) = 2.07 ms, τ₂(⁵D₀) = 8.07 ms and τ₁(⁵D₀) = 0.79 ms, τ₂(⁵D₀) = 9.76 ms for powders and glass‐ceramics, respectively) indicated the successful migration of optically active Eu³⁺ ions from amorphous silica framework to low phonon energy LaF₃ nanocrystal phase.     

Luminescence performance of yttrium-stabilized zirconia ceramics doped with Eu3+ ions fabricated by Spark Plasma Sintering technique

Yttrium stabilized zirconia (YSZ) ceramics doped with Eu³⁺ ions have been successfully fabricated by Spark Plasma Sintering (SPS) technique. The influence of the europium concentration and post-annealing process on the structural, optical, and luminescent properties of the ceramics has been studied. It is shown that an increase in the europium concentration from 0.1 to 3 wt% does not lead to significant changes in the transmission spectra. However, annealing in air atmosphere at temperature from 700 °C to 1300 °C significantly affects the transmission spectrum, as a possible consequenceofthe formation of oxygen vacancy defects. The analysis of the photoexcitation and photoluminescence spectra showed that the main excitation bands are determined by direct excitation of the ⁷F₀ ground state of Eu³⁺ions to the higher 4f energy levels with further radiation transitionsfrom these states. Moreover, the europium ion in the obtained ceramics occupy low-symmetry sites without inversion center.The luminescence decay kineticsare described by a doubleexponential function with decay time τ₁ ~ 20 ns and τ₂~ 90 ns for intrinsic emission centers and millisecond (τ ~ 1.4 ms) for Eu³⁺emission, for all investigated ceramics. The luminescence spectra in nanosecond time region are characteristic for yttrium-stabilized zirconia and are caused by oxygen vacancies in the presence of heavy cations (Y³⁺ and Eu³⁺).     

Luminescent properties of MgAl2O4 ceramics doped with rare earth ions fabricated by spark plasma sintering technique

MgAl₂O₄ ceramics doped with rare earth ions (Eu²⁺ and Ce³⁺ ions) were fabricated by spark plasma sintering technique. A complex characterization of the crystalline and defect structure of the ceramic by XRD was carried out. Absorption, excitation, photo- and cathodoluminescence spectra were studied. The photoluminescence spectrum shifts to the blue region with a maximum at λ_em =?475?nm for the MAS:0.1Ce ceramics. The nature of this luminescence can be caused by the radiative transitions in the cerium ion 5d–4f. The emission spectrum of MAS:0.1Eu has a “green” band emission in range of 400–700?nm centered around 500?nm, which can be ascribed to the allowed 4f⁶5d¹→4f⁷ (5d–4f) transition of Eu²⁺. In the millisecond time range, simultaneously with the emission of the complex host centers, the impurity luminescence bands of the chromium ion are recorded. It was shown that cathodoluminescence spectra in nanosecond time range can be decomposed into several emission bands at 2.72, 3.01, 3.37, 3.63–3.82?eV caused by F-type centers. It was demonstrated that the Eu²⁺ and Ce³⁺ ions lead to change the intensity ratio of the luminescence bands. The luminescence decay kinetics of synthesized spinel ceramics in nano- and millisecond time range were investigated in detail.     

Lead fluoride β-PbF2 nanocrystals containing Eu3+ and Tb3+ ions embedded in sol-gel materials: Thermal,structural and optical investigations

