Preparation and luminescence properties investigation of Eu3+, Tb3+-doped LaNbO4:RE3+ (RE = Eu,Eu/Tb,Tb)

Journal of Materials Science: Materials in Electronics - In this work, doped and co-doped LaNbO4:RE3+ (RE?=?Eu, Eu/Tb, Tb) single crystals were prepared by a unique hydrothermal method...     

Synthesis and luminescence of BiPO4:Ln3+ (Ln = Ce3+, Tb3+) phosphors

BiPO₄:Ce³⁺ and BiPO₄:(Ce³⁺, Tb³⁺) powders were synthesized by the method of precipitation. The X-ray diffraction patterns show that BiPO₄:Ce³⁺ and BiPO₄:(Ce³⁺, Tb³⁺) samples have pure hexagonal phases. The transmission electron microscopy results show that the synthesized samples are nanoparticles. Ethylene glycol plays an important role in the formation of nanoparticles. The excitation spectrum of BiPO₄:Ce³⁺ sample shows the transition from the ground ² F _5/2 state to the excited 5d states of the Ce³⁺ ions. The emission spectrum exhibits a strong band centered at 352 nm originating from the 5d → 4f transitions of the Ce³⁺ ions. The emission spectrum of the BiPO₄:(Ce³⁺, Tb³⁺) sample contains both a weak emission band of the Ce³⁺ ions and strong green emission bands of the Tb³⁺ ions. The excitation and emission spectra show that there are energy transfers between Ce³⁺ and Tb³⁺ ions in the BiPO₄:(Ce³⁺, Tb³⁺) sample. The energy transfers between Ce³⁺ and Tb³⁺ ions improve the emission efficiency of BiPO₄:(Ce³⁺, Tb³⁺) sample.     

Synthesis and luminescence properties of novel β-Zn3BPO7:Ln (Ln = Ce3+, Eu2+, Eu3+) phosphors

This work first reports the synthesis and luminescence properties of rare earth Ce³⁺, Eu²⁺, Eu³⁺ ions doped β-Zn₃BPO₇ phosphors [β-Zn₃BPO₇:Ln (Ln = Ce³⁺, Eu²⁺, Eu³⁺)]. The phosphors were synthesized by a solid-state reaction at high temperature, and their luminescence properties were investigated by measuring the photoluminescence excitation and emission spectra. The f–d transitions of Ce³⁺ and Eu²⁺ ions in the host lattice are assigned and corroborated, which lead to the broad emission band in ultraviolet (UV) and visible region for Ce³⁺ and Eu²⁺ ions under UV excitation, respectively. Typical reddish orange emission from Eu³⁺ in the host lattice was also observed. The spectroscopic characteristics including Stokes shift, crystal field depression, electron–vibrational interaction, and charge transfer band were investigated and compared with that in other borophosphate phosphors. β-Zn₃BPO₇:Eu²⁺ and β-Zn₃BPO₇:Eu³⁺ phosphors show potential application in solid state lighting region.     

Synthesis,structural and optical studies of sol–gel Gd2O3:Eu3+, Tb3+ films

Eu³⁺ and Tb³⁺ co-doped Gd₂O₃ films were elaborated by sol–gel process and dip-coating technique. The films were synthesized by hydrolysis of gadolinium pentanedionate. A homogeneous and stable sol was obtained by the reaction with acetylacetone. Gd₂O₃:Eu³⁺, Tb³⁺ films were crystallized around 500 °C; at an increase of temperature up to 700 °C, oriented growth of (4 0 0) face was observed. The obtained transparent Gd₂O₃: 2.5 at.% Eu³+, 0.005 at.% Tb³⁺ waveguide films at 700 °C display significant optical properties. Different crystallographic properties can be obtained in Gd₂O₃:Eu³⁺, Tb³⁺ films with varying sintering temperatures.     

Color-tunable luminescence by energy transfer mechanism in RE (RE = Eu2+, Tb3+)–doped Na2SrPO4F phosphors

Journal of Materials Science: Materials in Electronics - In the current research work, Eu2+, Tb3+ singly doped and co-doped Na2SrPO4F phosphors have been synthesized by solid-state reaction method...     

