共查询到20条相似文献,搜索用时 0 毫秒
1.
《Ceramics International》2020,46(13):20664-20671
Trivalent Er3+-doped La2(MoO4)3 upconversion phosphors with intense green emmision were synthesized at 800 °C by the solid-state reaction route, promoting the development of novel optical thermometry. The color emitted from the samples was minorly affected by the excitation power and doping concentration. Yb3+ is a better sensitizer for the La2(MoO4)3: Er3+ phosphor and it can enhance the emission intensity when a certain amount is co-doping in the system. The up-conversion luminescent mechanism was investigated using the pump power-dependent UC emission spectra. Alkali metal doping increased the up-conversion emission intensities drastically, and Li+ ions can enhance the luminous intensity by more than 20 times. The fluorescence intensity ratio of the transition emission 2H11/2-4I15/2 and 4S3/2-4I15/2 was used to study upconversion optical temperature sensing. The sensitivity changes from doping with diverse alkali metal ions and their effects on the optimal temperature range are discussed in detail. Alkali metal ions doping extended the temperature range, indicating that this phosphor is a potential candidate for temperature-sensing probes. 相似文献
2.
Abstract
Powders of Y2O3 co-doped with Yb3+ and Er3+ composed of well-crystallized nanoparticles (30 to 50 nm in diameter) with no adsorbed ligand species on their surface are prepared by polymer complex solution method. These powders exhibit up-conversion emission upon 978-nm excitation with a color that can be tuned from green to red by changing the Yb3+/Er3+ concentration ratio. The mechanism underlying up-conversion color changes is presented along with material structural and optical properties.PACS
42.70.-a, 78.55.Hx, 78.60.-b 相似文献3.
《Ceramics International》2016,42(6):6899-6905
In the present article, optical properties and energy upconversion in Er3+/Yb3+ co-doped BiNbO4 matrix were investigated. The BiNbO4 matrix was prepared using the solid-state reaction method. X-ray diffraction of the matrix shows that the crystal structure is consistent with ICSD code 74338. The grain distribution and the behavior of doping with Er3+ and Yb3+ on the sample surface were obtained by scanning electron microscope. Raman spectral characterization was carried out to examine the behavior of the vibrational modes of the samples. Upconversion emissions in the visible region at 484.5, 522, 541.5 and 670.5 nm in the matrices BiNbO4:Er,Yb and BiNbO4:Er were observed and analyzed as a function of 980 nm laser excitation power and rare-earth doping concentration. The results show that BiNbO4 is a promising host material for efficient upconversion phosphors. 相似文献
4.
5.
《Journal of the European Ceramic Society》2022,42(15):7258-7266
(Ho1/4Er1/4Yb1/4Lu1/4)2SiO5 is synthesized and characterized for the application of a promising multifunctional thermal and environmental barrier coating (TEBC) material. X-ray diffraction and scanning electron microscopy analysis indicate that a X2-type multiple-RE silicate (4RE1/4)2SiO5 is formed with homogeneous distribution of the four rare earth species. Dense bulk sample exhibits excellent phase stability up to 1400 °C. Key properties including Young’s modulus, thermal conductivity and thermal expansion coefficient show interesting composition effects. Specially, (Ho1/4Er1/4Yb1/4Lu1/4)2SiO5 demonstrates higher elastic stiffness, lower thermal conductivity, lower thermal expansion coefficient and good resistances to molten CMAS and water vapor corrosions. These results confirm the strategy of multiple-RE engineering that may provide optimal property of advanced TEBCs. 相似文献
6.
《Ceramics International》2023,49(18):29682-29689
High-quality cubic YSZ crystals were designed with various contents of Er3+, Tm3+ and Yb3+ to produce white light emission, and grown by the optical floating zone method. The up-conversion luminescence spectra of the crystals under 980 nm laser irradiation show three distinct groups of emission peaks at ∼473 nm (blue) generated by the Tm3+ 1G4→3H6 transition, 531 and 547 nm (green) from the Er3+ 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions, and 640 and 662 nm (red) from the Er3+ 4F9/2 → 4I15/2 transition. The optical power curve obtained by plotting the up-conversion luminescence intensity against the laser power shows that the blue emission involves a three-photon process, whilst both the green and red emissions are the results of two-photon processes. Overall white light emission was observed with the crystal prepared with 0.05 mol% Er2O3, 0.5 mol% Tm2O3 and 2.0 mol% Yb2O3, and this crystal is suitable for use in highly efficient white light emission devices. 相似文献
7.
