Optimal Eu3 Research Articles

Synthesis and optical properties of highly efficient Na7Mg13La(PO4)12:Eu3+ powders with excellent thermal stability

In the pursuit of efficient red-emitting phosphors, a series of red-emitting Na7Mg13La(PO4)12:Eu3+ phosphors was prepared using a high-temperature solid-state synthesis method. The phase purity was monitored using powder X-ray diffraction (XRD). The morphological features of the synthesized samples were evaluated by taking scanning electron microscopy (SEM) images. The optical properties of the synthesized polycrystalline samples were investigated by recording room-temperature and temperature-dependent (77–500 K interval) excitation and emission spectra, and photoluminescence (PL) decay curves. The calculated TQ1/2 values were above 420 K, regardless of the Eu3+ concentration, indicating the high thermal stability of the phosphors. The optimal Eu3+ concentration was 100 %, which indicated the absence of concentration quenching in the given host. Furthermore, the quantum efficiency of fully Eu3+-substituted compound reached 100 %, which is an excellent feature for practical phosphor applications.

Judd‐Ofelt analysis and optical properties of Eu3+‐doped GdPO4 phosphors synthesized by combustion method

AbstractThe Eu3+‐doped GdPO4 nanoparticles were prepared via a straightforward combustion method using urea as fuel and nitrates as a precursor. X‐ray powder diffraction patterns, infrared spectrum (IR), HR‐TEM, photoluminescence (PL), phonon sideband and photoluminescence excitation (PLE) were researched. There is a phase transition from the hexagonal phase into the monoclinic phase when the calcined temperature is over 700 °C. All of phosphors have similar morphology and the average diameters for nanoparticles are 20–30 nm. Under the excitation at 273 nm, GdPO4:Eu3+ powders showed red emission bands originating from the 5D0–7FJ (J = 1, 2, 3 and 4) transitions of Eu3+. The orange‐red emission (5D0–7F1 transition) is dominated because the Eu3+ ions exist with inversion symmetry in the lattice. The study suggests that the optimal Eu3+ ions concentration is 5 mol%. In addition, the second order crystal field parameter (B20) and the influence of concentration of Eu3+ ions on decay time are also mentioned, the intensity parameters (Ω2,4,6) and quantum efficiency were determined based on Judd‐Ofelt theory.

Structural and luminescence properties of novel Eu3+-doped Na3Ba2LaNb10O30 phosphors with high quantum efficiency and excellent color purity for w-LED applications.

In this study, we report the successful synthesis and thorough characterization of Eu3+-doped Na3Ba2LaNb10O30 phosphors, targeting their application in white-light-emitting diodes (w-LEDs). The phosphors were synthesized using a high-temperature solid-state method, ensuring robust incorporation of Eu3+ ions into the host lattice. Comprehensive analyses were performed, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy, confirming the phase purity, crystallinity, morphology, and elemental composition of the phosphors. We have also studied the electronic structure using diffuse reflectance spectroscopy (DRS). Photoluminescence studies revealed strong red emissions under near-ultraviolet light excitation, with the optimal Eu3+ doping concentration identified to be 9 mol%. Quantum-yield measurements demonstrated high luminescence efficiency, while chromaticity coordinates indicated excellent color purity suitable for w-LED applications. These findings contribute significantly to the advancement of phosphor materials for solid-state lighting, suggesting promising prospects for their integration into commercial LED devices.

Novel Eu3+-activated Ca3Ga2Ge4O14 red-emitting phosphors with high quantum efficiency for plant growth lighting and white LEDs.

