Preparation and electrochemical properties of Y-doped Li_3V_2(PO_4)_3 cathode materials for lithium batteries

Y-doped Li3V2（PO4）3 cathode materials were prepared by a carbothermal reduction（CTR） process.The properties of the Y-doped Li3V2（PO4）3 were investigated by X-ray diffraction（XRD） and electrochemical measurements.XRD studies showed that the Y-doped Li3V2（PO4）3 had the same monoclinic structure as the undoped Li3V2（PO4）3.The Y-doped Li3V2（PO4）3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram（CV）, and electrochemical impedance spectra（EIS）.The optimal doping content of Y was x=0.03 in Li3V2-xYx（PO4）3 system.The Y-doped Li3V2（PO4）3 samples showed a better cyclic ability.The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Y-doping.The improved electrochemical perormances of the Y-doped Li3V2（PO4）3 cathode materials were attributed to the addition of Y3＋ ion by stabilizing the monoclinic structure.

Preparation and Electrochemical Studies of Y-doped LiVPO_4F Cathode Materials for Lithium-ion Batteries

Y-doped LiVPO4F cathode materials were prepared by a carbothermal reduction（CTR） process. The properties of the Y-doped LiVPOaF samples were investigated by X-ray diffraction （XRD） and electrochemical measurements. XRD studies show that the Y-doped LiVPOaF samples have the same triclinic structure as the undoped LiVPO4F. The Li extraction/insertion performances of Y-doped LiVPO4F samples were investigated through charge/discharge, cyclic voltammogram （CV） , and electrochemical impedance spectra（EIS）. The optimal doping content of Y is x=0.04 in LiYxV1-xPO4F system. The Y-doped LiVPO4F samples show a better cyclic ability. The electrode reaction reversibility is enhanced, and the charge transfer resistance is decreased through the Y-doping. The improved electrochemical performances of the Y-doped LiVF＇OaF cathode materials are atlributed to the addidon of Y^3＋ ion by stabilizing the Iriclinic structure.

Synthesis and Electrochemical Properties of Cr-doped Li_3V_2(PO_4)_3 Cathode Materials for Lithium-ion Batteries

Cr-doped Li3V2（PO4）3 cathode materials Li3V2-xCr（PO4）3 were prepared by a carbothermal reduction（CTR） process. The properties of the Cr-doped Li3V2（PO4）3 were investigated by X-ray diffraction （XRD）, scanning electron microscopic （SEM）, and electrochemical measurements Results show that the Cr-doped Li3V2（PO4）3 has the same monoclinic structure as the undoped Li3V2（PO4）3, and the particle size of Cr-doped Li3V2（PO4）3 is smaller than that of the undoped Li3V2（PO4）3 and the smallest particle size is only about 1 1μm. The Cr-doped Li3V2（PO4）3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram （CV）, and electrochemical impedance spectra（EIS）. The optimal doping content of Cr was that x=0.04 in the Li3V2-xCrx（PO4）3 samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Cr-doping. The improved electrochemical performances of the Cr-doped Li3V2（PO4）3 cathode materials are attributed to the addition of Cr^3＋ ion by stabilizing the monoclinic structure.

Synthesis and characterization of novel cathode material Li_3V_2(PO_4)_3 by carbon-thermal reduction method

Li3V2(PO4)3 cathode material was prepared by a carbon-thermal reduction (CTR) process. V2O5, LiOH-H2O, NH4H2PO4 and C were used as starting materials to synthesize Li3V2(PO4)3 by sintering the mixture at 800℃for 24 h. The property of the Li3V2(PO4)3 sample was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurement. The results show that the Li3V2(PO4)3 sample has the same monoclinic structure as the Li3V2(PO4)3 sample synthesized by hydrogen reduction method. The particle size is about 1.5μm together with homogenous distribution. The initial discharge capacity of Li3V2(PO4)3 powder is 120 mA·h·g-1 at the rate of 0.1C, and the capacity retains 112 mA·h·g-1 after 30 cycles.

Synthesis and electrochemical performances of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 cathode materials

LiNi0.6Co0.2Mn0.2O2 was prepared from LiOH·H2O and MCO3(M=Ni,Co,Mn)by co-precipitation and subsequent heating. XRD,SEM and electrochemical measurements were used to examine the structure,morphology and electrochemical characteristics, respectively.LiNi0.6Co0.2Mn0.2O2 samples show excellent electrochemical performances.The optimum sintering temperature and sintering time are 850℃and 20 h,respectively.The LiNi0.6Co0.2Mn0.2O2 shows the discharge capacity of 148 mA·h/g in the range of 3.0-4.3 V at the first cycle,and the discharge capacity remains 136 mA·h/g after 30 cycles.The carbonate co-precipitation method is suitable for the preparation of LiNi0.6Co0.2Mn0.2O2 cathode materials with good electrochemical performance for lithium ion batteries.