《Journal of the European Ceramic Society》2023,43(14):6461-6472
Single phase (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4 was synthesized, and its thermal properties and CMAS resistance were investigated to explore its potential as an environmental barrier coating (EBC) candidate. The high entropy phosphate (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4 displays a lower thermal conductivity (2.86 W m−1 K−1 at 1250 K) than all the single component xenotime phase rare-earth phosphates. Interaction of (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4 pellets with CMAS at 1300 °C led to the formation of a dense and uniformed Ca8MgRE(PO4)7 reaction layer, which halted the CMAS penetration into the bulk pellet. At 1400 and 1500 °C the (Lu0.2Yb0.2Er0.2Y0.2Gd0.2)PO4-CMAS corrosion showed CMAS penetrating beyond the reaction layer into the bulk pellet via the grain boundaries, and SiO2 precipitates remaining at the pellet surface. The effects of duration, temperature, and compositions on the resistance against CMAS corrosion are discussed within the context of optimizing materials design and performance of high entropy rare-earth phosphates as candidates for advanced EBC applications. 相似文献
8.
《Ceramics International》2022,48(4):5267-5273
Yb3+/Ho3+ codoped and Yb3+/Er3+/Ho3+ tridoped TeO2–BaF2–LaF3–La2O3 (TBLL) fluorotellurite glasses with low OH? absorption (0.026 cm-1), high glass transition temperature (434 °C) and low phonon energy (784 cm-1) were prepared. Their mid-infrared fluorescence properties and related energy transfer (ET) mechanism were studied under 980 nm excitation. A strong emission at 2.85 μm was realized in Yb3+/Ho3+ codoped tellurite glass, which was attributed to the high-efficiency ET from Yb3+ ions to Ho3+, and the ET efficiency was 91.1%. Further introduction of Er3+ ions induced stronger 2.85 μm emission, and the ET efficiency was improved to 96.2%, ascribed to the establishment of more ET channels and Er3+ ions playing the role of ET bridge between Yb3+ and Ho3+ ions. These results indicate that the Yb3+/Er3+/Ho3+ tridoped tellurite glass could be a hopeful gain medium material for the ~3 μm fiber laser. 相似文献
9.
Na Zhou Peiy Qiu Kan Wang Hualin Fu Guo Gao Rong He Daxiang Cui 《Nanoscale research letters》2013,8(1):518
Water-soluble upconversion nanoparticles (UCNPs) were prepared by a one-pot procedure in a two-phase reacting system. Four kinds of surfactants were tested in the synthesis process as capping agent to tune size and morphology of nanocrystals. Nanoparticles (approximately 70 nm) and rods (400 nm and 2.5 μm) were synthesized, respectively. Then, Fourier transform infrared spectroscopy analysis confirmed the successful linking between UCNP surface and surfactant. Ionic liquids (ILs) and surfactants participated in synthesis process together, competing with each other to cap on UCNPs. ILs still led the competition of capping, while surfactants worked as cooperative assistants to develop functional surface. Further characterizations such as high-resolution transmission electron microscopy and X-ray diffraction indicated the changes in crystallization and phase transformation under the influence of surfactants. In addition, the growth mechanism of nanocrystals and upconversion fluorescence luminance was also investigated in detail. At last, the cytotoxicity of UCNPs was evaluated, which highly suggest that these surface-functionalized UCNPs are promising candidates for biomedical engineering. 相似文献
10.