In recent years, rare-earth-based phosphors for near-ultraviolet (NUV)-triggered white light emitting diodes (w-LEDs) have become a research hotspot. However, it is still not possible to obtain phosphors with high quantum yield, excellent color purity and multiple applications. Hence, a series of novel Eu3+-activated Ca3Ga2Ge4O14 (CGG) red-emitting phosphors with high quantum efficiency, excellent color purity and good thermal stability were prepared by a high-temperature solid-phase method. All the CGG:Eu3+ phosphors emitted dazzling red emission with excitation at 394 nm. The optimal Eu3+ doping concentration of compounds was 12% with an excellent color purity of 97.89%, and the concentration quenching mechanism was investigated as dipole-dipole interactions. Meanwhile, the synthetic samples exhibited good thermal stability with the activation energy of 0.26 eV. Remarkably, the internal quantum yield of the prepared phosphors reaches 94.26%. Furthermore, the emission spectra of the prepared red-LEDs overlap considerably with the absorption spectra of PR and PFR required for plant growth. The w-LED device emits warm white light with a high color rendering index of 91.64 and an appropriate correlated color temperature of 4808 K. These excellent luminescence properties indicate that the prepared CGG:Eu3+ phosphors exhibit extensive potential for applications in plant growth lighting and white LEDs.

High concentration Eu3+ doped yttria-stabilized zirconia ceramics

The series of yttria-stabilized zirconia (YSZ) ceramics doped with high Eu3+ ions concentration (up to 15 wt%) were successfully fabricated by Spark Plasma Sintering (SPS) technique for the first time. The effect of europium concentration and atmospheric annealing on the optical, structural, and luminescent properties has been studied in detail. The combination of XRD and EDS data allows to find two phases in tested YSZ:Eu ceramics such as ZrO2 and Zr2O. The highest transmission values were achieved about 63% at 600 nm for the 10 wt% of Eu2O3 doped YSZ ceramics without annealing. When the annealing temperature changes from 1300° to 1600°C the transmission values increase to 70%. An analysis of the photoexcitation and photoluminescence spectra showed that the main excitation bands are determined by the direct excitation of the 7F0 ground state to higher 4 f levels with following radiation transitions in Eu3+ ions. The optimal Eu3+- dopant concentration in YSZ ceramics was established and the process of emission quenching was discussed. The luminescence decay kinetics are approximated by the single or sum of two exponential functions in dependence of Eu3+ ions concentrations.

Photoluminescence studies of Eu3+ doped bismuth silicate based phosphor for plant grow LEDs

Artificial red lights of good quality are essential for indoor plant growth as it has a wide spectrum effects on photosynthesis rate and photomorphogenic processes of organic plant growth cycle. In present work we report on Eu3+ doped Bi4Si3O12 (BSO) phosphor for spectroscopic implication in smart plant grow LEDs. Eu3+ activated series of Bi4Si3O12 phosphor have been prepared via traditional solid-state reaction method. Crystal structure and phase formation characterization is determined by using X-ray diffraction (XRD). Photoluminescence spectra of prepared phosphor shows broad excitation spectra ranging from 200 to 530 nm. The optimal Eu3+ doping concentration observed at 3 mol%. Emission spectra observed under the excitation of 270 nm shows broad emission band at 469 nm along with other characteristic peak at 500 nm-710 nm. Observed emission peaks at 622 nm, 656 nm and 702 nm were chosen opt for plant grow lights. The phytochrome PFR absorption spectra of plants matches well with the emission band of our Eu3+ doped BSO phosphor and can be considered as a viable choice for solid state lighting and plant grow light LEDs.

Photoluminescence of Eu3+ in silicate-based phosphors by near-infrared and near-ultraviolet excitation for multifunctional applications

In this work, a series of Eu3+/Yb3+ doped La1.55SiO4.33 (LSO) phosphors were prepared by solid state reaction method for multifunctional applications. The phase purity and particle morphology were characterized with XRD and SEM technique, respectively. Upon ultraviolet light excitation, the downshifting luminescence of Eu3+ was observed in the red region, and the strongest emission peak located at 612 nm is attributed to the forced electric dipole 5D0→7F2 transition. The optimal Eu3+ doping concentration was determined to be 20 mol%, for which the internal quantum efficiency of the phosphor reaches 75.1%. The temperature-dependent emission spectra of LSO:20%Eu3+ revealed that the quenching temperature T0.5 is 483 K. For the upconversion (UC) luminescence, the Yb3+-Eu3+ codoped LSO phosphors were designed, where the Yb3+ ion was used as a sensitizer. The UC mechanism for a cooperative energy transfer was learnt from the pump-power-dependent emission spectra. By excitation at various temperatures, the intensities of emissions from different excited states showed different changes with temperature. All the above spectral characteristics indicate that the LSO:Eu3+/Yb3+ phosphors can show potential applications in LEDs, anticounterfeiting and optical thermometer.

