Enhancement of magnetism of Zn0.95Co0.05O films by p-type Cu+ doping

Organic solar cells withμ-oxo-bridged gallium phthalocyanine dimer(GaPc dimer) and fullerene were produced by an evaporation method.A device based on the GaPc dimer provided a conversion efficiency of 4.2×10~(-3)%,which is better compared to a device based on phthalocyanine monomer.Dimerization effect was discussed with a molecular orbital calculation,and the crystalline phases of the present solar cells were investigated by X-ray diffraction.Further improvement of the efficiency was discussed on the bas...     

Chemical states of the atoms in magnetic multilayers Ta/NiO x /Ni81Fe19/Ta and Co/AlO x /Co

Ta/NiO _x /Ni₈₁Fe₁₉/Ta and Co/AlO _x /Co multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field (H _ex) and the coercivity (H _c) of NiO _x /Ni₈₁Fe₁₉ as a function of the ratio of Ar to O₂ during the deposition process were studied. The composition and chemical states at the interface region of NiO _x /NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that when the ratio of Ar to O₂ is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is +2. At this point, NiO _x is antiferromagnetic NiO and the corresponding H_ex is the largest. As the ratio of Ar/O₂ deviates from 7, the H _ex will decrease due to the presence of magnetic impurities such as Ni⁺³ or metallic Ni at the interface region of NiO _x /NiFe, while the H _c will increase due to the metallic Ni. Al layers in Co/AlO _x /Co multilayers were also studied by angle-resolved XPS. Our finding is that the bottom Co could be completely covered by depositing an Al layer about 1.8 nm. The thickness of AlO _x was 1.2 nm.     

Enhanced superconducting performance in solution-derived YBCO-BaZrO_3composite film

YBa_2 Cu_3 O_(7-δ)/BaZrO_3(YBCO/BZO) composite film with enhanced flux-pinning performance was prepared on LaAlO_3(LAO) substrate via a fluorine-free sol-gel method in combination with a novel photosensitive sol-gel lithography technique.Owing to the difference of lattice mismatch between the interfaces of YBCO/LAO and YBCO/BZO,high-density stacking faults were successfully introduced into YBCO matrix,which has been confirmed by XRD and HRTEM analysis.Magnetization measurement results indicate that YBCO/BZO composite film has a stronger current-carrying capacity than the pure YBCO film especially under applied magnetic fields.However,the critical current density of YBCO/CeO_2 composite film is much lower than that of the pure YBCO film at all the applied magnetic fields due to the chemical reaction between YBCO and CeO_2.Therefore,it can be concluded that the flux-pinning performance of YBCO film can be improved by the lattice distortions within YBCO matrix as long as the metal oxide microarrays cannot react with YBCO films.     

La0.7Ca0.3Mn1-xCuxO3的电输运特性

通过固相反应法制备不同掺杂浓度的La_0.7Ca_0.3Mn_1-xCu_xO₃（x=0~0.15）样品, 在77~300 K温度范围内测量了铜掺杂后样品电阻随温度的变化关系. 结果表明, 在未引入铜杂质时, 低温铁磁相的电阻率满足T^2.5关系, 顺磁相符合小极化子近邻跳跃模型; 在低掺杂下, 铁磁区可用T^4.5关系解释; 随着掺杂浓度的增加, 在铁磁区和顺磁区, 任何单一模型均与实验不相符, 表明高掺杂样品的电输运性质存在未知模型.      

钴掺杂Mn3O4作为模板制备锂离子电池正极LiMn2O4

以水热合成的钴掺杂Mn₃O₄作为模板,通过固相反应制备尖晶石LiMn₂O₄。XRD谱图和SEM照片显示制备的LiMn₂O₄具有岩石状结构并呈现良好的结晶性,同时Co的引入能够引起LiMn₂O₄晶格的收缩。作为锂离子电池正极材料,Co含量的增加能够提高循环稳定性但降低材料放电比容量,3% Co掺杂的LiMn₂O₄在0.5 C的电流密度下,经过100次循环后,剩余放电比容量达101.6 mAh·g^-1;在10 C的电流密度下,放电比容量可维持在81.0 mAh·g^-1,优于未掺杂的LiMn₂O₄。这是由于Co的引入能够稳定LiMn₂O₄晶体结构并抑制循环中的姜-泰勒扭曲。     

