查找使用阿拉丁产品的科研文献

Strong red upconversion luminescence of NaYF4: Yb3+, Er3+ through Sc3+ ions doping for temperature sensing

Kou Chen,Duan Bin,Shi Lichun,Yang Hongcai,Ni Heng,Wang Haiyuan,Ye Qing,Hu Junshan,Hu Shigang

The Sc 3+ ions doped NaYF 4 : Yb 3+ , Er 3+ upconversion (UC) nanoparticles are synthesized by thermal decomposition method. We successfully obtained the upconversion luminescence (UCL) nanoparticles from green emission to red emission through doping Sc 3+ ions with different concentrations. Based on the XRD, the phase change process of Sc 3+ ions doped NaYF 4 nanocrystalline phase were demonstrated. More importantly, through the analysis of UC spectrum data, the change in the phase of the NaY/ScF 4 : Yb 3+ , Er 3+ nanocrystalline corresponds to the change in its luminous properties. It determines that the change of crystal field will lead to the change of luminescence, and then modulate the luminescence. NaScF 4 : Yb 3+ , Er 3+ UC nanoparticles exhibit strong red light emission. In addition, the temperature-sensitive properties of the optimal doping concentration of Sc 3+ ion were tested. The sensitivity of NaYF 4 : Yb 3+ , Er 3+ nanoparticles doped with Sc 3+ ion reached the maximum value of 0.024 K − 1 at 498 K. The nanocrystalline has great application value in the fields of optical temperature measurement, biomedicine, bioprobes and colorful display.

Influence of extra trace Mn-doping on the properties of Cu2ZnSn(S,Se)4 absorber layer

Guonan Cui,Yanchun Yang,Ruilan Chen,Chengjun Zhu

Cations substitutions are known to make much significant contribution on achieving the high-quality kesterite Cu 2 ZnSn(S,Se) 4 thin films . And the optimal ratios of Mn, Ni and Co substitutions are reported to be ~0.05, belong to the low doping to reduce their defect density , which looks like to some extent the effect of Na doping. In this study, learning the research experience of alkali metal doping, we introduced the extra trace Mn 2+ ion into the precursor solution without affecting the compositions of other elements (i.e. Cu, Zn, and Sn), and the effect of trace addition on properties of the absorber layer was also studied. It was discovered that crystalline, electrical properties, and hole carrier concentration of Cu 2 ZnSn(S,Se) 4 thin films increased with an increase of Mn incorporation, and the best doping ratio of Mn/(Cu + Zn + Sn) was considered to be 0.03. In addition, the effect of extra trace Mn-doping on the film thickness and elemental compositions of Cu 2 ZnSn(S,Se) 4 absorber layer were studied in detail.

Reduced graphene oxide wrapped MOFs-derived cobalt-doped porous carbon polyhedrons as sulfur immobilizers as cathodes for high performance lithium sulfur batteries

Zhaoqiang Li,Caixia Li,Xiaoli Ge,Jingyun Ma,Zhiwei Zhang,Qun Li,Chengxiang Wang,Longwei Yin

Reduced graphene oxide (RGO) wrapped metal-organic frameworks (MOFs) derived cobalt doped porous carbon polyhedrons synthesized via a carbonization process, are for the first time used for sulfur immobilizers (RGO/C–Co-S) as cathodes for high performance lithium-sulfur (Li–S) batteries. The RGO/C–Co–S cathode exhibits greatly improved electrochemical performance, showing excellent specific capacity of 949   mAh g −1 at 300th cycle at a current density 0.3   A   g −1 , displaying enhanced rate capability with specific capacity of 772, 704 and 606   mAh g −1 at current density of 0.5, 1 and 2   A   g −1 , respectively. The synergetic effect of MOFs-derived porous carbon, homogeneously distributed Co nanoparticles and RGO nanosheets simultaneously contributes to the confinement of sulfur species. The presence of abundant mesopores and micropores is conducive to immobilize large amounts of S species. The homogenously inlaid ultrafine Co nanoparticles can further immobilize sulfur by chemical interactions between Co and S/polysulfides. The RGO nanosheets tightly wrapped on carbon hosts act as barrier layers to prevent polysulfides from diffusing out of the matrix, further suppressing shuttle effect. The porous structure and the RGO can effectively alleviate the volume changes resulted from charge–discharge process. This design strategy can be inspiring for MOF-derived materials in energy storage applications .