A new Milarite type KMLS:Eu3+ orange-red-emitting phosphor for pc-white LEDs and Forensic applications

In this article, we present the synthesis and characterization of Eu3+-activated KMLS:Eu3+ phosphor for pc-WLEDs, latent fingerprint detection, and security ink applications. The structural phase, luminescent property, and colour purity of the as-prepared phosphor were investigated. XRD profiles and Rietveld refinement analysis confirm the hexagonal crystal system of the as-prepared phosphor. Concentration quenching effect was not observed up to 17 mol% of Eu3+. The site occupancy preferences of Eu3+ were investigated using the bond-valence model. The CIE-coordinate of optimal Eu3+ is estimated to be close to the standard NTSC value, and color purity is found to be above 90% for all the Eu3+ concentrations. Both Judd-Ofelt (J-O) analysis and asymmetric ratios revealed that the local environment around Eu3+ is asymmetric in nature. The radiative properties, including the stimulated emission cross section and optical gain parameters, of the highest concentration of Eu3+ (17mol%) were determined. Further, the results of thermal quenching analysis show that 91% of the luminescence intensity can be maintained at 150 °C, demonstrating good thermal stability. The multilevel ridge characteristics of the latent fingerprint stained with as-prepared phosphor could be clearly visualized under 254 nm UV excitation. All of the above results indicate that as-prepared phosphor materials can be suitable for use in forensic applications as well as solid state lighting applications.

Broadband UV-Excitation and Red/Far-Red Emission Materials for Plant Growth: Tunable Spectrum Conversion in Eu3+,Mn4+ Co-doped LaAl0.7Ga0.3O3 Phosphors.

Broadband ultraviolet (UV) excitation and red/far-red emission phosphors can effectively convert solar spectrum to enhance photosynthesis and promote morphogenesis in plants. Based on the above application requirements, Eu3+ single-doped LaAl1-yGayO3 solid solutions and Eu3+,Mn4+ codoped LaAl0.7Ga0.3O3 phosphors were designed and synthesized in this work. The LaAl0.7Ga0.3O3:0.05Eu3+ (LAG:Eu3+) phosphor exhibits a strong charge transfer band (CTB) excitation and characteristic 5D0 → 7F2 transition red emission (619 nm), which is very similar to the luminescence properties of Eu3+-organic ligand compound (EuL3). Rietveld refinement studies further revealed that the cation substitution disturbs the site symmetry. The optimal Eu3+, Mn4+ co-doped LaAl0.7Ga0.3O3 (LAG:Eu,Mn) phosphor possesses a dual-band excitation spectrum in broadband ultraviolet (UVA, UVB) area and a dual-band emission spectrum within red/far-red area. Under the sunlight radiation, the real-time spectrum of luminous laminated glasses fabricated by coating the LAG:Eu,Mn phosphor shows the percentage of radiant intensity in the red/far-red region significantly increases, suggesting that the phosphor can be a promising candidate for solar spectral conversion in plant cultivation. We believe this work provides a new idea for developing novel broadband ultraviolet excitation and red/far-red emission phosphors.

High quantum efficiency and excellent color purity of red-emitting Eu3+-heavily doped Gd(BO2)3-Y3BO6-GdBO3 phosphors for NUV-pumped WLED applications.

