Title Phosphor Research Articles

Highly thermal-sensitive robust LaTiSbO6:Mn4+ with a single-band emission and its topological architecture for single/dual-mode optical thermometry

Increasingly rigorous temperature detection applied to characterize physico-chemical state has stimulated thriving demands for contactless optical thermometry, which must overcome obstacles of complex preparation, low sensitivity, poor stability and inflexible design. Herein, a new optical thermal-sensitive LaTiSbO6:Mn4+ and its upgraded engineering frameworks are firstly constructed and systematically analyzed. The title phosphor exhibits specific single-band narrow emission (FWHM = ~31 nm) in deep-red region centered at 683 nm and superior thermal-sensitivity (SR = 2.75% K−1, 298–418 K) based on reliable fluorescence lifetime mode. Outstanding robustness of the phosphor concluded from aging experiment highlights the prerequisites of its practical duration and functional independence in diversified architecture. Through phosphor-in-glass (PiG) strategy, robust products are controllably organized without ascertainable interfacial reaction between introduced particles and glass matrix, yielding intriguing improved performance (SR = 3.01% K−1) inherited from LaTiSbO6:Mn4+. Moreover, fabricated heterogeneous PiG architecture, spatially confining LaTiSbO6:Mn4+ and YAG:Ce3+ to block unfavorable energy-transfer depletion, facilely accomplish dual-mode thermometry without significant mutual interference, integrating the Mn4+-lifetime and highly recyclable fluorescence intensity ratio (FIR) from the Ce–Mn non-thermally-coupled system. This work not only suggests LaTiSbO6:Mn4+ as a promising candidate, but also expands new horizons with the topological composite pathway toward rational designing and perfecting multi-mode thermometer or other versatile constructions.

Identification of dual luminescence centers from a single site in a novel blue-pumped Ca3Sc2Ge3O12:Ce3+ phosphor.

The luminescence spectra of some trivalent rare-earth ions in a garnet host present interesting multisite structures; however, their mechanism is still not fully understood. In this study, for the first time, we directly observed two luminescence centers of Ce3+ at a single site in a novel garnet Ca3Sc2Ge3O12 phosphor. The spectral characteristics of the two luminescence centers were clearly identified using site-selective and time-resolved spectroscopy. Luminescence excitation was observed at 425 nm and 450 nm, corresponding to emissions at 490 (Ce(i)) nm and 530 (Ce(ii)) nm. The decay curves confirmed the existence of energy transfer from Ce(i) to Ce(ii). The potential mechanisms of the multisite luminescence are also discussed. This study gives a new insight into the concentration-dependent red-shift and inhomogeneous broadening of the Ce3+ emission band in the garnet phosphor. The title phosphor showed excellent thermal stability, with more than 90% of the initial intensity at the functioning temperature (323 K). Finally, a white LED lamp was fabricated, which exhibited an excellent color rendering index (82.3) and a proper correlated color temperature (3582 K). These results demonstrate that Ca3Sc2Ge3O12:Ce3+ is highly promising to serve as a blue-pumped phosphor for white LEDs.

Anomalous red luminescence of Sm3+ ions in Sm3+:LaKNaTaO5 single crystals

For the first time much more intense 4G5/2 → 6H9/2 transition than others 4G5/2→6HJ/2 transitions of the Sm3+-doped oxides have been observed.The Sm3+–doped LaKNaTaO5 single crystals have been grown by the flux growth method. The emission and excitation spectra as well as decay profiles of the 4G5/2 luminescent level of the Sm3+ ion have been measured. The decay curve has been fitted by the Inokuti-Hirayama energy transfer model which revealed that electric dipole-dipole interaction is responsible for the energy transfer processes in the Sm3+:LaKNaTaO5 single crystals. The title phosphors may be potentially used as red phosphor for white light-emitting diodes.

Photoluminescence properties of a Ce3+ doped Sr3MgSi2O8 phosphor with good thermal stability.

This study mainly reports an investigation about the crystal structure and photoluminescence properties of a Ce3+ doped alkaline earth metal silicate Sr3MgSi2O8. X-ray powder diffraction (XRD) and structure refinement methods are adopted to characterize the phase composition and crystal structure. The excitation/emission spectra and diffuse reflection spectra (DRS) of the title phosphor are measured and the mechanism of concentration quenching as well as thermal quenching are discussed in detail. Results show that the concentration quenching in Sr3MgSi2O8 is due to dipole–dipole interaction energy transfer between Ce3+ ions. The title phosphor has an excellent thermal stability with 90% emission intensity reserve when the temperature rises to 150 °C. The related mechanism is considered to be the thermal ionization effect and an energy level diagram was proposed to show the thermal ionization process.