Photoluminescence properties and energy transfer in γ-irradiated Dy3+, Eu3+-codoped fluoroaluminoborate glasses

The photoluminescence (PL) properties of singly doped (Dy³⁺) and codoped (Dy³⁺, Eu³⁺) fluoroaluminoborate glasses, with an emphasis on the white light generation, are studied. The γ-irradiation led to the formation of defects in Dy³⁺-doped glasses and photoreduction of Eu³⁺ to Eu²⁺ in codoped (Dy³⁺, Eu³⁺) glasses. The electron paramagnetic resonance spectra confirm the presence of divalent europium ions and defects in Dy³⁺, Dy³⁺–Eu³⁺-doped glasses. The FTIR spectra mainly establish the compaction of glass network due to γ-irradiation. From the PL spectra, the intensity ratio of Dy³⁺ emission bands yellow to blue (⁴F_9/2–⁶H_13/2/⁴F_9/2–⁶H_15/2) defines the site symmetry, covalency, and feasibility of extracting white light. The existence of an energy transfer (ET) from Dy³⁺ to Eu³⁺ ions are established due to the decrease in intensity of Dy³⁺ peaks with an increase of Eu₂O₃ content. Moreover, the non-exponential nature of decay curves was well fitted with the generalization of Yokota–Tanimoto model for electric dipole-quadrupole (S = 8) interaction that is responsible for ET process from sensitizer (Dy³⁺) to activator (Eu³⁺).     

Sol–gel synthesis of long-lasting phosphors CdSiO3: Mn2+, RE3+ (RE = Tb,Eu, Nd) and luminescence mechanism research

Mn²⁺ and RE³⁺ (RE = Tb, Eu, Nd) co-doped CdSiO₃ orange phosphors were prepared at 1050 °C by a sol–gel method. The phase and crystallinity of the synthesized materials were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The luminescence characteristics were analyzed using photoluminescence (PL) spectra, afterglow decay curves, long-lasting phosphorescence spectra, and thermoluminescence (TL) spectra. Due to the difference in co-doped rare earth ionic radii, it varied greatly in trap density and trap depth caused by the different defects deriving from RE³⁺ ions co-doping into the CdSiO₃: Mn²⁺ host. The afterglow intensity and time for these samples increased as follows: CdSiO₃: Mn²⁺0.2%, Nd³⁺0.8% < CdSiO₃: Mn²⁺0.4%, Tb³⁺0.8% < CdSiO₃: Mn²⁺0.4%, Eu³⁺0.3%. CdSiO₃: Mn²⁺0.4%, Eu³⁺0.3% had the best afterglow properties, which could be due to the proper traps formed by Eu³⁺ ions co-doping into the host. The role of RE³⁺ co-doped into the CdSiO₃: Mn²⁺ matrix and the possible long-lasting phosphorescence process was also discussed in this paper.     

Linear and nonlinear optical properties and luminescence of Dy+3-doped aluminoborate glasses: Judd–Ofelt investigation

The nominal glasses composition ((40-x) % H₃BO₃—30% CaO—30% Al₂O₃—x Dy₂O₃), where x?=?1, 2, 3, 4, 5 and 6) were prepared using the melt quenching technique. The absorption spectra reveal the common normal 13 transition peaks of the Dy₂O₃-doped glasses. The linear and nonlinear optical properties were calculated. The Photoluminescence spectra and the decay lifetime were examined. The Judd–Ofelt parameters trend was Ω₄?>?Ω₂?>?Ω₆. The oscillator strength of the experimental, and calculated electronic dipole absorption transition were estimated. The radiative life-time, the radiative branching ratio, the emission and absorption transition cross section were also calculated. The gain coefficient of the transitions was predicted. All the calculated parameters were compared with the previous work. The results reveal that the current glasses composition is a good candidate as a lasing host material and the glasses are highly efficient composition when using in the optical communication fibers.

     

Structural and magnetic properties of Ce3+doped Mg-Co ferrite prepared by sol–gel method

Journal of Materials Science: Materials in Electronics - Ce3+-doped Mg-Co ferrite powder can be prepared by sol–gel spontaneous combustion method. The chemical formula for...     

