Transmission Electron Microscope Study of YBCO/CeO_2/Si Superconducting Multilayer Films

ＴｒａｎｓｍｉｓｉｏｎＥｌｅｃｔｒｏｎＭｉｃｒｏｓｃｏｐｅＳｔｕｄｙｏｆＹＢＣＯ／ＣｅＯ２／ＳｉＳｕｐｅｒｃｏｎｄｕｃｔｉｎｇＭｕｌｔｉｌａｙｅｒＦｉｌｍｓＬｉＨａｏ（李灏），ＬｉｕＡｎｓｈｅｎｇ（刘安生），ＧｕＨｏｎｇｗｅｉ（古宏伟），ＣｈｅｎＬ...     

Synthesis of yttrium and cerium doped ZnO nanoparticles as highly inexpensive and stable photocatalysts for hydrogen evolution

Yttrium and cerium co-doped ZnO nanoparticles were synthesized by combustion route and characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),energy dispersive spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS),UV-visible diffuse reflectance spectroscopy(UV-vis DRS),photoluminescence(PL)and electrochemical impedance spectroscopy(EIS)techniques.The introduction of yttrium ions has efficiently increased the relative percentage of Ce³⁺ions in ZnO.Yttrium and cerium co-doped ZnO shows efficient photo activity for hydrogen evolution(10.61 mmol/((g·h))higher than previously reported optimal value for rare earth codoped ZnO photocatalysts.This remarkably increased hydrogen evolution can be ascribed to the synergy between electronic anchoring effect of Y³⁺/Y²⁺and Ce⁴⁺/Ce³⁺redox couples.This report presents new idea for the synthesis of efficient photocatalyst using economical route and ion anchoring effect.The hydrogen evolution was also tested using Na₂S and Na₂SO₃as electron donors under visible light illumination.The synthesized photocatalysts also exhibit high stability.     

Oxalate-assisted morphological effect of NaYF4:Yb3+,Er3+ on photoelectrochemical performance for dye-sensitized solar cells

In this study. we have employed a facile oxalate-assisted hydrothermal approach to tailor the morphology of β-NaYF_4:Er~(3+),Yb~(3+)(NYFEY) powders through the variation of the molar ratio of oxalate ions(Oxa~(2-)) and rare earth ions(RE~(3+)) in the range of 0.5:1.1:1.2:1, 5:1. and 10:1. The obtained results show that the crystallinity, particle size and upconversion luminescence intensity of the as-synthesized NYFEY particles are gradually decreased as the Oxa~(2-):RE~(3+) molar ratio increases from 0.5:1 to 10:1. For the purpose of photoelectrochemical performance evaluation,the as-synthesized NYFEY particles with different morphologies are incorporated into the nanocrystalline TiO2 films to form the multifunctional nano-and sub-micro meter composite photoanodes of dye-sensitized solar cells(DSSCs). A short-circuit current density(Jsc) of 14.26 mA/cm~2 and power conversion efficiency(PCE) of 7.31% are obtained for DSSCs prepared with hexagonal rod-like NYFEY crystals,evidencing an increase of 29.8% compared with DSSCs prepared with only TiO_2 nanoparticles. The demonstrated synthesis approach for tailoring the morphology and size of NYFEY particles and enhancing the performance of DSSCs can also be applied for other types of solar cells.     

Synthesis of NaYF4:Nd@NaLuF4@SiO2@PS colloids for fluorescence imaging in the second biological window

Nd doped nanoparticles is commonly used as bioimaging agents but presents poor stability. Here, a polymer coating is applied to NaYF4:Nd nanoparticles using a versatile step-by-step coating strategy. The as-synthesized NaYF_4:Nd@NaLuF_4@SiO_2@PS colloids show good stability in various polar solvent and are very stable in water at least for 6 months. These NaYF_4:Nd@NaLuF_4@SiO_2@PS colloids can exhibit strong down converting photoluminescence when excited by 808 nm lasers. Moreover, these NaYF_4:Nd@NaLuF_4@SiO_2@PS colloids accumulate in liver of mice when used as bio-imaging agents. which exhibit strong fluorescence luminescence in NIR Ⅱ window.     