Crystal structure and color point tuning of β-Sr1.98-yMgySiO4-1.5xNx: 0.02Eu2+: A single-phase white light-emitting phosphor

A series of β-Sr1.98-yMgySiO4-1.5xNx: 0.02Eu2+ (x = 0, 0.3, 0.6, 0.9, 1.2 and 4/3, 0 ≤ y ≤ 0.5, β-S(M)SON: Eu2+) phosphors were synthesized by a conventional solid state reaction method. The coordination environments of Eu2+ are modified effectively via the introduction of N3- and Mg2+ using different concentration, which is confirmed by XRD refinement results and PL spectra. Both fourier transform infrared (FT-IR) spectra and energy dispersive spectroscopy (EDS) analysis qualitatively confirm that the existence of N3-. The crystal structures of β-Sr2SiO4-1.5xNx (β-SSON): Eu2+ and β-Sr2-yMgySi(O,N)4: Eu2+ (β-SMSON, x = 4/3, y = 0.1) have been determined effectively. Rietveld refinement indicates that N3- dopants most likely partly substitute O22− site. With the increase of N content, the unit cell volume and partial SiO and SrN bond lengths gradually decrease, which are coincided each other. With the introduction of N3-, the emission of Eu(I) (∼465 nm) hardly change but that of Eu(II) (∼540 nm) splits into two emission bands as Eu(II) (∼540 nm) and Eu(II)′ (∼616 nm). According to the analysis of XRD data, unit cell volume, FT-IR spectra, photoluminescence (PL) and reflectance spectra of β-SMSON: Eu2+, it can be concluded that the incorporation of Mg2+ into the host leads to interstitial sites rather than substitutional ones. Mg2+ doping couldn't change the dominant peak wavelengths (DPWs) of Eu(I), Eu(II) and Eu(II)′ sites but only affects the PL intensity of title phosphors and could offset the nitridation effects. The concentration quenching mechanism and thermal activation energy of β-SSON: Eu2+ phosphors are determined effectively. The β-S(M)SON: 0.02Eu2+ phosphor have the feature that it can achieve color-tunable white light-emitting combined with blue light emitting diodes (LEDs) with single activator doped and single-phase host, which enables these materials to be enormous possibilities used in white light emitting diodes.

ChemInform Abstract: Discovery of a Red‐Emitting Li3RbGe8O18:Mn4+ Phosphor in the Alkali‐Germanate System: Structural Determination and Electronic Calculations.

AbstractA solid‐state combinatorial chemistry approach in the M—Ge—O (M: Li, K, Rb) system doped with Mn4+ results in the title phosphor (initial Mn levels of 0.005 M) which is prepared by firing the alkali carbonates, GeO2, and MnCO3 in air (multiple sample container, 800 °C, 4 h).

ChemInform Abstract: Synthesis and Photoluminescence Properties of Ca2Ga2SiO7:Eu3+ Red Phosphors with an Intense 5D0→7F4 Transition.

AbstractNew red emitting title phosphors with different Eu3+ contents are prepared by solid state reaction of CaCO3, Ga2O3, SiO2, and Eu2O3 (air, 1350 °C, 24 h).

Synthesis and luminescence properties of MgO: Sm3+ phosphor for white light-emitting diodes

MgO: xSm3+ (0.02 ≤ x ≤ 0.08) red phosphors are prepared by low temperature solution combustion method. The MgO: XSm3+ phosphor characterized by X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FE-SEM), luminescence and decay time measurements. The results of XRD and FE-SEM show that resultant samples are single phase. The vibration properties MgO phosphor was studied by Fourier transform infrared spectroscopy. The luminescence spectra exhibits four emission bands at 566, 603, 651 and 708 nm corresponding to the various transition from 4G5/2 ground state to lower lying levels 6H5/2, 6H7/2, 6H9/2 and 6H11/2 states, with an excitation wavelength at 404 nm. The chromaticity coordinates have been estimated from the emission spectra and the suitability of title phosphor for white light applications. The lifetime corresponding to the 4G5/2 level of the title phosphor has been found to decrease with the increase in Sm3+ ion concentration.

ChemInform Abstract: Resonant Energy Transfer in (Eu3+, Bi3+)‐Codoped CaZrO3 Red‐Emitting Phosphor.

AbstractThe title phosphor is synthesized by solid state reaction of CaCO3, ZrO2, Eu2O3, and Bi2O3 (alumina crucible, 300—1200 °C, 1 h in air).

ChemInform Abstract: Liquid‐Phase Synthesis of Ba2V2O7 Phosphor Powders and Films Using Immiscible Biphasic Organic—Aqueous Systems.

AbstractBoth powders and films of the title phosphor are synthesized using a biphasic organic—aqueous system consisting of an aqueous solution of Ba(OAc)2 and a solution of VO(OEt)3 in xylene (80 °C, 24 h).