Nanocrystalline β-PbF₂ phase singly-doped with Eu³⁺ and Tb³⁺ ions have been successfully synthesized using sol-gel technique and subsequent heat-treatment of xerogels at 350 °C. Thermal behavior and structural properties of obtained materials were studied using thermogravimetric analysis (TG), differential scanning calorimetry (DSC) as well as FT-IR and Raman techniques. XRD results confirmed formation of β-PbF₂ nanocrystals embedded in silica amorphous hosts after annealing at 350 °C. Moreover, the photoluminescence properties have been investigated based on excitation and emission spectra as well as decay analysis from the ⁵D₀ (Eu³⁺) and the ⁵D₄ (Tb³⁺) excited states. The sharp intraconfigurational 4f⁶−4f⁶ and 4f⁸−4f⁸ emission transitions assigned as the ⁵D₀→⁷F_J (J=0–4) of Eu³⁺ and the ⁵D₄→⁷F_J (J=6-3) of Tb³⁺ bands, respectively, were registered. The most prominent bands in studied xerogels and glass-ceramic materials are related to the following electronic transitions: ⁵D₀→⁷F₁ (orange) and ⁵D₀→⁷F₂ (red) (Eu³⁺) as well as ⁵D₄→⁷F₅ (green) and ⁵D₄→⁷F₆ (blue) (Tb³⁺). Thus, the R/O (Eu³⁺) and G/B (Tb³⁺) luminescence intensity ratios were calculated and analyzed. Luminescence decay kinetic clearly indicated a presence of two different surroundings around Eu³⁺ and Tb³⁺ dopants in β-PbF₂-based glass-ceramic samples. In such singly-doped with Eu³⁺ and Tb³⁺ materials, the longer luminescence lifetimes (Eu³⁺: τ₁(⁵D₀)=0.90 ms, τ₂(⁵D₀)=5.15 ms; Tb³⁺: τ₁(⁵D₄)=0.48 ms, τ₂(⁵D₄)=4.01 ms) of an appropriate excited states were achieved in comparison to xerogel hosts (Eu³⁺: τ(⁵D₀)=0.38 ms; Tb³⁺: τ(⁵D₄)=0.49 ms). The obtained results indicate the incorporation of Eu³⁺ and Tb³⁺ ions into nanocrystalline phase during ceramization process.     

Controllable synthesis of glass ceramics containing YF3:Eu3+ nanocrystals: Well-preserved Eu and prolonged lifetime

Monolithic luminescent glass-ceramic (GC) embedded with fluoride-based nanocrystals (NCs) has drawn much attention as it is stable and possesses long fluorescent lifetime, while only small partial of optically active ions could enter the fluoride NCs prepared by conventional crystallization process. In this work, YF₃:Eu³⁺ embedded GCs have been controllably synthesized by Spark Plasma Sintering at a relatively low sintering temperature (960°C) within 10 minutes. The GC samples show typical sharp reddish-orange emissions peaking at λ = 590 nm and 620 nm, which can be ascribed to the ⁵D₀ → ⁷F_j transitions of Eu³⁺ located in the tetrahedral coordination sites of the YF₃ NCs. Significantly, a small R/O ratio (photoluminescence intensity ratio of ⁵D₀ → ⁷F₂/⁵D₀ → ⁷F₁) suggests that majority of Eu³⁺ ions are well preserved in YF₃ NCs, which is confirmed by the EDS and TEM results that highly crystallized YF₃:Eu³⁺ NCs are homogeneously dispersed into the silica glass matrix without interfacial reaction. Hence, the lifetime of GC sample is prolonged to 6.8 ms These results demonstrate that Eu³⁺ could be well protected and resided in YF₃ low phonon crystal by this method to fabricate GC composites with high optical performance.     

Photoluminescence and optical properties of Eu3+/Eu2+-doped transparent Al2O3 ceramics

Transparent Eu³⁺-doped (0.05–0.15 at. %) alumina ceramics with fine-grained microstructure were prepared and studied in terms of optical properties and photoluminescence (PL). The light transmission through ceramics up to dopant concentrations 0.125 at. % is dominated by birefringence scattering at grain boundaries. As confirmed by HRTEM/EDS element mapping, high photoluminescence intensity was achieved as the result of the dopant segregation at grain boundaries. The PL emission spectra of Al₂O₃:Eu³⁺ ceramics exhibited red light emissions with the highest intensity (394 nm excitation) for material containing 0.125 at. % of Eu³⁺. The luminescence decay was single-exponential with a lifetime ～1.5 ms. The post-sintering reduction of Eu³⁺→Eu²⁺ under an H₂ atmosphere (at 1300 °C) was difficult. Two simultaneously coexisting Eu²⁺ emitting PL centers were identified, one emitting blue light with average decay constant of 150 ns, and the other green light (more intense) with average decay constant of 1.3 μs.     