Fabrication of high-sensitivity Bi0.2-xCexSr0.5La0.3TiO3 (0

A novel Sm2+ doped broadband far-red BaAl2Si3O4N4: Sm2+ phosphor for plant lighting applications

Jiajie Pan,Youjie Hua,Zhanhao Fan,Hongping Ma

Far-red light plays a crucial role in the field of plant lighting. Herein, a novel far-red phosphor BaAl 2 Si 3 O 4 N 4 : Sm 2+ , which can be effectively excited by blue light, was successfully prepared by high-temperature solid-state reaction. The PL spectrum show a broadband emission range from 600 nm to 950 nm (FWHM = 120 nm), which is well matched with the absorption of P FR in plant. In BaAl 2 Si 3 O 4 N 4 : Sm 2+ , the Ba 2+ are coordinated with three N and six O atoms. When the rare earth ion of Sm 2+ was doped into the host lattice , Ba 2+ was partially replaced by Sm 2+ . The low temperature PL spectra at 8–80 K were studied in detail. It was found that the PL spectra at low temperature were composed of some sharp lines and broadband superposition, which corresponding to the 5 D 0 - 7 F J (J = 0–4) energy level transition of Sm 2+ . It is shown that the broadband emission of the phosphor was caused by the broadening of the 4f 5 5 d 1 energy level due to the strong crystal field effect. The thermal stability analysis showed that the luminescence intensity of BaAl 2 Si 3 O 4 N 4 : Sm 2+ at 150 °C still maintains 62.7 % of that at room temperature , showing excellent thermal stability. All results indicate that BaAl 2 Si 3 O 4 N 4 : Sm 2+ phosphor has important potential applications in the field of plant lighting.

Design of LiAlO2 mosaic structure for preparing high nickel-based LiNi0.88Co0.07Al0.05O2 cathode material by simple hydrolysis method

J. LUO,J.X. Liu,F.M. Xiao,L. Huang,W.C. Li,R.H. Tang,Q. Zhou,Y. Wang

In order to restrain the capacity decay of nickel-rich materials for lithium-ion batteries (LIBs) in advanced energy applications, a Ni-rich cathode (LiNi 0.88 Co 0.07 Al 0.05 O 2 , LANCA) with high-rate capability and cycle life was designed and prepared by coating γ-LiAlO 2 and doping Al 3+ on the surface and inside of the secondary particles, respectively. Specifically, the γ-LiAlO 2 -coated and Al 3+ -doped LANCA samples were synthesized by a simple strategy of pre-coating Ni 0.88 Co 0.07 Al 0.05 (OH) 2 , based on aluminum isopropoxide hydrolysis combined with a post-sintering lithiation process. With the γ-LiAlO 2 and Al 3+ , the capacity retention ratio of the cathode is tremendously improved from 61.7 to 83.6% at 1 C rate after 100 cycles. Even at a heavy current density of 10 C for the LANCA cathode, a high reversible capacity of 154.4 mA h g − 1 can be acquired, which amount to the 82.5% capacity retention at 0.2 C. Detailed morphology and structure observation shows that the side reaction at the electrolyte-cathode interface was suppressed, the structural degradation and intergranular cracking were suppressed, while the diffusion of Li + and conductivity were improved. Therefore, this ingenious structural design has certain reference significance for the development and commercialization of high-performance cathode materials for electric power.