Eu3+-doped phosphors have been much attractive owing to their narrow-band red emission peak at 610-630 nm with high color purity; however, the weak and narrow absorption band in the NUV region limits their applications. Doping a higher amount of Eu3+ ions into a non-concentration quenching host could be key to enhancing the efficiency of the absorption value and emission intensity. Hence, the design of Eu3+-heavily doped phosphors with a suitable host lattice is key for applications. In this study, red-emitting Eu3+-doped Gd(BO2)3-Y3BO6-GdBO3 (GdYGd:Eu3+) phosphor with a high quantum efficiency of 58.4% and excellent color purity of 99.5% is reported for the first time. The phosphor is efficiently excited by NUV light at 394 nm and emits a strong red emission band in the 590-710 nm range, peaking at 612 nm. The optimal annealing temperature and Eu3+ doping content to obtain the strongest PL intensity are 1100 °C and 20 mol%, respectively. The optimized GdYGd:Eu3+ phosphor possesses a high activation energy of 0.319 eV and a lifetime of 1.14 ms. An illustration of phosphor-coated NUV LED with chromaticity coordinates (x = 0.5636,y = 0.2961) was successfully synthesized, demonstrating the great potential of GdYGd:Eu3+ phosphor for NUV-pumped WLED applications.

Luminescence properties, tunable emission and energy transfer of Ca9MgLi(PO4)7:Bi3+/Eu3+ phosphor

Bi3+, Eu3+ singly doped and Bi3+/Eu3+ co-doped Ca9MgLi(PO)7 (CMLPO) with a single pure phase are synthesized in air by high-temperature solid-state method and their crystal structure and the luminescence properties are investigated. CMLPO:Bi3+ with excitation at 313 nm shows blue emission. CMLPO:Eu3+ with excitation at 318 and 394 nm emits red emission. CMLPO:Eu3+, Bi3+ with excitation at 318 nm shows an adjustable color emission when the ratio between Eu3+ and Bi3+ ions is changed. CMLPO:Eu3+, Bi3+ under excitation 394 nm only emits a single red color light. The optimal Eu3+ concentration in CMLPO:Eu3+ and Bi3+ concentration in CMLPO:8 mol%Eu3+, Bi3+ are ∼8 mol% and 2 mol%, respectively. The luminescence intensity of CMLPO:Eu3+ can be enhanced 1.4–2.2 times when Bi3+ ion as sensitizer is co-doped into CMLPO:Eu3+. The energy transfer process in CMLPO:Eu3+, Bi3+ is observed and analyzed. The luminous mechanisms of samples are explained by using the energy level diagrams of Eu3+ and Bi3+ ions. The research in this paper offers effective guidance for the optical property improvement of phosphors by co-doping other ions as sensitizer.

Dual luminescence optimization of Ho3+/Yb3+/Eu3+-doped Gd2O3 phosphor prepared by spray pyrolysis for anti-counterfeiting application

Ho3+/Yb3+/Eu3+-doped Gd2O3 spherical particles with upconversion (UC) and down-conversion (DC) emission were synthesized by spray pyrolysis. The resulting phosphor showed intense DC red and UC green emissions. The Eu3+, Ho3+ and Yb3+ contents were optimized to simultaneously achieve the highest UC and DC emission. Resultantly, the optimal Eu3+, Ho3+ and Yb3+ doping concentrations were found as 0.2%, 3.0% and 0.2%, respectively. The green UC emission resulted from a typical two-photon process, and the UC and DC emission intensity showed a linear relationship with crystallite size. The microstructure of Gd2O3:Ho3+/Yb3+/Eu3+ was controlled by introducing organic additives into the spray solution. The use of organic additives made it possible to improve crystallinity having a dense morphology, which led to largely enhance the DC and UC intensity. The prepared Gd2O3:Ho3+/Yb3+/Eu3+ spherical particles showed excellent dual luminescence suitable as anti-counterfeiting security materials.

On the structures and luminescence properties of Eu3+ -doped Li2 CaGeO4 , Ca2 GeO4 , and Ca5 Ge3 O11 compounds.