Fabrication and Luminescence Properties of Transparent Glass‐Ceramics Containing Eu3+‐Doped TbPO4 Nanocrystals

Eu³⁺‐doped transparent phosphate precursor glasses and glass‐ceramics containing TbPO₄ nanocrystals were successfully fabricated by a conventional high‐temperature melt‐quenching technique for the first time. The formation of TbPO₄ nanocrystals was identified through X‐ray diffraction, transmission electron microscopy, high‐resolution transmission electron microscopy, selected‐area electron diffraction, and photoluminescence emission spectra. The obvious Stark splitting of ⁵D₀‐⁷F_J (J = 1, 2, 4) transitions of Eu³⁺and the increase of internal quantum efficiency indicate the incorporation of Eu³⁺ into TbPO₄ nanocrystals. Energy transfer from Tb³⁺ ions to Eu³⁺ ions was investigated using excitation and emission spectra at room temperature. The glass‐ceramics obtained have more efficient Tb³⁺ to Eu³⁺ energy transfer than the glass, and so serve as good hosts for luminescent materials.     

Investigation of Eu2+ luminescence in barium tetraphosphate Ba3P4O13 polycrystalline ceramics

In this paper, Ba₃P₄O₁₃:Eu²⁺ phosphor was synthesized by a solid-state reaction. The photoluminescence (PL) emission spectrum and luminescence decay kinetics confirm that the doped Eu²⁺ ions can occupy two different Ba²⁺ sites. The PL excitation spectrum shows a broad band matching well with the emission of near-UV chip. Ba₃P₄O₁₃:Eu²⁺ is a promising phosphor for near-UV chip excited white LEDs. The doped Eu³⁺ ions can also be reduced to Eu²⁺ ions in air atmosphere at high temperature. Charge compensation mechanism is applied to explain this kind of abnormal reduction.     

Spectroscopic investigations on high efficiency deep red-emitting Ca2SiO4:Eu3+ phosphors synthesized from agricultural waste

Europium doped calcium orthosilicate (Ca₂SiO₄) phosphors have been synthesized by the conventional high temperature solid-state reaction method in various concentrations from agricultural waste (egg shell as a CaO and rice husk as a SiO₂). These phosphors structure from X-ray diffraction and morphology from scanning electron microscopy have been examined. Concentration dependent Eu³⁺ ions luminescent properties in Ca₂SiO₄ phosphors have been studied from the excitation, emission and decay curves analysis. The ⁵D₀ → ⁷F_J transitions observed in luminescence spectrum allows to determine the site symmetry of the Eu³⁺ ion. A charge transfer band (CTB) at around 260?nm which is due to the Eu–O interaction in the host along with the 4f – 4f excitation bands due to Eu³⁺ ions in UV and blue regions are observed. The color co-ordinates determined from emission spectra varies with concentrations of Eu³⁺ ions and are found to fall in the red region. The decay curves show single exponential behavior for all concentrations of Eu³⁺ ions (0.01–0.4?mol%) and the lifetimes varied from 2.67 to 2.78?ms. It is worth noting that the present material is found to be far better than many red phosphors synthesized by using agricultural waste as raw materials.     

Impact of Eu3+ Dopants on Optical Spectroscopy of Ce3+: Y3Al5O12‐Embedded Transparent Glass‐Ceramics

Transparent glass‐ceramics containing Ce³⁺: Y₃Al₅O₁₂ phosphors and Eu³⁺ ions were successfully fabricated by a low‐temperature co‐sintering technique to explore their potential application in white light‐emitting diodes (WLEDs). Microstructure of the sample was studied using a scanning electron microscope equipped with an energy dispersive X‐ray spectroscopy. The impact of co‐sintering temperature, Ce³⁺: Y₃Al₅O₁₂ crystal content and Eu³⁺ doping content on optical properties of glass‐ceramics were systematically studied by emission, excitation spectra, and decay curves. Notably, the spatial separation of these two different activators in the present glass‐ceramics, where Ce³⁺ ions located in YAG crystalline phase while the Eu³⁺ ones stayed in glass matrix, is advantageous to the realization of both intense yellow emission assigned to Ce³⁺: 5d→4f transition and red luminescence originating from Eu³⁺: 4f→4f transitions. As a result, the quantum yield of the glass‐ceramic reached as high as 93%, and the constructed WLEDs exhibited an optimal luminous efficacy of 122 lm/W, correlated color temperature of 6532 K and color rendering index of 75.     