Synthesis and luminescence properties of GdAlO3 ： Eu3＋

研究了不同退火机制下GdAlO3∶Eu3＋荧光粉的光谱特性。采用高温固相反应法在空气气氛和还原气氛中分别合成了GdAlO3∶Eu3＋荧光粉,讨论了在烧结过程中产生的色心的光谱性质及其对GdAlO3∶Eu3＋发光强度、激发光谱和O2--Eu3＋电荷迁移带位置的影响。研究了后退火对GdAlO3∶Eu3＋光谱特性的影响,进一步解释了VUV激发下的能量传递机制。根据烧结气氛、烧结温度和后退火对色心以及GdAlO3∶Eu3＋光谱特性的影响,找到了一条能有效消除色心获得高荧光强度的两步反应合成路线。     

Synthesis and luminescence properties of Yb3+–Er3+ co-doped LaOCl nanostructures

LaOCl:Yb³⁺, Er³⁺ nanofibers and hollow nanofibers were prepared by electrospinning combined with a double-crucible chlorination technique using NH₄Cl as chlorinating agent. X-ray powder diffraction analysis indicated that LaOCl:Yb³⁺, Er³⁺ nanostructures were tetragonal with space group P4/nmm. Scanning electron microscope analysis and histograms revealed that diameters of LaOCl:Yb³⁺, Er³⁺ nanofibers and hollow nanofibers, respectively, were 117.87 ± 15.48 and 141.09 ± 17.10 nm under the 95 % confidence level. Up-conversion (UC) emission spectra analysis manifested that LaOCl:Yb³⁺, Er³⁺ nanostructures exhibited strong green and red UC emission centering at 526, 548, and 671 nm, respectively, attributed to ²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2, and ⁴F_9/2 → ⁴I_l5/2 transitions of Er³⁺ ions under the excitation of a 980-nm diode laser. It was found that the relative intensities of green and red emissions vary obviously with the addition of Yb³⁺ ions, and the optimized molar ratio of Yb³⁺ to Er³⁺ was 10:1 in the as-prepared nanofibers. Moreover, the near-infrared characteristic emissions of LaOCl:Yb³⁺, Er³⁺ nanostructures were achieved under the excitation of a 532-nm laser. CIE analysis demonstrated that color-tuned luminescence can be obtained by changing doping concentration of Yb³⁺ (and/or Er³⁺) ions and morphologies of nanomaterials, which could be applied in the fields of optical telecommunication and optoelectronic devices. The UC luminescent mechanism and the formation mechanisms of LaOCl:Yb³⁺, Er³⁺ nanofibers and hollow nanofibers were also proposed.     

Eu3+,Ce4+掺杂NaAlSiO4的制备及发光性能

采用高温固相法在1100℃下合成了Eu~(3+)掺杂NaAlSiO_4和Eu~(3+),Ce~(4+)掺杂NaAlSiO_4发光材料,利用粉晶X射线衍射和荧光光谱仪对合成样品进行了物相表征和发光强度的研究。结果表明,在1100℃,NaAlSiO_4的特征峰最明显,Eu~(3+)掺杂浓度为1.8%时,其发光强度最强。在此基础上,又进行了Ce~(4+)掺杂,并制得NaAlSiO_4∶x%Eu~(3+),y%Ce~(4+)样品。该样品在紫外光激发下同时发射红光和蓝光,其发射峰强度随x∶y掺杂比改变而变化,当y∶x≤0.092时,红光强度高于蓝光强度;当y∶x0.092时,蓝光强度高于红光强度,从而可以改变样品的发光颜色。     

稀土发光离子(Er3+,Dy3+,Eu3+)掺杂Ce0.8 Gd0.2 O1.9光学性能的研究

通过甘氨酸-硝酸燃烧法双掺杂制备Ce_(0.8)Gd_(0.95)M_(0.05)O_(1.9)(M=Er~(3+),Dy~(3+),Eu~(3+))(CGMO)固体电解质。利用紫外可见分光光度计和分子荧光光度仪对3种掺杂不同稀土离子在不同烧结温度下得到的CGMO进行光学性能测试,并监测不同烧结温度下CGMO晶界的变化规律。测试结果表明,CGMO均在1673K时结晶程度最好,光子和电子传导能力最优。对比SEM形貌,Ce_(0.8)Gd_(0.95)Dy_(0.05)O_(1.9)电解质具有灵敏度高且可行性强的优势,对于改善GDC烧结条件有一定的指导意义。     