Microstructure and mechanical performances of CGHAZ for oil tank steel during high heat input welding

Microstructure and mechanical performances of the coarse grain heat-affected-zone （CGHAZ） for oil tank steel with different Ti content were investigated through Gleeble-3500, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometer. The results show that the strength and low- temperature toughness of base material are significantly improved for the high titanium content steel, but the impact toughness of CGHAZ is seriously deteriorated after the high heat input welding and declined sharply with the heat input increasing, while the effects of heat input on impact toughness are very weak for the low titanium content steel, impact toughness of which is gradually larger than that of high titanium content steel with the welding heat input increasing because of the granular bainite increasing, TiN particle coarsening, and （Ti, Nb） N composition evolution during the high input welding for high titanium content steel.

Magnetic property and recording performance of chemical deposition CoP thin films

The thickness of CoP thin films prepared by wet chemical deposition is of crucial importance on magnetic property and recording perform-ance. The coercivity of CoP films decreased with increasing film thickness. The coercivity was 45.37 kA m 1 at the thickness of 300 nm, and decreased to 21.65 kA m 1 at 5.7 μm. Recording performance tests indicate that, for drums with the same size, different recorded magnetic pole density have different thickness requirements. For 40 mm diameter magnetic drum, the optimal CoP thickness is 3～10 μm for 256 re-corded magnetic poles, 1～2 μm for 512 recorded magnetic poles, and 500～800 nm for 1024 recorded magnetic poles.

Theoretical prediction and experimental realization of transition metal doped rutiles as diluted magnetic semiconductors

First principle calculations have been performed to study the electron structures and magnetic properties of transition metal doped ruilles in order to predict room temperature diluted magnetic semiconductors. Different doping configurailons have been calculated to find the preferred doping site. The ground state energies of both FM and AFM states have been calculated to study the magnetic coupling between the dopants. The calculation results show the Co doped mutile has a Curie temperature of 1438 K. Co doped mille films have been prepared on Si substrate by magnetron sputtering. X-ray diffraction results show that the deposited film is ruille. Hysteresis loop curves measured by vibration sample magnetization show that the film is ferromagnetic at root temperature.

Effects of post-annealing on crystalline and transport properties of Bi_(2)Te_(3) thin films

A well-established method is highly desirable for growing topological insulator thin films with low carrier density on a wafer-level scale. Here, we present a simple, scalable method based on magnetron sputtering to obtain high-quality Bi_(2) Te_(3) films with the carrier density down to 4.0 × 10^(13) cm^(-2). In contrast to the most-used method of high substrate temperature growth, we firstly sputtered Bi_(2) Te_(3) thin films at room temperature and then applied post-annealing. It enables the growth of highly-oriented Bi_(2) Te_(3) thin films with larger grain size and smoother interface. The results of electrical transport show that it has a lower carrier density as well as a larger coherent length(~ 228 nm, 2 K). Our studies pave the way toward large-scale, cost-effective production of Bi_(2) Te_(3) thin films to be integrated with other materials in wafer-level scale for electronic and spintronic applications.

PMMA with Long-Persistent Phosphors and Its Behavior of Luminescence

A new kind of rare earth material with high efficient long-persistent phosphors, such as SrAl2O4:Eu, Dy, has been developed in recent years. The PMMA with long-persistent phosphors is typical one of applications for the phosphors. In this work, we try to probe into the affection of the manufacture process on the PMMA with long-persistent phosphors, to analyze its performance, and its luminescence behavior, especially to study the self-excitation of the PMMA with long-persistent phosphors.

Determination of Mecruy at Trace Level in Natural Water Samples by Hydride Generation Atomic Absorption Spectrophotometry after Cloud Point Extraction Preconcentration

A method for the determination of trace mercury in water samples by hydride generation atomic absorption spectrophotometry after cloud point extraction was proposed in the present work. The effects of pH, concentration of surfactant, and equilibration time on cloud point extraction were discussed. The enhancement factor of 20 and the detection limit of 0.039 μg/L were obtained for mercury with relative standard deviation of 4.8% （n = 11）.

Upconversion emission enhancement of TiO_2 coated lanthanide-doped Y_2O_3 nanoparticles

To investigate the upconversion emission, this paper synthesizes Tm^3＋ and Yb^3＋ codoped Y2O3 nanoparticles, and then coats them with TiO2 shells for different coating times. The spectral results of TiO2 coated nanoparticles indicate that upconversion emission intensities have respectively been enhanced 3.2, 5.4, and 2.2 times for coating times of 30, 60 and 90 min at an excitation power density of 3.21× 10^2 W. cm^-2, in comparison with the emission intensity of non-coated nanoparticles. Therefore it can be concluded that the intense upconversion emission of Y2O3：Tm^3＋, Yb^3＋ nanoparticles can be achieved by coating the particle surfaces with a shell of specific thickness.