Effect of Crystallite Size and Crystallinity on Photoluminescence Properties and Energy Transfer of Y6MoO12:Eu

The phosphors Y₆MoO₁₂:Eu³⁺ have been synthesized via citrate complexation method at different calcination temperatures. The evolutions of the crystal structure and the photoluminescence (PL) properties were characterized by means of powder X‐ray diffraction (XRD), Raman and PL spectra, respectively. It was revealed that a red emission could be obtained via three excitation channels, namely f–f transition of Eu³⁺ ions, charge‐transfer transition from O² to Eu³⁺, and interband transition (IBT) of MoO₆ groups. The PL spectra and their temporal decay character of Eu³⁺ ions depended on both crystal structure and excitation channel. The emission reduced with the crystallite size when Eu³⁺ ions were excited directly, but the emission evolved in a different model with the host lattices were excited. The effect of grain boundary and other lattice defect on the energy transfer and dissipation within the phosphors were discussed.     

Energy Transfer Study on Dense Eu3+/Tb3+‐Coactivated Oxyfluoride Borogermanate Scintillating Glasses

Tb³⁺‐, Eu³⁺‐activated, and Eu³⁺/Tb³⁺‐coactivated oxyfluoride borogermanate scintillating glasses with the density of about 6.50 g/cm³ were successfully synthesized by a melt‐quenching method. The structure and optical properties including transmittance, photoluminescence (excitation and emission spectra), photoluminescence decay, and X‐ray excited luminescence behaviors were studied in detail. Our results reveal that the energy‐transfer efficiency from Tb³⁺ to Eu³⁺ ions increases with an increase in Eu³⁺ concentration. The energy‐transfer mechanism is also discussed by Dexter's and Reisfeld's semiexperimental methods.     

Microstructure of Eu3+‐Doped Perovskites‐Type Niobate Ceramic La3Mg2NbO9

Eu³⁺‐doped red‐emitting ceramics of Eu³⁺‐doped La₃Mg₂NbO₉ were prepared via typical solid state. X‐ray diffraction and scanning electron microscope were utilized to characterize the ceramics. The photoluminescence excitation and emission spectra, the fluorescence decay curves, and color coordinates were investigated. The concentration quenching of the samples were discussed as well. The microstructures of the ceramics were discussed according to the spectral properties of probe ions of Eu³⁺, for example, substitution sites for Eu³⁺, inhomogeneous broadening and splitting of the emission bands, nonexponential decay, ⁵D₀→⁷F₀ emission transition, distorted symmetry sites, etc. The crystal structure of La₃Mg₂NbO₉ is heavily distorted due to the mixed occupation of Mg and Nb on B sites. Eu³⁺ ions only substitute La³⁺ sites and Eu³⁺ ions (or rare‐earth ions) are arranged in the heavily disordered environments over the whole structure in La₃Mg₂NbO₉.     

A novel tunable green-to-red emitting phosphor Ca4LaO(BO3)3:Tb,Eu via energy transfer with high quantum yield

A novel green phosphor composed of Ca₄LaO(BO₃)₃:Tb³⁺ (CLBO:Tb) has been synthesized by a combustion method with urea. Its crystal structure, temperature-dependent luminescence, and quantum yield (QY) have been characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectra with heating device and integrate sphere. No concentration quenching has been observed when all of La³⁺ ions are substituted with Tb³⁺ ions. Green phosphor Ca₄TbO(BO₃)₃ (CTBO) has 200% luminescence intensity of commercially available phosphor LaPO₄:Ce, Tb (LPO:Ce, Tb) under 378 nm excitation. The QY of CTBO is as high as 98%. Through a Dexter energy transfer mechanism, Eu³⁺ ions are efficiently sensitized by Tb³⁺, resulting in an emission with color tunable from green to red under ultraviolet excitation. A possible mechanism of energy transfer from Tb³⁺ to Eu³⁺ has been investigated by PL spectra and decay measurements. The energy transfer efficiency from Tb³⁺ to Eu³⁺ increases linearly with concentration of Eu³⁺ increasing.     