Preparation and luminescent properties of CaF2:Ln3+ (Ln:Er,Er/Yb)/Nafion composite films

In this work, CaF_2:Ln~(3+)(Ln:Er,Er/Yb)/Nafion composite films were prepared using Nafion as modifications and matrices by dripping method. The composite films were characterized by Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD) and scanning electron microscopy(SEM). Composite films are transparent and CaF_2:Ln~(3+)(Ln:Er,Er/Yb) nanoparticles are well dispersed in Nafion films.The thicknesses of CaF_2:Er~(3+)/Nafion and CaF_2:Er~(3+),Yb~(3+)/Nafion composite film are about 77 and 73 μm,respectively. The nanoparticles in composite film possess cubic phase. CaF_2:Er~(3+),Yb~(3+)/Nafion composite film has stronger characteristic emission of Er~(3+) around 1530 nm with full width at half-maximum(FWHM) of 73 nm and longer luminescence lifetimes of 22.04 μs(25.03%) and 100.77 μs(74.97%).     

Synthesis of La2MoO6@MWCNTs composite catalysts as Pt-free counter electrodes for dye-sensitized solar cell

Pt-free counter electrode(CE) composed of La2 MoO_6(La_2 O_3-MoO_3) was successfully synthesized by simple pyrolysis of lanthanum acetate(C_6 H_9 O_6 La·xH_2 O) and hexaammonium heptamolybdate tetrahydrate((NH4)6 Mo_7 O_(24)·4 H_2 O). Furthermore,three proportions composites catalysts of La2 MoO_6@MWCNTs based on La2 MoO_6 and multiwall carbon nanotubes(MWCNTs) were prepared and characterized as Ptfree catalyst for CE in dye-sensitized solar cells(DSSCs). The morphology and structure of La2 MoO_6@MWCNTs composites were determined by scanning electron microscopy, transmission electron microscope and X-ray diffraction. The electrochemical performance of La2 MoO_6@MWCNTs composite catalysts for CEs was determined by photocurrent-voltage measurements, cyclic voltammetry,electrochemical impedance spectroscopy, and Tafel polarization. The power conversion efficiencies of4.68%, 4.87% and 5.06% are obtained for La2 MoO_6:MWCNTs with the mass ratios of 5:1, 3:1 and 1:1 towards the reduction of I_3~-to I~-under the same conditions,respectively,which are superior to those of MWCNTs(3,94%) and La2 MoO_6(1.71%) electrodes. The experimental results reveal that the presence of MWCNTs results in an augmented active catalytic surface area and enhanced charge transfer from CE to the electrolyte.     

Synthesis of Mg-based composite material with in-situ formed LaH3 and its hydrogen storage characteristics

In this work, a Mg-based composite material with in-situ formed LaH₃, Mg₂NiH₄-LiBH₄ + 20 wt% LaH₃, was prepared by ball milling LiBH₄ and hydrogenated LaMg₂Ni and Mg₂Ni powder mixture, followed by heat treatment at 573 K. The onset dehydrogenation temperature of the composite is reduced by 50 K compared with that of Mg₂NiH₄-LiBH₄. The LaH₃-doped composite shows faster kinetics, absorbing 1.43 wt% hydrogen within 100 s at 423 K, which is 6.5 times faster than Mg₂NiH₄-LiBH₄. Moreover, the composite releases 1.24 wt% hydrogen within 500 s at 573 K, 0.69 wt% higher than Mg₂NiH₄-LiBH₄. The activation energy of the composite is reduced by 8.2 and 80 kJ/mol compared with that of Mg₂NiH₄-LiBH₄ and commercial MgH₂, respectively. The improvement in hydrogen storage properties is attributed to the fact that LaH₃ promotes the generation of nano-sized spongy Mg structure, which has good catalytic activity during the subsequent hydrogenation/dehydrogenation process.     