Constructing dimensional gradient structure of Na3V2(PO4)3/C@CNTs-WC by wolfram substitution for superior sodium storage

Shiqi Sun,Yanjun Chen,Jun Cheng,Zeyi Tian,Chao Wang,Guangping Wu,Changcheng Liu,Yanzhong Wang,Li Guo

Na 3 V 2 (PO 4 ) 3 (NVP) has gained enormous attentions due to the high capacity and voltage platform. Nevertheless, poor intrinsic electronic conductivities severely restrict the further development. Herein, a feasible strategy to construct unique dimensional gradient structure of the wolfram doped NVP is proposed via a facile sol–gel method. The introduction of W 6+ with the smaller ionic radius parallelized with local V 3+ ions could stabilize the open NASICON structure of NVP and generate vast of beneficial holes to accelerate the electronic transportation. Notably, the wolfram can combine with the superfluous carbon layer and form the new conductive WC phase to further promote the electronic conductivity. Meanwhile, the coated carbon layers and enwrapped CNTs construct an effective conductive framework for accelerated electronic migration. The twining CNTs promote to inhibit the growth of the sintered grains, reducing the particle size to provide shortened pathway for the migration of Na + . Distinctively, the modified Na 2.97 V 2.99 W 0.019 (PO 4 ) 3 /C@CNTs (W0.01-NVP) composite delivers a superior electrochemical performance. Significantly, it can submit a high reversible capability of 112.5 mAh g −1 at 5C with retaining 86% initial capacity over 500 cycles. As for a super high rate of 50C, it reveals an incredible capacity of 92.6 mAh g −1 and remains 84.5 mAh g −1 over 400 cycles, corresponding to a high retention of 91.30%. The superior electrochemical performance is derived from the enhanced crystal structure resulted from wolfram substitution and the beneficial dimensional conductive system consisting of new WC phase, coated carbon layers and enwrapped CNTs.

Electrochemical properties of Li6+yLa3−yBayNbZrO12 lithium garnet oxide solid-state electrolytes with co-doping barium and zirconium

Tianhang Zhang,Timothy D. Christopher,Saifang Huang,Tilo Söhnel,Yan'gai Liu,Peng Cao

In this work, we co-doped barium (Ba) and zirconium (Zr) in a lithium garnet oxide , to improve its electrochemical properties . In the doping range of y = 0–1.0, the Li 6+y La 3−y Ba y NbZrO 12 (LLBNZO) oxides maintain a cubic crystal structure. A secondary phase of BaZrO 3 emerges when y ≥ 0.75. The ionic conductivity of the developed garnet oxides first increases with Ba-doping in the low doping range and then decreases in the high doping range. It reaches the maximum value in Li 6.5 La 2.5 Ba 0.5 NbZrO 12 when y = 0.5. Cyclic voltammetry shows that the garnet oxides have a wide electrochemical voltage window up to 6 V. The constant-current polarization results on the symmetric cells assembled from Li 6.5 La 2.5 Ba 0.5 NbZrO 12 reveal that this garnet oxide is chemically stable against metallic lithium and has stable cycling performance.

Pr3+ doped Y3GaO6 luminescent thermometer for high temperature conditions

Huimin Li,Shan Wang,Ran Pang,Lihong Jiang,Da Li,Su Zhang,Chengyu Li,Hongjie Zhang

Contactless thermometer based on fluorescence intensity ratio shows unparalleled characteristics compared with traditional contact thermometers. However, few materials are suitable for high temperature (above 573 K) measurement. In this work, Pr 3+ was selected as the emitter and Y 3 GaO 6 :xPr 3+ luminescent thermometers were designed. The phase, crystal structure and morphology were identified using X-ray diffraction, Rietveld refinement and scanning electron microscope. The spectra with multiple ranges were temperature sensitive due to the cross-relaxion mechanism that occurs in the luminescence process. The parameters for temperature measurement were determined based on the peak intensity ratio of 506 and 610 nm at different temperatures (from 293 to 823 K). Y 3 GaO 6 :0.01Pr 3+ displays excellent temperature sensitive performance, in which the relative sensitivity values increase along with the temperature in a wide temperature range and reach 4.09 % K −1 . The thermometric visualization in Y 3 GaO 6 :xPr 3+ can be achieved due to the widely varying luminescence colors at different temperatures.