Powder samples of Li2 CaGeO4 , Ca2 GeO4 , and Ca5 Ge3 O11 doped by 0.5, 1, 2, 3, 4 and 5 at% Eu3+ relative to the Ca2+ , were prepared using a conventional solid-state synthesis technique. X-ray diffraction (XRD) analyses confirmed obtaining the pure phases at all dopant concentrations. In parallel, single crystals of the three compounds with the experimentally found optimal Eu3+ concentration were grown using a flux method. Structural investigation on the single crystals were done with a special attention to the form of the Ca-O polyhedron, the mean Ca-O distance, the Ca-Ca distance in the structure, the distortion degree of the polyhedron, as well as the Eu-Ca substitution site. The main spectral characteristics were analyzed and several relationships between the structural and spectra features were found. The optimal dopant concentration was 3 at% for Ca2 GeO4 and 4at% for Ca5 Ge3 O11 and Li2 CaGeO4 . Commission Internationale de l'éclairage coordinates of the samples showed emission colours in the red region close to the standard red coordinates and slightly influenced by the active ion concentration. The obtained results showed that europium-doped Li2 CaGeO4 , Ca2 GeO4 , and Ca5 Ge3 O11 could be used as red phosphors.

Establishment of a time-resolved immunoassay for acute kidney injury based on the detection of Kim-1.

AimTo establish a highly sensitive time‐resolved fluorescence immunoassay (TRFIA) of kidney injury molecule‐1 (Kim‐1) and evaluate its clinical value in acute kidney injury (AKI).MethodsThe Kim‐1‐TRFIA was established by the double‐antibody sandwich method, and the method was evaluated. The established Kim‐1‐TRFIA was used to detect the concentration of Kim‐1 in the serum of healthy controls and patients with AKI.ResultsThe optimal coating antibody concentration and optimal Eu3+‐labeled antibody dilution ratio for Kim‐1‐TRFIA are 1 μg/ml and 1:140, respectively. The linear range is 42.71–4666.69 pg/ml. The intra‐ and inter‐assay coefficients of variation are <10%. The specificity of our Kim‐1‐TRFIA is acceptable. The recovery is between 95.14% and 102.84%. The concentration of Kim‐1 in the serum of patients with AKI is 126.50 ± 67.99 pg/ml, which is significantly higher than that in the serum of healthy controls (49.72 ± 16.40 pg/ml, p < 0.001). Staging patients with AKI by glomerular filtration rate shows that the serum concentration of Kim‐1 increases significantly with increasing disease severity (p < 0.05).ConclusionA highly sensitive Kim‐1‐TRFIA was established. With this immunoassay, a good differential diagnosis can be made, and healthy people and AKI patients can be differentiated by detecting the concentration of Kim‐1 in the serum. Moreover, the severity of AKI patients can be determined.

Study on luminescence characterizations of SrMg2La2W2O12:Eu3+ red-emitting phosphor

SrMg2La2W2O12:Eu3+ (SMLWO:Eu3+) phosphors are successfully synthesized via the high temperature solid-state method in air. We study the crystal structure and luminescence properties (e.g. the excitation and emission spectra, the concentration dependent spectra, and fluorescent lifetimes) of the samples. SMLWO:Eu3+ phosphor with excitation at 324, 396, and 466 nm emits red light due to the 5D0 → 7F0, 7F1, 7F2, 7F3, 7F4, and 7F5 transitions of Eu3+ ion. We investigate the influence of excitation wavelength and Eu3+ concentration on the luminescence properties of the samples. We confirm the optimal Eu3+ concentration (∼8 mol%) in SMLWO:Eu3+ phosphor via the concentration dependent emission spectra of samples, and explain the luminous mechanism of SMLWO:Eu3+ phosphor by using the energy level diagram and energy transfer of Eu3+ ion.