Preparation and Structural Chemistry of a Series of Rare Earth Compounds REPS 4

ＡｌａｒｇｅｎｕｍｂｅｒｏｆｒａｒｅｅａｒｔｈｏｒｔｈｏｔｈｉｏｐｈｏｓｐｈａｔｅｓＲＥＰＳ４（ＲＥ＝Ｐｒ［１］,Ｓｍ［２］,Ｎｄ［３］,Ｙ,Ｇｄ,Ｔｂ,Ｙｂ［４］）ｈａｓｂｅｎｓｈｏｗｎｔｏｃｒｙｓｔａｌｌｉｚｅｉｎｔｈｅｔｅｔｒａｇｏｎａｌｓ...     

Effects of Er3+ doping on structure and thermal properties of (Sm1–xErx)2Zr2O7 ceramics for thermal barrier coating

Rare earth Er³⁺ doped (Sm_1–xEr_x)₂Zr₂O₇ (x = 0.1, 0.2, and 0.3) ceramic samples were synthesized using a solid state reaction method. The microstructure and thermal properties of these ceramics were investigated to evaluate their potential as thermal barrier coating materials. The results show that ceramics are compact with regular-shaped grains of 1–5 μm size. (Sm_1–xEr_x)₂Zr₂O₇ has a pyrochlore structure mainly determined by ionic radius ratio, but the ordering degree decreases with increase of the Er₂O₃ content. There is no phase transformation from 1000 to 1200 °C, and the (Sm_1–xEr_x)₂Zr₂O₇ ceramics exhibit excellent phase stability during thermal treatment at 1200 °C for 100 h and 1400 °C for 50 h. The thermal conductivities of dense (Sm_1–xEr_x)₂Zr₂O₇ ceramics range from 1.52 to 1.59 W/(m·K), which is lower than that of Sm₂Zr₂O₇, and decrease as the Er₂O₃ content increases. Besides, the thermal expansion coefficient of (Sm_1–xEr_x)₂Zr₂O₇ is higher than that of Sm₂Zr₂O₇.     

Dual-enhancement of chromaticity and thermal stability: In-situ synthesis of core–shell γ-Ce2S3@CePO4 configuration

Non-toxic rare earth (RE) composite materials are promising and active in optoelectronic fields, such as pigment. In this work, Na ions doped γ-Ce₂S₃ pigments were synthesized by solid-phase vulcanization and followed by in-situ synthesis to prepare an outer layer of CePO₄ film. The characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), solid state nuclear magnetic resonance (NMR) indicate that Na-doped γ-Ce₂S₃ and CePO₄ uniformly and tightly coated core–shell structure was successfully synthesized. The thermogravimetric analysis (TG) and reflection spectrum (RS) reveal that the CePO₄ coating significantly improves the colorant and thermal stability performance of γ-Ce₂S₃. The excellent color quality of γ-Ce₂S₃@CePO₄ (L1 = 45.16, a1 = 55.94, b1 = 44.53) is achieved and the red color (L1 = 43.82, a1 = 49.79, b1 = 38.04) is still retained even if the sample is heated in air at 400 °C for 30 min.     

Table-like magnetocaloric effect and large refrigerant capacity of composite magnetic refrigerants based on LaFe11.6Si1.4Hy alloys