In-situ revealing the degradation mechanisms of Pt film over 1000℃

Degradation of a metallic film under harsh thermal-mechanical-electrical coupling field conditions determines its service temperature and lifetime.In this work,the self-heating degradation behaviors of Pt thin films above 1000℃were studied in situ by TEM at the nanoscale.The Pt films degraded mainly through void nucleation and growth on the Pt-SiN_(x)interface.Voids preferentially formed at the grain boundary and triple junction intersections with the interface.At temperatures above 1040℃,the voids nucleated at both the grain boundaries and inside the Pt grains.A stress simulation of the suspended membrane suggests the existence of local tensile stress in the Pt film,which promotes the nucleation of voids at the Pt-Si Nxinterface.The grain-boundary-dominated mass transportation renders the voids grow preferentially at GBs and triple junctions in a Pt film.Additionally,under the influence of an applied current,the voids that nucleated inside Pt grains grew to a large size and accelerated the degradation of the Pt film.

Nonlinear Optical Properties of Porphyrin Derivatives with Electron-donating or Electron-withdrawing Substituents

To investigate photoelectric properties of meso-extended porphyrin derivatives with electron-donating or elec- tron-withdrawing substituents, a series of functionalized porphyrin materials have been designed and synthesized by Suzuki coupling reaction. The meso-extended structures were fully characterized by IH NMR, IR spectroscopy and mass spectrometry. The photophysical properties of porphyrin derivatives were carefully examined by UV-Visible and fluorescence spectra, and the solvatochromic effect was observed and discussed. In particular, Z-scan technique was employed to characterize the third-order nonlinear optical （NLO） properties of the products such as nonlinear absorption and refraction, the third-order nonlinear refractive indexes （x（3）-value） of these porphyrin derivatives achieved 3.9 × 10-12 esu. In addition, the compounds could be self-assembled into highly organized morphologies through phase-exchange method. All the results indicated that the discotic materials have the potential for optoelec- tronic applications.

In situ atomistic mechanisms of detwinning in nanocrystalline AuAg alloy

Detwinning is an important plastic deformation mechanism that can significantly affect the mechanical properties of twin-structured metals.Although many detwinning mechanisms have been proposed for pure metals,it is unclear whether such a deformation model is valid for nanocrystalline alloys because of the lack of direct evidence.Here,the atomicscale detwinning deformation process of a nanocrystalline AuAg alloy with an average grain size of~15 nm was investigated in situ.The results show that there are three types of detwinning mechanisms in nanocrystalline AuAg alloys.The first type of detwinning results from grain boundary migration.The second type of detwinning occurs through combined layer-by-layer thinning and incoherent twin boundary migration.The last one occurs through incoherent twin boundary migration,which results from the collective motion of partial dislocations in an array.

Investigation on high magnetoresistance Ni_(0.81)Fe_(0.19) films grown on (Ni_(0.81)Fe_(0.19))_(1-x)Cr_(x) underlayers

We have fabricated Ni0.81Fe0.19 films with (Ni0.81Fe0.19)1-xCrx films as underlayers by dc magnetron sputtering, the results show that larger anisotropic magnetoresistance (△R/R) values of Ni0.81Fe0.19 films are observed using the underlayers with Cr concentration of ~36 at.% at an optimum underlayer thickness of ~4.4 nm, the maximum AMR value is 3.35%. The results of atomic force microscope (AFM) and X-ray diffraction (XRD) show that the △R/R enhancement is attributed to the formation of large average grain size and the strong(111) texture in the Ni0.81Fe0.19 films.

Ultra-high strength yet superplasticity in a hetero-grain-sized nanocrystalline Au nanowire

Nanocrystalline metals often display a high strength up to the gigapascal level,yet they suffer from poor plasticity.Previous studies have shown that the development of hetero-sized grains can efficiently overcome the strength-ductility trade-off of nanocrystalline metals.However,whether this strategy can lead to the fabrication of nanocrystalline nanowires exhibiting both high strength and superplasticity is unclear,similar to the atomistic deformation mechanism.In this paper,we show that ultra-small nanocrystalline Au nanowires comprising grains in both the Hall–Petch and inverse Hall–Petch grain-size regions can exhibit extremely high uniform elongation(236%)and high strength(2.34 gigapascals)at room temperature.In situ atomic-scale observations revealed that the plastic deformation underwent two stages.In the first stage,the super-elongation ability originated from the intergrain plasticity of small grains via mechanisms such as grain boundary migration and grain rotation.This intergrain plasticity caused the grains in the heterogeneous-structured nanowires to grow very large.In the second stage,the superelongation ability originated from intragrain plasticity accompanied by the diffusion of surface atoms.Our results show that the hetero-grain-sized nanocrystalline nanowires,comprising grains with sizes both in the strongest Hall–Petch effect region and the inverse Hall–Petch effect region,were simultaneously ultrastrong and ductile.They displayed neither a strength-ductility trade-off nor plastic instability.

Microstructure change in deuterium implanted CLAM steel induced by electron irradiation

As Reduced Activation Ferritic/Martensitic (RAFM) steel is considered the primary candidate for use as a structural material in fusion power reactors,many countries are developing different kinds of RAFM.China is developing new CLAM (China Low Activation Martensitic) steel.The study investigates microstructural changes in CLAM steel implanted with deuterium ions induced by 1250 keV electron irradiation from R.T.to 873 K,and observes both the growth and shrinkage of the defect clusters produced by deuterium ion implantation under the electron irradiation.