Effects of the Pechini's modified synthetic route on structural and photophysical properties of Eu3+ or Tb3+-doped LaAlO3

Herein, it is reported the Pechini's synthesis of LaAlO3:Ln3+ (Ln = Eu3+ or Tb3+) varying doping concentration from 1 to 9 at.% to evaluate its influence on structure and luminescence. Sub-micrometric, high-crystalline and monophasic samples with crystallite size smaller than 61 nm were synthesized with activators replacing slightly-distorted LaO12 polyhedra, and occupying two non-equivalent local sites on the surface, and inside them. Upon UV excitation, Eu3+-doped phosphors emit at 620 nm while Tb3+ ones exhibit dominant wavelength within the green spectral region. The excited state lifetimes lie within 2.5–3.4 ms, and as doping percentage increases, luminescence quenching mediated by exchange coupling energy transfer occurs, leading to the 3 and the 7% as the optimal Eu3+ and Tb3+concentrations, respectively. Finally, our proposed route increases the Eu3+ 5D0→7F2 transition relative intensity, compared with others reported, ensuring that this method brings a breakthrough in the optical performance of LaAlO3-based phosphors.

A new solid solution Bi1.48Eu0.52Pb0·5Sr0·5B2O7 and luminescent properties of the Bi2-xPb0.5Sr0·5B2O7:xEu3+ phosphors

A new solid solution Bi1.48Eu0.52Pb0·5Sr0·5B2O7 was prepared by the high-temperature solid state reaction at 850 °C and its crystal structure was determined by single-crystal XRD analysis with following crystal data: R3¯c, a = 9.0085(2) Å, c = 38.8910(9) Å, V = 2733.26(13) Å3 and Z = 18. It has a layered structure in which alternating [BO3]3- triangles and [(Pb/Sr)O6]10− trigonal prisms are connected via common O vertexes to generate a 2D layer, with [(Bi/Eu)2O]4+ groups located in the six-membered ring channels within the layer. Two 3¯ axis related layers are stacked rhombohedrally along the c-axis to build a unit cell and held together by weak (Bi/Eu)-O bonds. The existence of BO3 groups was confirmed by vibrational spectroscopy, the optical band gap was determined with the UV–vis absorption measurements, and the chemical states of the elements were analyzed by XPS spectroscopy. Furthermore, the Bi2-xPb0.5Sr0·5B2O7:xEu3+ (0.10 ≤ x ≤ 0.50) phosphors were synthesized via the solid-state reaction method and their photoluminescence properties were studied. The emission spectra consist of groups of peaks in the red spectral region due to 5D0→7Fj (j = 0, 1, 2, 3) electronic transitions of Eu3+ ions and the optimal Eu3+ content was found to be x = 0.3. The CIE coordinates of the Bi1.70Eu0.30Pb0·5Sr0·5B2O7 phosphor was obtained to be (0.640, 0.359) and the QE value was equal to 15.41%. Moreover, its synthetic temperature is low. The characteristics make the Bi2-xPb0.5Sr0·5B2O7:xEu3+ (0.10 ≤ x ≤ 0.50) compounds to be promising reddish-orange phosphors for white LEDs.

High Quantum Yield Gd4.67Si3O13:Eu3+ Red-Emitting Phosphor for Tunable White Light-Emitting Devices Driven by UV or Blue LED

Eu3+-activated oxide components appear as a kind of rare-earth red phosphors that can be used for warm white light-emitting diode (LEDs). At present, it is still a challenge to synthesize oxide-component phosphors with high photoluminescence quantum yields compared to those of nitride and fluoride red phosphors. Herein, we propose a kind of Eu3+-activated Gd4.67Si3O13 rare-earth silicate phosphor by the convenient high-temperature solid reaction method. These designed phosphors can be effectively excited by either 394 nm near-ultraviolet light or 465 nm blue light and then emit red light at a dominant wavelength of 615 nm. Particularly, for the optimal Eu3+-concentration-activated Gd3.67EuSi3O13 phosphor, photoluminescence quantum yields are measured to be above 80%, which is superior to that of the general rare-earth oxide salt phosphor and comparable to that of commercial rare-earth nitride red phosphors such as Ca-α-SiAlON:Eu2+ (QY = 70.5%) and CaAlSiN3:Ce3+ (QY = 80%). Packaged with commercial yellow phosphor Ce3+:YAG and UV or blue LED chip, our red component serves to improve the CRI and CCT for the tunable white light-emitting devices. Moreover, the phosphor has good thermal cycling stability with a thermal-quenching activation energy of 0.28912 eV. Finally, the temperature-dependent properties make the Gd4.67Si3O13:Eu3+ phosphors have potential application in optical temperature measurement systems. The maximum relative sensitivity Sr is found to be 1.05 × 10–2 K–1 at 456 K.