Synthesis and Structural Probing of Eu3+ Doped BaYF5 Nano-Crystals in Transparent Oxyfluoride Glass-Ceramics

Transparent oxyfluoride glass-ceramics containing Eu: BaYF₅ nano-crystals in the newly developed SiO₂–K₂CO₃–BaF₂–YF₃–Sb₂O₃ glass system are synthesized by melt quenching method followed by optimized ceramization process. The X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy confirmed the precipitation of tetragonal BaYF₅ nano-crystals in glass matrix. The coexistence of Eu²⁺ and Eu³⁺ ions in both glass and glass-ceramics are ascertained from their emission and excitation spectra. The in situ formation of divalent europium (Eu²⁺) along with Eu³⁺ during high temperature synthesis under ambient atmosphere is explained through optical basicity model. The Eu³⁺ emission from upper excitation states (⁵D₃₋₁) and reduced asymmetry ratio (R = I_ED/I_MD) in glass-ceramics have established the dopant ion incorporation into fluoride nano-crystalline environment. The observed luminescence properties of Eu:BaYF₅ are compared with that of Eu:BaYF₅ nanocrystals containing transparent glass-ceramics and their marked differences are discussed.     

Luminescence of Eu‐Doped Transparent LuPO4 Glass‐Ceramics

Dual valence Eu‐doped transparent glass‐ceramics containing LuPO₄ nanocrystals were fabricated by melt‐quenching technique in air atmosphere. Their luminescent properties were systematically investigated by excitation, emission spectra, and decay lifetime measurements. The prominent Stark splitting, low forced electric‐dipole ⁵D₀ – ⁷F₂ transition and long decay lifetimes of Eu^{3 +} emission for glass‐ceramics reveal the incorporation of Eu^{3 +} into LuPO₄ nanocrystals. The enhanced Eu^{2 +} emission and reduction mechanism of Eu^{3 +} to Eu^{2 +} after crystallization are discussed briefly. Our results indicate that transparent LuPO₄ glass‐ceramics may find applications in photonics.     

Synthesis,energy transfer mechanism,and tunable emissions of novel Na3La(VO4)2:Re3+ (Re3+ = Dy3+, Eu3+, and Sm3+) vanadate phosphors for near-UV-excited white LEDs

In this study, novel Eu³⁺-, Dy³⁺-, and Sm³⁺-activated Na₃La(VO₄)₂ phosphors were synthesized using a solid state reaction method. X-ray diffraction analysis results indicated that the Na₃La(VO₄)₂ phosphors had an orthorhombic crystal structure with the Pbc21 space group. There were two different La(1)O₈ and La(2)O₈ polyhedra with high asymmetry in the crystal structure. Scanning electron microscopy revealed that the product had a sheet morphology with an irregular particle size. Further, the luminescence properties, including the excitation and emission spectra, and luminescence decay curve, were investigated using a fluorescence spectrometer. The results showed that the Na₃La(VO₄)₂ compound was an excellent host for activating the luminescence of Eu³⁺ (614 nm), Dy³⁺ (575 nm), and Sm³⁺ (647 nm) ions. Further, Dy³⁺/Eu³⁺ co-doped Na₃La(VO₄)₂ phosphors were exploited, and the energy transfer from Dy³⁺ to Eu³⁺ was demonstrated in detail by the photoluminescence excitation, photoluminescence spectra, and luminescent decay curves. The results showed that the energy transfer efficiency from Dy³⁺ to Eu³⁺ was highly efficient, and the energy transfer mechanism was dipole–dipole interactions. Finally, tunable emissions from the yellow region of CIE (0.3925, 0.4243) to the red region of CIE (0.6345, 0.3354) could be realized by rationally controlling the Dy³⁺/Eu³⁺ concentration ratio. These phosphors may be promising materials for the development of solid-state lighting and display systems.     