White organic light-emitting devices using Zn（BTZ）2 doped with Rubrene as emitting layer

Zn(BTZ)2 was synthesized from the complex reaction between zinc acetate dihydrate and 2-(2-hydroxyphenyl) benzothiazolate. Then Zn(BTZ)2 was used as main light-emitting material doped with different amounts of fluorescent dye Rubrene and fabricated a series of white organic light emitting devices. The configurations were as follows: ITO/PVK:TPD/Zn(BTZ)2:Rubrene/Al. The doping concentration of Rubrene in Zn(BTZ)2 was 1.2%, 0.12%, 0.08% and 0.05%, respectively. According to the EL spectra and CIE coordinates of the above devices, the optimum doping concentration (0.05%, weight percent) had been determined. The steady and bright white light emitting of the device with 0.05% doping concentration had been obtained, and the white emission covered a wide range of driving voltage (10--22.5 V). The CIE coordinates were (x=0.341, y=0.334) at the driving voltage of 20 V, which was very close to the equi-energy point (x=0.333, y=0.333), and the corresponding luminance and external quantum efficiency were 4048 Cd/m^2 and 0.63% (4.05 Cd/A), respectively. Lastly, we also discussed the emitting mechanisms of the material and the devices.     

Structure and electrochemical properties of LiLaxMn2-xO4 cathode material by the ultrasonic-assisted sol-gel method

Powders of spinel LiLa_xMn_2—xO₄ were successfully synthesized by the ultrasonic-assisted sol-gel (UASG) method. The structure and properties of LiLa_xMn_2—xO₄ were examined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electronic microscopy (SEM), galvanostatic charge-discharge test, and cyclic voltammetry (CV). XRD results show that the La³⁺ can partially replace Mn³⁺ in the spinel and the doped materials with La³⁺ have a larger lattice constant compared with pristine LiMn₂O₄. FT-IR indicates that the absorption peak of Mn³⁺−O and Mn⁴⁺− O bonds has a red and blue shift with the increase of doping lanthanum in LiLa_xMn_2—xO₄, respectively. The charge-discharge test exhibits that the initial discharge capacity of LiLa_xMn_2—xO₄ drops off, and the capacity retention increases gradually at C/5 discharge rate with the increase of doping lanthanum, and LiLa_0.01Mn_1.99O₄ has a higher discharge capacity and a better cycling performance at 1C discharge rate. CV reveals that the doping La³⁺ is beneficial to the reversible extraction and intercalation of Li⁺ ions.     

Transition-metal-doped Fe2O3 nanoparticles for oxygen evolution reaction

Hematite(α-Fe_2O_3)has been extensively studied as a promising photocatalyst,with the capacity to split water under visible light.To tune its electronic structure and improve the performance for oxygen evolution reaction(OER),high-quality single crystals ofα-Fe_2O_3nanoparticles were synthesized and doped by various transition metals(M=V,Cr,Mn,Zn,Co,Ni,Cu,Nb,Mo,Ti)by a molten-salt flux method.Optical,electronic and catalytic properties of transition-metal-dopedα-Fe_2O_3(TM-dopedα-Fe_2O_3)have been systematically investigated.Cobalt has been identified as the best dopant forα-Fe_2O_3,reducing the OER overpotential by 0.16 V with respect to the undoped.     

Co掺杂对Zn1-xCoxO稀磁半导体光学性质的影响

溶胶-凝胶法制备了Co掺杂的ZnO基稀磁半导体,研究其粉体和薄膜的结构和光学特性.X射线衍射结果表明Co2 随机替代Zn2 位置进入ZnO晶格,并引起晶格常数的变化.紫外-可见透射光谱表明样品的禁带宽度随着Co掺杂浓度的增大呈现非单调变化规律,低浓度掺杂样品的光学带隙随掺杂浓度增大而减小(红移),这是由于Co2 替代Zn2 ,局域d电子与能带电子之间的sp-d交换耦合引起的.     