Novel fluorescent nano-sensor based on amino-functionalization of Eu3+:SrSnO3 for copper ion detection in food and real drink water samples.

Lanthanide-doped nanoparticles exhibit unique optical properties and have been widely utilized for different sensing applications. Herein, the Eu3+:SrSnO3@APTS nanosensor was synthesized and its optical properties were analyzed using UV-Vis and photoluminescence spectroscopy. The TEM images of the synthesized nanophosphor Eu3+:SrSnO3@APTS exhibited peanut-like morphology, composed of two or more spherical nanoparticles with an average diameter ∼33 nm. Effects of environmental pH values and doping concentrations as well as amino functionalization on the structure of Eu3+:SrSnO3 were investigated. The as-synthesized optical nanosensor was used for determination of copper ions based on a fluorescence quenching approach. Red emission with a long lifetime was obtained in the case of the 0.06 mol Eu3+:SrSnO3@APTS sample. Under the optimal experimental conditions, a Stern–Volmer plot exhibited a good linearity for copper ions over the concentration (0.00–10.8) × 10−11 mol L−1 with a correlation efficient of 0.996 and a limit of detection 3.4 × 10−12 mol L−1. The fluorescent sensor was dynamically quenched via a coulombic interaction mechanism between the Eu3+ (5L6) and Cu2+. The Eu3+:SrSnO3@APTS nanosensor with the optimal Eu3+ dopant concentration of 0.06 mol was applied for copper determination in food and real drink water samples with high recovery values. We believe that the developed nanosensor probe can also be used for the detection of other toxic compounds, with high selectivity and sensitivity.

Morphological control of t-REPO4 (RE = Ho-Lu and Y) via solvothermal reaction and investigation of down-/up-conversion photoluminescence

Doughnut-shaped t-LuPO4 microparticles (∼1.3−1.5 μm in diameter and 1.1–1.3 μm thick) were originally synthesized via lactic acid (LA) assisted solvothermal reaction, and the effects of LA content and PO43−/Lu3+ molar ratio on phase/morphology evolution were thoroughly investigated. It was demonstrated that LA significantly altered the intrinsic crystallization habit of t-LuPO4 and simultaneously promoted 2D growth and 3D self-assembly of the crystallites. The synthesis strategy was also shown to be well extendable to the other t-REPO4 of RE = Ho-Yb and Y. With t-LuPO4 as a representative host, the down-conversion photoluminescence properties (excitation/emission, florescence decay, quantum efficiency) of Sm3+, Dy3+, Tb3+, Eu3+ and Tb3+/Eu3+ pair were thoroughly investigated. For the series of t-(Lu0.98-xTb0.02Eux)PO4 (x = 0−0.12) ternary phosphors, color-tunable emission (from green to red) was obtained through Tb3+ → Eu3+ energy transfer, and the optimal Eu3+ content was determined to be x = 0.08 for the total luminescence of Eu3+ and Tb3+. Under 978 nm laser excitation, t-(Lu0.88Yb0.10Er0.02)PO4 phosphor was found to exhibit strong green (522/547 nm; 2H11/2/4S3/2 → 4I15/2) and red (655/665 nm; 4F9/2 → 4I15/2) up-conversion luminescence via a two-photon process. The merits of the morphology control of this work were also clearly demonstrated by comparing the luminescence performances of Eu3+ in microdoughnut particles and nanoparticles synthesized without LA.