《Ceramics International》2023,49(12):19840-19850
In this work, novel equiatomic high entropy (Dy1/4Ho1/4Tm1/4Yb1/4)2Si2O7 or (4RE1/4)2Si2O7 ceramic pyrosilicate was fabricated through a single solid solution method to use as environmental barrier coating. The SEM analysis of high entropy powders shows the homogenous mixing and XRD proves the formation of single β-phase after milling and sintering. The coefficient of thermal expansion was reported as (2.3–4.8 × 10−6 K−1) from 400 K−1 to 1723 K−1. The ultra-low thermal diffusivity (0.4 mm2 s−1) and thermal conductivity (0.8 W/m°C) were reported at 1500 °C for this novel HE ceramic disilicate. The as fabricated (4RE1/4)2Si2O7 pyrosilicate shows an excellent CMAS resistant for even up to 48 h and negligible amount of Ca is able to penetrate in the substrate. Rare earth disilicate species with intermediate radii such as Tm3+ helps in maintaining phase stability along with passive element Yb3+ of smaller radii which also protect the interface from severe CMAS attack. However, the rare earth species with larger radii such as Dy3+ and Ho3+ actively take part in apatite formation leading to reduced corrosion activity of CMAS melt by changing its composition. This result confirms the application of (4RE1/4)2Si2O7 as a potential candidate to be used as protecting coating material in harsh combustion environments. 相似文献
11.
《Journal of the European Ceramic Society》2023,43(14):6407-6415
High-entropy materials are considered to be born with lattice distortion, which is still lack of comprehensive investigation in rare earth silicates to date. In this paper, we confirmed the existence of lattice distortions in high-entropy rare-earth silicates via experiments and molecular dynamic simulations. The effects of the lattice distortion on the thermophysical properties are elucidated. Simulation results indicate the lattice distortion is present in both cation and anion sublattice, leading to the compressing and stretching of atomic bond as well as fluctuation of atomic bond strength. Accordingly, lattice distortion in the Si and O sublattice is also verified by the Raman spectra. Furthermore, the thermal conductivity of high-entropy rare earth silicates remarkably reduces and exhibits glass-like behavior, which is confirmed by experiments in cooperation with molecular dynamic simulations. Simulation also reveals that the lifetimes and group velocities of vibrational modes are significantly reduced by lattice distortion, which result in the reduction of overall thermal conductivity of high-entropy rare-earth silicates. 相似文献
12.
《Ceramics International》2019,45(11):14404-14410
Ordered-and-oriented TiO2 nanofibers and nanotubes were prepared by magnetic field-assisted electrospinning, and photocatalytic properties of all samples were analyzed under UV–Vis shine. TiO2 nanofibers/nanotubes prepared by magnetic field-assisted electrospinning showed better degradation effect on rhodamine B, reduced the band gap, increased the contact area of organic pollutants with the sample and higher photocatalytic activity than TiO2 nanofibers/nanotubes prepared by classical electrospinning. The product obtained after high temperature annealing was a mixed phase of rutile phase and anatase phase and could be advantageous to the segregate of photogenic electron hole pairs and enhance the high dye absorption capacity; Surface roughness could increase more active sites and accelerate the reaction rate of photocatalytic activity; the addition of magnetic field regulated the morphology of TiO2, and narrowed the band gap to favor photocatalytic performance. The magnetic field-assisted electrospinning study prepared in this paper was an easy-to-use and versatile method for the preparation of ordered TiO2 nanomaterials, which could be easily extended to practical applications or other materials for photocatalysis and water cleavage. 相似文献
13.
D. Valiev O. Khasanov E. Dvilis S. Stepanov E. Polisadova V. Paygin 《Ceramics International》2018,44(17):20768-20773
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 λem =?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. 相似文献
14.