Synthesis and luminescence properties of highly uniform SiO2@LaPO4:Eu3+ core–shell phosphors

SiO₂@LaPO₄:Eu³⁺ core–shell phosphors have been successfully synthesized by a one-step and economical wet-chemical route at low temperature. The as-obtained products were characterized by means of photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The SEM, EDS and XPS analysis indicate that SiO₂@LaPO₄:Eu³⁺ core–shell phosphors can only be synthesized in a pH range of 8–11 and the possible mechanism has been proposed. The XRD results demonstrate that the structure of LaPO₄:Eu³⁺ layers is transferred into monoclinic phase from hexagonal phase after annealing at 800 °C for 2 h. The SiO₂@LaPO₄:Eu³⁺ phosphors show strong orange–red luminescence under ultraviolet excitation. The relative emission intensity of Eu³⁺ increases with increasing the annealing temperature and the number of coating cycles, and the optimum concentration for Eu³⁺ was determined to be 5 mol% of La³⁺ in SiO₂@LaPO₄ phosphors.     

Preparation and luminescence properties of ormosil hybrid materials doped with Tb(Tfacac)3phen complex via a sol–gel process

In this paper, silica-based transparent organic–inorganic hybrid materials were prepared via the sol–gel process. Tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) were used as the inorganic and organic precursors, respectively. The terbium complex, Tb(Tfacac)₃phen (Tfacac=1,1,1-trifluoroacetylacetone, phen=1, 10-phenanthroline) was successfully doped into organically modified silicate (ormosil) matrix derived from TEOS and GPTMS, and the luminescent properties of the resultant ormosil composite phosphors [ormosil/Tb(Tfacac)₃phen] were investigated compared with those of the Tb(Tfacac)₃phen incorporated into SiO₂ derived from TEOS (labeled as silica/Tb(Tfacac)₃phen). Both kinds of the materials show the characteristic green emission of Tb³⁺ ion. The luminescence behavior of the resultant composite products was dependent on the matrix composition. The optimized lanthanide complex concentration in the ormosil/Tb(Tfacac)₃phen was increased compared with in silica/Tb(Tfacac)₃phen. Furthermore, the lifetime of Tb³⁺ in Tb(Tfacac)₃phen, silica/Tb(Tfacac)₃phen and ormosil/Tb(Tfacac)₃phen follows the sequence: ormosil/Tb(Tfacac)₃phen>silica/Tb(Tfacac)₃phen>pure Tb(Tfacac)₃phen.     

SrAl2O4:Eu2+,Dy3+光致发光搪瓷涂层的制备

稀土Eu^2 激活的铝酸盐发光材料是近年来新发展起来的新型长余辉光致发光材料，由于其发光亮度和发光余辉比传统的硫化物高许多，且无毒，无放射性，因而引起广泛关注，采用高温固相反应法制备了SrAl2O4:Eu^2 ,Dy^3 发光材料，并利用SrAl2O4:Eu^2 ,Dy^3 发光材料，参考普通搪瓷的制备工艺，制得了性能稳定的光致发光搪瓷涂层，余辉时间长达12h以上，这种发光搪瓷涂层可用于制造广告牌，交通标牌和建筑物标识牌等，在许多领域有应用前景。     

Luminescence properties and tunable emission of Ca3MgSi2O8:Eu3+, Bi3+ phosphor with Bi3+ → Eu3+ energy transfer

Journal of Materials Science: Materials in Electronics - In this work, Ca3MgSi2O8:Bi3+, Ca3MgSi2O8:xEu3+ (x?=?0, 2, 4, 6, 8, and 10&nbsp;mol%), and Ca3MgSi2O8:6%Eu3+, yBi3+...