Color-tunable and white emission of Tm3+ doped transparent zinc silicate glass-ceramics embedding ZnO nanocrystals

Tm³⁺ doped zinc silicate glass-ceramics composed of SiO₂-Al₂O₃-ZnO-K₂O-Tm₂O₃ embedded with ZnO nanocrystals were successfully fabricated by melt-quenching method with subsequent heat treatment. Tm³⁺ ions and ZnO nanocrystals were introduced as blue and yellow luminescence centers, respectively. The effects of heat treatment, excitation wavelength and Tm³⁺ doping concentration on the photoluminescence behaviors of these glass-ceramics were studied. Short-time (5 minutes) heat treatment was considered as the optimal heat treatment time, which facilitates simultaneously emitting narrow blue peak located at 453 nm and a broad yellow band centered at 580 nm. Blue and yellow emissions could be attributed to the ¹D₂ → ³F₄ transition of Tm³⁺ and Zn_i/O_i-related defect emission of ZnO nanocrystals, respectively. The combination of these two emissions allows the realization of white light emitting in the glass-ceramic samples. Furthermore, tunable luminescent color and chromaticity coordinates, including yellow, white and blue, can be realized by varying the pumping wavelengths as well as the content of Tm³⁺ dopant in the glass matrix. Nearly perfect white light emission with Commission Internationale de l'Eclairage coordinate (x = 0.33, y = 0.32) was achieved for the 0.05 mol% Tm³⁺ doped glass-ceramic embedding ZnO nanocrystals by heat treatment at 750°C for 5 minutes under the excitation of 360 nm. These luminescent glass-ceramics doped with Tm³⁺ ion and ZnO nanocrystals could be a promising candidate for white light emitting devices under near-ultraviolet excitation.     

Eu2+‐Doped Yellow‐Emitting CsBaB3O6 Glass‐Ceramic Prepared by Melt Quenching and Re‐Crystallization Method

Eu³⁺‐doped cesium barium borate glass with the composition of Cs₂O·2BaO·3B₂O₃ was prepared by the conventional melt quenching method. The glass‐ceramic sample was obtained from the re‐crystallization of the as‐made glass to change the amorphous glass into a crystalline host. This reduces the Eu³⁺ in glass to Eu²⁺ ions resulting in a yellow‐emitting phosphor of Eu²⁺‐activated CsBaB₃O₆. The samples were investigated by the XRD patterns and SEM micrograph, the optical absorption, the photoluminescence spectra, and decay curves. The as‐made glass has only Eu³⁺ centers. Under the excitation of blue or near‐UV light, Eu²⁺‐doped CsBaB₃O₆ presents yellow‐emitting color from the allowed inter‐configurational 4f–5d transition in the Eu²⁺ ions. The maximum absolute luminescence quantum efficiencies of Eu²⁺‐doped CsBaB₃O₆ phosphor was measured to be 47% excited at 430 nm light at 300 K. By taking into account the efficient excitation in blue wavelength region, this new phosphor could be a potential yellow‐emitting phosphor for an application in white light‐emitting diodes fabricated with blue chips.     

The luminescence spectroscopy and thermal stability of red-emitting phosphor Ca9Eu(VO4)7

Eu-based vanadate Ca₉Eu(VO₄)₇ phosphor was synthesized by the solid state reaction method and was characterized by X-ray powder diffraction (XRD). The photoluminescence excitation and emission spectra, fluorescence decay curves and the dependence of luminescence intensity on temperature were investigated. The phosphor can be efficiently excited by near UV light to realize an intense red luminescence (614 nm) corresponding to the electric dipole transition ⁵D₀ → ⁷F₂ of Eu³⁺ ions. The crystallographic site-occupations of the Eu³⁺ ions in Ca₉Eu(VO₄)₇ were investigated by the site-selective excitation and emission spectra, and the fluorescence decay curves in the ⁵D₀ → ⁷F₀ region using a pulsed, tunable, narrowband dye laser. The red luminescence together with the thermal stability was discussed on the base of the Eu³⁺ site-distribution in Ca₉Eu(VO₄)₇ host.