Efficient separation of uranium in solution by ZnFe2O4 doped with TiO2: Adsorption behaviors and mechanism study

Ling Ding,Xiaolin Liu,Shuai Zhang,Jun Liao,Yong Zhang,Lin Zhang

The spinel composite doped with TiO 2 (TiO 2 @ZnFe 2 O 4 ) was prepared via in situ fabrication and template method to extract uranium(VI) from solution. Compared with ZnFe 2 O 4 and TiO 2 /ZnFe 2 O 4 , TiO 2 @ZnFe 2 O 4 showed a high adsorption efficiency (98.3%) and adsorption capacity (716.2 mg g −1 ), which mainly related to the uniform porous structure of TiO 2 @ZnFe 2 O 4 . After five adsorption–desorption cycles, the removal efficiency of TiO 2 @ZnFe 2 O 4 remained above 90%, indicating that TiO 2 @ZnFe 2 O 4 had excellent reusability. Besides, TiO 2 @ZnFe 2 O 4 possessed excellent adsorption selectivity for uranium(VI) in the existence of competitive ions. The Langmuir adsorption model and pseudo-second order model fitted well the adsorption process, which demonstrated that the remove behavior of uranium(VI) on TiO 2 @ZnFe 2 O 4 was a monolayer chemisorption process. The extraction behavior of TiO 2 @ZnFe 2 O 4 for uranium(VI) was mainly attributed to electrostatic attraction, complexation reaction and oxygen vacancy filling. This study not only provides a high efficiency adsorbent (TiO 2 @ZnFe 2 O 4 ) for the extraction of uranium(VI) from solution but also offers a new effective way to enhance the performance of spinel composite.

AgPd nanoparticles supported on zeolitic imidazolate framework derived N-doped porous carbon as an efficient catalyst for formic acid dehydrogenation

Cheng Feng,Yunhui Hao,Li Zhang,Ningzhao Shang,Shutao Gao,Zhi Wang,Chun Wang

Formic acid (FA) has tremendous potential as a safe and convenient source of hydrogen for renewable energy storage, but controlled and efficient dehydrogenation of FA by a robust solid catalyst constitutes a major challenge. In this report, a metal nanoparticle functionalized zeolitic imidazolate framework (ZIF) derived N-decorated nanoporous carbon (NPC) support was fabricated and used as an efficient FA decomposition catalyst for the first time. The resultant AgPd@NPC catalyst exhibited 100% H2 selectivity and high catalytic activity (TOF = 936 h−1) toward the dehydrogenation of formic acid at 353 K. The synergetic interaction between the metal nanoparticles and NPC greatly enhances the catalytic performance of the as-prepared catalyst.

Characterization on crystal structure of CH3NH3PbIxCl3−x perovskite by variable temperature powder X-ray diffraction

Xue Chen,Ning Li,Yuan Li,Ping Che

In this work the CH 3 NH 3 PbI x Cl 3−x perovskite is obtained by applying vacuum-rotary evaporation procedure with a precursor solution of PbCl 2 and CH 3 NH 3 I in dimethylformamide. Thermal gravimetric and differential thermal analysis (TG-DTA) and the variable temperature powder X-ray diffraction ( in situ XRD) are employed to research the effect of thermal treatment on the decomposition and the crystal structure of perovskite . It is found that tetragonal to cubic phase transition in the typical perovskite disappears in mixed perovskite crystals because the stabilizing action of Cl. The excess Cl in the precursor leads to the intermediate structure CH 3 NH 3 PbCl 3 , and then transforms into CH 3 NH 3 PbI 3 with temperature increasing.