Synthesis and properties of the modification of micro-crystal LiMn2−x Al x O4 cathode material for Li-Ion batteries

The micro-single crystal material spinel LiMn2-xAlxO4 was prepared by a sol-gel procedure and modified by alumina; the electrochemical measurements show that the performances and characteristics of modified LiMn2-xAlxO4 electrode material are better than those of LiMn2O4. Hence, the modified LiMn2-xAlxO4 is a good cathode material for lithium batteries. This can be explained that the size of the modified particle is larger than that of unmodified material, so electrons can be easily transported between the particles.     

Preparation and effect of oxygen annealing on the electrical and magnetic properties of epitaxial (0001) Zn1−x Co x O thin films

Epitaxial (0001)-oriented Zn_1?x Co _x O ( _x = 0.01, 0.05 and 0.1) thin films were grown on c-sapphire substrates by pulsed laser deposition. The XRD analysis, optical transmittance and XPS measurements revealed that the Co²⁺ substituted Zn²⁺ ions were incorporated into the lattice of ZnO in Zn_1?x Co _x O thin films. The electrical properties measurements revealed that the Co concentration had a nonmonotonic influence on the electrical properties of the Zn_1?x Co _x O thin films due to the defects resulted from imperfections induced by Co substitution. The resistivity remarkably increased and the carrier concentration remarkably decreased in Zn_1?x Co _x O thin films after oxygen annealing at 600 ° under 15 Pa O₂ pressure for 60 mins. Room-temperature ferromagnetic was observed and the ferromagnetic Co amount was smaller than the nominal Co concentration for Zn_1?x Co _x O samples before oxygen annealing. After oxygen annealing, the Zn_1?x Co _x O thin films exhibited paramagnetic behavior. It is suggested that the room-temperature ferromagnetic of Zn_1?x Co _x O thin films may attribute to defects or carriers induced mechanism.     

Direct synthesis of Zn1−x Cd x S (0⩽x⩽1) quantum dots in aqueous solution and application in biology

A simple procedure was presented to directly synthesize Zn1-xCdxS (0≤x≤1) quantum dots (QDs) in aqueous solution. QDs’ structures and properties were characterized by TEM (transmission electron microscopy), XRD (X-ray diffraction) and fluorescence microscopy. For those as-synthesized Zn1-xCdxS QDs, when the molar ratio between Zn and Cd changed from 1 to 0, its photoluminescence (PL) emission peak shifted from 430 nm to 675 nm. PL emission quantum efficiency was up to 15%. The experiment results demonstrated that those alloyed QDs showed a good biocompatibility and could be used as labelling materials in cell biology.     

Effect of Zn2+ content on the microstructure and magnetic properties of nanocrystalline Ni1−x Zn x Fe2O4 ferrite by a spraying-coprecipitation method

Nanocrystalline Ni1-xZnxFe2O4 ferrites with 0≤x≤1 were successfully prepared by a spraying-coprecipitation method.The microstructure was investigated by using XRD and TEM.Magnetic properties were measured with vibrating sample magnetometer(VSM) at room temperature.The results show that the grain size of nanocrystalline Ni1-xZnxFe2O4 ferrite calcined at 600 ℃ for 1.5 h is about 30 nm.Lattice parameter and specific saturation magnetization Ms of nanocrystalline Ni1-xZnxFe2O4 ferrite increase with the Zn2+ ions content at room temperature,and maximum Ms is 66.8 A·m2·kg-1 as the Zn2+ ions content is around 0.5,and coercivity Hc of the nanocrystalline Ni1-xZnxFe2O4 ferrite decreases with Zn2+ ions content.     

The microstructure and properties of Ag(Nb0.8Ta0.2)1−x (Mn0.5W0.5) x O3 ceramic system

The microstructure and dielectric properties of Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3(x=0,0.04,0.08,0.12,0.16) ceramic system were investigated.The Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 ceramics were prepared by the traditional solid-state reaction method and were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and Raman spectrometer.The sintering ability and dielectric properties of Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 were found to be improved with the doping of Mn4+ and W6+ ions.The densification temperature of Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 ceramics decreased from 1 080 ℃ to 1 000 ℃ when x increased from 0 to 0.16.Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 ceramic was found to have the best dielectric properties when x=0.08,larger permittivity(■=547) and smaller dielectric loss(tan■=0.00156).     

A fixed point theorem for a class of β-constrictive operators and its application to the integral equation in L~1(0,∞)

0　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎ 1977,Ｆ .Ｓ .ＤｅＢｌａｓｉ[1] ｄｅｆｉｎｅｄｔｈｅｍｅａｓｕｒｅｏｆｗｅａｋｎｏｎｃｏｍｐａｃｔｎｅｓｓｆｏｒａｎｏｎｅｍｐｔｙｂｏｕｎｄｅｄｓｕｂｓｅｔＧｏｆａＢａｎａｃｈｓｐａｃｅＥａｓｆｏｌｌｏｗ :β(Ｇ) =ｉｎｆ {ｒ>0｜ｔｈｅｒｅｅｘｉｓｔｓａｗｅａｋｌｙｃｏｍｐａｃｔｓｅｔＣｓｕｃｈｔｈａｔＧ Ｃ+Ｂｒ}ｗｈｅｒｅＢｒ ={ｘ ∈Ｅ｜‖ｘ‖ ≤ｒ} ,ａｎｄｄｉｓｃｕｓｓｅｄｉｔｓｐｒｏｐｅｒｔｉｅｓｉｎｄｅｔａｉｌ .Ｉｎ 1981,ｂｙｍｅａｎｓｏｆｍｅａｓｕｒｅｓｏ…     

Novel wide band gap alloyed semiconductors, <Emphasis Type="Italic">x</Emphasis>(LiGaO<Subscript>2</Subscript>)<Subscript>1/2</Subscript>-(1−<Emphasis Type="Italic">x</Emphasis>)ZnO,and fabrication of their thin films

Oxide semiconductor alloys of x(LiGaO₂)_1/2-(1−x)ZnO were fabricated by the solid state reaction between β-LiGaO₂ and ZnO and rf-magnetron sputtering. For the solid state reaction, the wurtzite-type single phases were obtained in the composition range of x⩽0.38. The formation range of the alloys was wider than that of the (Mg_1−x Zn _x )O system, because the β-LiGaO₂ possesses a wurtzite-derived structure and approximately the same lattice constants with ZnO. The electrical resistivity and energy band gap of the 0.38(LiGaO₂)_1/2-0.62ZnO alloyed ceramic were 0.45 Ωcm and 3.7 eV, respectively, at room temperature. For the alloying by sputtering, the films consisting of the wurtzite-type single phase were obtained over the entire composition range of x(LiGaO₂)_1/2-(1−x)ZnO. The energy band gap was controllable in the range from 3.3 to 5.6 eV. For the as-deposited film fabricated using the 0.4(LiGaO₂)_1/2-0.6ZnO alloyed ceramic target, the energy band gap was 3.74 eV, and the electrical resistivity, carrier density and the Hall mobility at room temperature were 3.6 Ωcm, 3.4×10¹⁷ cm⁻³ and 5.6 cm² V⁻¹ s⁻¹, respectively.