ChemInform Abstract: Nonequivalent Substitution and Charge‐Induced Emitter‐Migration Design of Tuning Spectral and Duration Properties of NaCa2GeO4F:Mn2+ Persistent Luminescent Phosphor.

AbstractCodoping of the title phosphor with Li+, Al3+, N3‐, Ga3+, or B3+ leads to red emission color and improves its duration properties.

Facile Atmospheric Pressure Synthesis of High Thermal Stability and Narrow-Band Red-Emitting SrLiAl3N4:Eu(2+) Phosphor for High Color Rendering Index White Light-Emitting Diodes.

Red phosphors (e.g., SrLiAl3N4:Eu(2+)) with high thermal stability and narrow-band properties are urgently explored to meet the next-generation high-power white light-emitting diodes (LEDs). However, to date, synthesis of such phosphors remains an arduous task. Herein, we report, for the first time, a facile method to synthesize SrLiAl3N4:Eu(2+) through Sr3N2, Li3N, Al, and EuN under atmospheric pressure. The as-synthesized narrow-band red-emitting phosphor exhibits excellent thermal stability, including small chromaticity shift and low thermal quenching. Intriguingly, the title phosphor shows an anomalous increase in theoretical lumen equivalent with the increase of temperature as a result of blue shift and band broadening of the emission band, which is crucial for high-power white LEDs. Utilizing the title phosphor, commercial YAG:Ce(3+), and InGaN-based blue LED chip, a proof-of-concept warm white LEDs with a color rendering index (CRI) of 91.1 and R9 = 68 is achieved. Therefore, our results highlight that this method, which is based on atmospheric pressure synthesis, may open a new means to explore narrow-band-emitting nitride phosphor. In addition, the underlying requirements to design Eu(2+)-doped narrow-band-emitting phosphors were also summarized.

ChemInform Abstract: Calcining Temperatures of Sr1‐3xEuxDy2xAl2O4 (x = 0—0.12) Phosphors Prepared Using the Potassium Carbonate Coprecipitation Method.

AbstractThe title phosphors are prepared by the potassium carbonate coprecipitation method followed by calcination.

ChemInform Abstract: HF‐Free Hydrothermal Route for Synthesis of Highly Efficient Narrow‐Band Red Emitting Phosphor K2Si1‐xF6:xMn4+ for Warm White Light‐Emitting Diodes.

AbstractThe title phosphor is synthesized by a new environmentally friendly hydrothermal method from solutions of SiO2, KHF2, and Mn(HPO4)2 (autoclave, 180 °C, 6 h).

ChemInform Abstract: Design, Synthesis and Characterization of Near‐Infrared Long Persistent Phosphors Ca4(PO4)2O:Eu2+,R3+ (R: Lu, La, Gd, Ce, Tm, Y).

AbstractThe title phosphors are prepared by solid state reactions of appropriate mixtures of CaCO3, NH4H2PO4, Ln2O3 (Ln: Eu, Lu, La, Gd, Tm), and CeO2 (alumina crucible, 1573 K, 6 h).

ChemInform Abstract: Synthesis and Photoluminescence Properties of Ba2GeO4:Mn4+ Novel Deep Red‐Emitting Phosphor.

AbstractThe title phosphor is synthesized by solid state reaction of BaCO3, GeO2, and MnCO3 (air; 1.

ChemInform Abstract: Synthesis and Luminescence Properties of NaLa(MoO4)2‐xAGx:Eu3+ (AG: SO42‐, BO33‐) Red Phosphors for White Light Emitting Diodes.

AbstractThe title phosphors are prepared by solid state reactions of (NH4)6Mo7O24, Na2CO3, La2O3, Eu2O3, and (NH4)2SO4 or (NH4)3BO3 (alumina crucibles, 1100 °C, 3 h).

ChemInform Abstract: Wide‐Band Excited LaBMoO6:Eu3+ Red Phosphor for White‐Light‐Emitting Diode.

AbstractThe new title phosphor is synthesized by solid state reaction of H3BO3, (NH4)6Mo7O24, La2O3, and Eu2O3 (900 °C, 4 h in air).

ChemInform Abstract: Persistent Luminescent and Photocatalytic Properties of ZnxGa2O3+x (0.8 ≤ x ≤ 1) Phosphors.

AbstractThe title phosphors (x = 1, 0.95, 0.9, 0.85, 0.8) are prepared by stoichiometric solid state reactions of ZnO and Ga2O3 (corundum crucible, 1300 °C, 5 h).

ChemInform Abstract: Sunlight Activated Long‐Lasting Luminescence from Ba5Si8O21: Eu2+, Dy3+ Phosphor.

AbstractThe new title phosphor is prepared by solid state reaction of a stoichiometric mixture of BaCO3, SiO2, Eu2O3, and Dy2O3 (95% N2/5% H2, 1250 °C, 10 h).