Enhancement of magnetic properties and thermal stability of nanocrystalline (NdDyTb)12.3(FeZrNbCu)81.7B6.0 alloy with Co substitution

The major drawbacks of Nd-Fe-B magnets are relatively low Curie temperature and poor thermal stability. Ribbons with the near stoichiometric 2:14:1 composition of Nd_10.8Dy_0.75Tb_0.75Fe_79.7-xCo_xZr_0.8Nb_0.8Cu_0.4B_6.0 (x=0, 3, 6, 9, 12, 15) were prepared by rapid quenching and subsequent heat treatment. The effect of Co element on the magnetic properties, thermal stability, and microstructure of the ribbons was systematically studied by vibrating sample magnetometer (VSM), thermal magnetic analysis, atomic force microscopy (AFM), and transmission electron microscopy (TEM). It was found that Co substitution was significantly effective in improving the magnetic properties and the thermal stability of nanocrystalline ribbons. Although the intrinsic coercivity decreased from 1308.7 kA/m for x=0 to 817.4 kA/m for x=15, the remanence polarization and maximum energy product increased from 0.839 T and 116.5 kJ/m3 for the Co-free samples to 1.041 T and 155.1 kJ/m3 for the 12at% Co-substituted samples, respectively. About 10 K increase in Curie temperature was observed for the 2:14:1 phase with 1at% Co substitution. The absolute values of temperature coefficients of induction and coercivity were significantly decreased with Co substitution, which may be attractive for high operational temperature applications. The microstructure of nanocrystalline ribbons was slightly refined with Co substitution.     

Structural and dielectric study of nano-crystalline single phase Sn1−xNixS (xNi=0–10%) showing room temperature ferromagnetism

SnS is a promising Ⅳ-Ⅵ semiconductor,which is very less explored for diluted magnetic semiconducting and dielectric applications.In this study,the Ni doping(x_(Ni)=0-10mol%) effects on SnS host lattice were investigated.A simple and low cost co-precipitation technique was employed to grow Ni doped SnS powders.The X-ray diffraction confirmed single phase orthorhombic structure with a nano-crystalline nature that was further verified through the surface structure observed by scanning electron microscopy.Near edge x-ray absorption fine structure spectroscopy revealed a shift in the Ni absorption edge towards higher energy,depicting the formation of Ni~(+3) oxidation state.The impedance measurements,in the frequency range 1 kHz to 20 MHz,depict that owing to the excellent sensitivity to the electromagnetic radiations at the low energy,the Ni doped SnS finds potential applications in various energy related devices.Vibrating sample magnetometer measurements have elucidated room temperature ferromagnetism,which depicts potential memory device applications.     

Harmonic frequency mixing using highT c superconductor Josephson junction mounted on pulse tube cryocooler

A frequency mixing system including microwave coupling and intermediate frequency (IF) measurement arrangements is designed. In lieu of liquid nitrogen, a pulse tube cryocooler is used to cool the whole system. With YBa₂Cu₃O₇/Yttrium stabilized zirconia (YBCO/YSZ) bicrystal Josephson junction as the mixing element, 36th harmonic frequency mixing at the 8 mm waveband is obtained.     

Induced modi fi cations in the properties of Sr doped BiFeO3 multiferr oics

Multiferroics exhibit unique combination of ferroic properties,simultaneously.For instance,in BiFeO3,magnetic and electric properties co-exist.In this work,BiFeO3 and Sr-doped BiFeO3 samples with general formula,Bi1-x Srx FeO3(x=0.00,0.05,0.10,0.20,and 0.30) were synthesized by sol-gel auto-combustion technique,in order to investigate these ferroic properties.The samples were confrmed to have perovskite type rhombohedral structure,characteristic of BiFeO3.A dilute phase of Bi2Fe4O9was also found in all the Sr-doped samples.The micrographs of the palletized samples revealed that minutely doped Sr might not have any effect on the morphology of the samples.Frequency dependent dielectric measurements were carried out at room temperature for all the samples from 100 Hz to 1 MHz.The dielectric constant of un-doped sample at low frequency was 52 which decreased with increasing Sr doping.An enhancement of magnetic properties was observed with increasing the Sr contents.Pure BiFeO3 material was observed to have the least value of remanent magnetization.As the Sr2+ tions were doped in BiFeO3,its magnetization and remanence were increased to 0.867 emu/g and 0.175 emu/g,respectively,at x=0.30.     