《Ceramics International》2016,42(13):14710-14715
Usually, Er3+ doping concentration effect on the temperature sensing properties of Er3+ containing materials is ignored. In this work, we demonstrated the influence of Er3+ concentration and excitation path on the spectral and temperature sensing properties in Er3+, Yb3+ co-doped NaGdTiO4 system. The NaGdTiO4: Er3+/Yb3+ phosphors were prepared by a high temperature solid state reaction method. Different spectral patterns for down- and up-conversion processes were observed and ascribed to the different excitation and population routes. The concentration quenching behaviors for down- and up-conversion processes were explained via cross relaxations between Er3+ ions. Most importantly, the Er3+ concentration dependent optical temperature sensing performance was observed and experimentally explained as a fact that the optical transition rate of Er3+ in different samples was changed with various Er3+ doping concentration. 相似文献
15.
Junwei Zhao Jian Wu Junfei Xue Qiannan Zhu Weihai Ni 《Israel journal of chemistry》2016,56(4):242-248
Colloidal superparticles (SPs) are nanoparticle (NP) assemblies in the form of colloidal particles. Assembling nanoscopic objects into mesoscopic or macroscopic composite architectures allows for the bottom-up fabrication of functional nanomaterials. In this study, a method for single-step self-assembly synthesis of Au/NaYF4 : Yb,Er SPs was developed using oil-in-water (O/W) microemulsions to simultaneously encapsulate gold nanoparticles (AuNPs) and NaYF4 : Yb,Er upconversion nanoparticles (UCNPs) via evaporation at room temperature. The synthesized Au/NaYF4 : Yb,Er SPs possess good dispersibility and stability. When the number of AuNPs added is increased, the SPs exhibit decreased upconversion luminescence, which can be ascribed to the Förster resonance energy transfer (FRET) from the NaYF4 : Yb,Er UCNPs to the AuNPs. Time-resolved measurements of the green emission further confirm the existence of a new decay route corresponding to the FRET process. Our research provides a facile and versatile strategy for the synthesis of novel multifunctional nanocomposites with tunable upconversion luminescence properties, which can be of great significance in biological applications. 相似文献
16.
《Ceramics International》2023,49(10):14981-14988
Rare earth ions doped ferroelectrics have attracted wide attentions due to their multifunction characteristics with both ferroelectric/piezoelectric properties and intriguing photoluminescence performance, which show great prospects for future multifunctional devices. In this work, a novel rare earth Er3+ ion modified potassium-sodium niobate (KNN) based ceramics were elaborately designed and prepared by the conventional solid-state reaction. The microstructure, phase structure, electric properties and photoluminescence performance of the Er3+ ion modified KNN-based ceramics were systematically investigated. Enhanced piezoelectricity (a considerable d33 of exceeding 300 pC/N and a large d33* up to 500 p.m./V) was realized through optimizing the substitution of BaZrO3 by (Er0.5,Na0.5)ZrO3. Both down-conversion and up-conversion photoluminescence emissions were detected in the optimal composition. The temperature-dependent upconversion emissions of the optimal Er3+ modified ceramic sample in the temperature range of 303–573K were verified to be applicable for non-contact optical temperature sensing with a maximum sensitivity Sa of 0.0028 K-1 and a peak relative sensitivity Sr of 0.96% K−1. Moreover, low-temperature sensing performance with a maximum Sr of 16.7% K−1 in the temperature range of 80–280K was also presented based on the temperature-dependent down-conversion emissions. With both decent electrical properties and intriguing photoluminescence performance, the Er3+-modified KNN-based ferroelectrics exhibit good application potential in the future multifunctional optoelectronic devices. 相似文献
17.
《Ceramics International》2016,42(5):5635-5641
A series of Yb3+ ions sensitized NaY(WO4)2:Er3+ phosphors were synthesized through a solid-sate reaction method. The X-ray diffraction (XRD), upconversion (UC) emission and cathodoluminescence (CL) measurments were applied to characterize the as-prepared samples. Under the excitation of 980 nm light, bright green UC emissions corresponding to (2H11/2,4S3/2)→4I15/2 transitions of Er3+ ions were observed and the UC emission intensities showed an upward trend with increasing the Yb3+ ion concentration, achieving its optimum value at 25 mol%. Furthermore, the temperature sensing behavior based on the thermally coupled levels (2H11/2,4S3/2) of Er3+ ions was analyzed by a fluorescence intensity ratio technique. It was found that the obtained samples can be operated in a wide temperature range of 133–773 K with a maximum sensitivity of approximately 0.0112 K−1 at 515 K. Ultimately, strong CL properties were observed in NaY(WO4)2:0.01Er3+/0.25Yb3+ phosphors and the CL emission intensity increased gradually with the increment of accelerating voltage and filament current. 相似文献
18.