Composite magnetic refrigerants were prepared by physical mixing LaFe_(11.6)Si_(1.4)H_y alloys with different Curie temperatures(Tc). The phase structures of these LaFe_(11.6)Si_(1.4)H_y alloys were analyzed by X-ray diffraction(XRD) and the magnetocaloric effect(MCE) and refrigerant capacity(RC) of these composite magnetic refrigerants were investigated by experiment and calculation in this paper. The magnetocaloric effect(MCE) and refrigerant capacity(RC) of these composite magnetic refrigerants were investigated by experiment and calculation in this paper. The results indicate the experimental magnetic entropy change(-△S_M)-Tcurve corresponds reasonably with the(-△S_M)-Tcurve calculated by the linear combination of(-△S_M)-T curves of the single material. An optimal mixing ratio can make the composite magnetic refrigerant possess a table-like(-△S_M)-Tcurve which is beneficial to magnetic Ericsson cycle. When three LaFe_(11.6)Si_(1.4)H_y alloys with different T_c are mixed, the full width at half maximum(△T_(FWHM)) of(-△S_M)-T curves is about 48.7 K and the RC is about 177.76 J/kg under a magnetic field change of 2 T. The composite magnetic refrigerants based on LaFe_(11.6)Si_(1.4)H_y alloys can be promising candidates for near room temperature magnetic refrigeration and the work will be helpful to develop novel composite magnetic refrigerants with table-like MCE and large RC.     

Effect of Tb(III) on the unfolding of ciliate Euplotes octocarinatus centrin induced by guanidine hydrochloride

To understand the unfolding of ciliate Euplotes octocarinatus centrin (EoCen), the glycine positioned at 115, the sixth residue of the loop of the protein's third EF-hand, was mutated into tryptophan (Trp). Intrinsic fluorescence and Tb(III) binding properties of wild type EoCen and G115W mutant were monitored by fluorescence spectra in 10 mmol/L Hepes. The emission maximum of EoCen was 306 nm and mutation had no impact on the Tb(III) binding properties. The properties of G115W were investigated by fluorescence, far-UV circular dichroism (CD) spectra and fluorescence decays in the absence or in the presence of 6 mol/L guanidine hydrochloride (GdnHCl). For the increase in polarity of micro-environment around Trp residue, the emission maximum of apoG115W at 343 nm is shifted to 359 nm in 6 mol/L GdnHCl. Also the secondary structure is lost nearly and fluorescence lifetime decreases in 6 mol/L GdnHCl. The unfolding of G115W induced by GdnHCl was assessed by using the model of structural element. The unfolding of proteins is a sequential reaction, namely two-transition, three-state process. The first transition belongs to the unfolding of the C-terminal domain, and the second transition is assigned to the unfolding of the N-terminal domain. The $\Delta 〈\Delta G_{\text{total}}^0\left({\text{H}}_2\text{O}\right)〉$ was used to determine the effect of Tb(III) on the stability of apoprotein. The $〈\Delta G_{\text{total}}^0\left({\text{H}}_2\text{O}\right)〉$ for Tb₂-G115W has a less increase of 0.68 kJ/mol compared with apoG115W, proving Tb(III) situated at C-terminal has negligible impact on the stability of protein. Whereas the $〈\Delta G_{\text{total}}^0\left({\text{H}}_2\text{O}\right)〉$ for Tb₄-G115W has a rise of 1.29 kJ/mol compared with Tb₂-G115W, manifesting Tb(III) located at low affinity sites has considerable influence on protein stability, mainly stabilizing the N-terminal domain.     

Chemical Conversion Film of Mischmetal on Zinc Deposit

ＣｈｅｍｉｃａｌＣｏｎｖｅｒｓｉｏｎＦｉｌｍｏｆＭｉｓｃｈｍｅｔａｌｏｎＺｉｎｃＤｅｐｏｓｉｔＷａｎｇＪｉｋｕｉ（王济奎）（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＣｈｅｍｉｓｔｒｙ，ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙｏｆＣｈｅｍｉｃａｌＴｅｃｈｎｏｌ...     

Synthesis and Properties of Heteropoly Complexes LnHSiW_(12)O_(40)·xH_2O

The present paper covers seven rare earth-containing tungstosilicate heteropoly complexesLnHSiW_(12)O_(40)·xH_2O with Keggin structure(Ln=La,Ce,Pr,Nd,Sm,Eu and Gd)snythesized by doubledecomposition reaction.The synthesized heteropoly complexes were characterized by ICP,~(29)Si-NMR,XPS,XRD,IR,UV,polarogram,CV and TG-DTA.The relationship between the structure of the synthesizedheteropoly complexes and their properties is discussed.