Efficient and selective recovery of Ni,Cu, and Co from low-nickel matte via a hydrometallurgical process

Low-nickel matte was intensively characterized, and Ni, Cu, and Co were determined to exist mainly as (Fe,Ni)₉S₈ and FeNi₃, Cu₅FeS₄, and (Fe,Ni)₉S₈ and Fe₃O₄ (in isomorphic form), respectively. The efficient and selective extraction of Ni, Cu, and Co from the low-nickel matte in an (NH₄)₂S₂O₈/NH₃·H₂O solution system was studied. The effects of (NH₄)₂S₂O₈ and NH₃·H₂O concentrations, leaching time, and leaching temperature on the metal extraction efficiency were systematically investigated. During the oxidative ammonia leaching process, the metal extraction efficiencies of Ni 81.07%, Cu 93.81%, and Co 71.74% were obtained under the optimal conditions. The relatively low leaching efficiency of Ni was mainly ascribed to NiFe alloy deactivation in ammonia solution. By introducing an acid pre-leaching process into the oxidative ammonia leaching process, we achieved the high extraction efficiencies of 98.03%, 99.13%, and 85.60% for the valuable metals Ni, Cu, and Co, respectively, from the low-nickel matte.     

Near-infrared to visible up-conversion emissions of Er^3＋ doped Al2O3 powders derived from the sol-gel method

The Er3 doped Al2O3 powders were prepared by the sol-gel method using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of the erbium nitrate [Er(NO3)3.5H2O]. The different phase structure, including three crystalline types of (Al,Er)2O3 phases, γ, θ, α, and two Er-Al-O phases, ErAlO3 and Al10Er6O24, was obtained with the 1 mol% Er3 doped Al2O3 powders at the different sintering temperatures of 600―1200℃. The green and red up-conversion emissions centered at about 523, 545 and 660 nm, corresponding respectively to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3 , were detected by a 978 nm semiconductor laser diodes excitation. The phase structure and OH content had evident influence on the up-conversion emissions intensity. The maximum intensities of both the green and red emissions were obtained respectively for the Er3 doped Al2O3 powders sintered at 1200 ℃, which was composed mainly of α-(Al,Er)2O3, less of ErAlO3 and Al10Er6O24 phases, and with the least OH content. The two-photon absorption up-conversion process was involved in the green and red up-conversion emissions of the Er3 doped Al2O3 powders.     

TFEL of Ce3+ in zine sulpho-oxide

A new TFEL material ZnS_xO_1−x: Ce³⁺ is prepared. The EL brightness of ZnS_xO_1−x: Ce³⁺ is at least one order higher than that of ZnS: Ce³⁺ at the same doping concentration of Ce³⁺. The EL emission wavelength of ZnS_xO_1−x: Ce³⁺ (X = 0.5) ranges from 400 to 600 nm. The emission of ZnS_xO_1−x: Ce³⁺ may be used as the blue part of white TFEL.     