Dongyu Li Weijiang Xu Zhen Huang Xiao Jin Bing Xu Zhenghe Zhang Tingting Zhang Deng Wang Xuping Liu Hao Suo Qinghua Li 《Journal of the American Ceramic Society》2023,106(1):438-447
The effects of site symmetric distortion induced by the phase transition on up-conversion emission and thermal sensing performance of Gd2(MoO4)3:Yb3+/Er3+ (GMO) crystals were elaborately studied by minimizing interference from many factors. Monoclinic GMO showed a much stronger fluorescence intensity and larger fluorescence intensity ratio under the irradiation of 980 nm laser in comparison to the orthorhombic counterpart. These remarkable up-conversion properties stemmed from the low site symmetry with large site symmetric distortion in monoclinic GMO. Moreover, the thermal sensing property of the samples was assessed based on the fluorescence intensity ratio technique, where monoclinic GMO exhibited much higher maximum absolute sensitivity (Sa = 0.0257 K−1 at 510 K) due to the site symmetric distortion, which was further explained by the Judd–Ofelt theory and polarizability of the chemical bond volume model. Results opened an efficient avenue for achieving highly sensitive thermometry in many daily scenarios via finely tailoring the local site symmetry. 相似文献
19.
《Ceramics International》2022,48(18):26400-26407
The high-entropy rare earth zirconate (La1/5Nd1/5Sm1/5Gd1/5Yb1/5)2Zr2O7 porous ceramics ((5RE1/5)2Zr2O7 PCs) were prepared using a foam-gel casting-freeze drying method combined with segmented calcination process. The results of SEM, TEM, and XRD analyses of the (5RE1/5)2Zr2O7 PCs indicated the formation of a defective fluorite crystal structure, with the rare earth elements homogeneously distributed. Meanwhile, the as-prepared (5RE1/5)2Zr2O7 PCs exhibited high porosity, low bulk density, low thermal conductivity, and relatively high compressive strength. Moreover, the high-temperature thermal conductivity of the samples was evaluated, and the results showed that the (5RE1/5)2Zr2O7 PCs maintain a thermal conductivity of 0.150 ± 0.002 W m?1 K?1 even at 1000 °C. The strategy used in this paper can be extended to the synthesis of other high-entropy porous ceramics with high porosity and low thermal conductivity, which is suitable for applications as thermal insulation materials. 相似文献
20.
Changhui Zhao Weizong Lan Huimin Gong Jinglong Bai Rajendran Ramachandran Sheng Liu Fei Wang 《Ceramics International》2018,44(3):2856-2863
Pristine and Pt-decorated copper ferrite nanotubes (Pt-CuFe2O4 NTs, 0.1%, 0.5%, and 1.0%, mole percent) were prepared by a simple electrospinning method. The samples were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Their gas-sensing properties were evaluated by a commercial CGS-4TPs system. Microscopic images showed that all samples consisted of well-defined nanotubes with diameter of 70?100 nm. Gas-sensing measurements revealed that the Pt-CuFe2O4 NTs had an improved acetone-sensing properties compared with pristine CuFe2O4 NTs. In particular, 0.5% Pt-CuFe2O4 NT-based sensor showed a high response (16.5 at 100 ppm), good selectivity, and long-term stability for acetone at 300 °C. In addition, more Pt dopants would have a greater effect on promoting the sensing properties of the CuFe2O4 NTs at high acetone concentrations. A gas-sensing enhancement mechanism of Pt-CuFe2O4 NT-based sensors was proposed, according to the catalytic oxidation process of acetone molecules, which could be due to the kinetic competition between Pt dopants and CuFe2O4 NTs. 相似文献