Synthesis and electrochemical properties of LiNi0.8Al0.2−xTixO2 cathode materials by an ultrasonic-assisted co-precipitation method

A new co-precipitation route was proposed to synthesize LiNi_0.8Al_0.2−xTi_xO₂ (x=0.0-0.20) cathode materials for lithium ion batteries, with Ni(NO₃)₂, Al(NO₃)₃, LiOH·H₂O, and TiO₂ as the starting materials. Ultrasonic vibration was used during preparing the precursors, and the precursors were protected by absolute ethanol before calcination in the air. The influences of doped-Ti content, calcination temperature and time, additional Li content, and ultrasonic vibration on the structure and properties of LiNi_0.8Al_0.2−xTi_xO₂ were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge-discharge tests, respectively. The results show that the optimal molar fraction of Ti, calcination temperature and time, and additional molar fraction of Li for LiNi_0.8Al_0.2−xTi_xO₂ cathode materials are 0.1, 700°C, 20 h, and 0.05, respectively. Ti doping facilitates the formation of the α-NaFeO₂ layered structure, and ultrasonic vibration improves the electrochemical performance of LiNi_0.8Al_0.2−xTi_xO₂.     

Preparation and characterization of LiAlxMn2-xO4 for a supercapacitor in aqueous electrolyte

LiAl_xMn_2—xO₄ (0≤x≤0.5) was synthesized by high temperature solid-state reaction. The structure and morphology of LiAl_xMn_2—xO₄ were investigated by X-ray diffraction and scanning electron microscopy (SEM). The results indicate that all samples show spinel phase. The polyhedral particles turn to club-shaped, then change to small spherical, and finally become agglomerates with increasing Al content. The supercapacitive performances of LiAl_xMn_2—xO₄ were studied by means of galvanostatic charge-discharge, cyclic voltammetry, and alternating current (AC) impedance in 2 mol·L⁻¹ (NH₄)₂SO₄ aqueous solution. The results show that LiAl_xMn_2—xO₄ represents rectangular shape performance in the potential range of 0-1 V. The capacity and cycle performance can be improved by doping Al. The composition of x=0.1 has the maximum special capacitance of 160 F·g⁻¹, which is 1.37 times that of LiMn₂O₄ electrode. The capacitance loss of LiAl_xMn_2—xO₄ with x=0.1 is only about 14% after 100 cycles.     

Microstructural characterization of as-cast and homogenized 2D70 aluminum alloy

The microstructure of the as-cast 2D70 aluminum alloy and its evolution during homogenization were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analysis. The results indicate that the microstructure of the as-cast 2D70 aluminum alloy mainly consists of the dendritic network of aluminum solid solution and intermetallic compounds (Al₂CuMg, Al₂Cu, Al₉FeNi, Cu₂FeAl₇, and Al₇Cu₄Ni). After conventional homogenization, Al/Al₂CuMg eutectic phases are dissolved into the matrix, and a small amount of high melting-point eutectic Al/Al₂Cu phases exist in the matrix, resulting in an increase in the starting melting temperature. Under double homogenization, the high melting point Al/Al₂Cu phases are dissolved, and no obvious change is observed for the size and morphology of Al₉FeNi, Cu₂FeAl₇, and Al₇CuaNi compounds.     

Syntheses and lyotropic liquid crystal properties of a series of sandwich-type tungstoarsenates heteropoly compounds with As/W ratio of 4/30

A series of sandwich-type tungstoarsenates heteropoly compounds with As/W ratio of 4/30, Na16[As4W30M4(H2O)2O112]·XH2O (M = Zn,Cu,Co,Ni,Mn and Cd), have been synthesized for the first time and structurally characterized by elemental analysis, IR and 183W NMR spectra. The crystal structure of Na16[As4W30Cu4(H2O)2O112]·63H2O was determined to be a triclinic system, of P1 symmetry, a = 1.2721(3) nm, b = 2.451 6(5) nm, c = 2.6450(5) nm, α= 89.90(3)°,β= 77.32(3)°, γ= 89.96(3)°, 2=2. Using tetrahepty lammonium bromide as a phase transfer reagent, [As4W30Cu4(H2O)2O112]16- was transferred from aqueous solution to organic phase (benzene), and the heteropolyanion lost the coordination water molecules to form the coordination-unsaturated ion. After lactic acid was added to the benzene solution, the coordination-saturation was recovered. By esterification reaction between lactic acid and cholesterin, the latter was attached to the heteropolyanion indirectly. Therefore, a new type of lyotropic liquid crystal was obtained, which was characterized by a polarimicroscope, DSC and variable temperature wide-angle X-ray diffraction.