Magnetic and Photocatalytic Behaviors of Ca Mn Co-Doped BiFeO₃Nanofibres

Ca and Mn co-doped BiFeO3 ultrafine nanofibres were prepared with the purpose of improving magnetic and photocatalytic performances of the one-dimensional multiferroic material. Impurity phase introduced by both Bi fluctuation and Mn substitution can be suppressed by Ca doping and a space group transition from R3c to C222 can also be triggered by Bi-site doping. With co-substitution of Mn into iron site, the Ca0.15Bi0.85Mn0.05Fe0.95O3 nanofibres presented a larger saturation magnetization than the singly Ca doping samples, possibly due to the increased double exchange interation of Fe3+-O-Fe2+, strengthened by Ca and Mn. Photocatalytic degradation test witnessed a similar drop-and-rise performance with the magnetism.

Anisotropy of Photocatalytic Properties in Nanostructured Photocatalysts

Energy band engineering and the nature of surface/interface of a semiconductor play a significant role in searching high efficiency photocatalysts. Actually, the active facets, morphology controlling, especially the exposed facets modulation of photocatalysts during preparation are very desirable. In order to achieve high photocatalytic performance, intrinsic mechanism of such anisotropic properties should be fully considered. In this review, we mainly emphasis on the latest research developments of several extensively investigated photocatalysts and their anisotropic photocatalytic properties, as well as the correlation between effective masses anisotropy and photocatalytic properties. It will be helpful to understand the photocatalytic mechanism and promote rational development of photocatalyst for wide applications.

High-temperature Electric Properties of Polycrystalline La-doped CaMnO_3 Ceramics

Polycrystalline La-doped CaMnO3 ceramics have been prepared by a solid-state sintering method. Analysis of microstructure and phase composition indicates that the addition of La can prohibit the further growth of grain, and no impurity phase appears. The results revealed that the La doping can lead to a large change of the activation energy （from 0.2：2 to 0.02 eV）, and thus result in a marked increase in electric conductivity of 2-4 orders of magnitude. The power factor can reach about 1.5×10-4 W.m-1.K-2 in a wide temperature range, which potentially make them attractive for n-type high-temperature thermoelectric materials.

Voltage-controlled Kerr response in Ni/Pb(Zr_(0.52)Ti_(0.48))O_3 heterostructures

Voltage-modified magneto-optical Kerr effect(MOKE) is widely used to describe the converse magnetoelectric(ME) effect in the ferroelectric/ferromagnetic(FE/FM) heterostructures. However, the applied voltage can possibly give rise to electro-optical effect of the FE layer, which would also affect the Kerr signals in the MOKE system. Here, we used an AC voltage to modulate the magnetization in the Ni/Pb(Zr0.52Ti0.48)O3(PZT) heterostructures with different pre-polarization states of the PZT layers to investigate the complexity of the Kerr signals. The results suggested that the voltage control of Kerr signal contained several origins; however, the straininduced ME effect dominated in the ME effect in the heterostructures.

Thermoelectric thin films:Promising strategies and related mechanism on boosting energy conversion performance

Thermoelectrics can be capable of direct and reversible conversion between heat and electricity.Low dimensional thermoelectric materials,especially two dimensional(2D)thin films,have been considered as a breakthrough to decouple the correlations between electronic and thermal transport,contributing to the optimization of thermoelectric performance.During the past few decades,some effective strategies combined with physical concepts like quantum confinement effect,energy filtering effect,band structure tuning and interface engineering are introduced to design high performance thermoelectrics.Having a thorough understanding the underlyingmechanisms is essential to develop thermoelectric materials.Here,our review summarizes the major strategies that can be utilized in thermoelectric thin films,including fabrication of superlattice structure,formation of two-dimensional electron gas(2DEG)system,orientation regulation,strain engineering and magnetic manipulation,from the aspects of deep mechanisms analyses,recent progress and prospects,inspiring significant improvement of thermoelectric properties.

Strain-induced modulation of magnetic anisotropy in Co/BaTiO_3 composite

A uniaxial magnetic anisotropy Co film was grown on a single-crystal Ba Ti O3(BTO) substrate. The strain yielded by the voltage-induced ferroelastic domain switching in the BTO substrate was recorded by atomic force microscope and modulated the magnetism of the Co film. The manipulation of the magnetism of the Co film is experimentally demonstrated by voltage dependence of magnetic hysteresis loops measured via magneto-optic Kerr effect.

Self-biased magnetoelectric effect in(Pb, Zr)TiO_3/metglas laminates by annealing method

FeBSiC metglas 以一个优化条件被退火(350 吗？？

Oxidation Behaviors of C-ZrB_2-SiC Composite at 2100℃ in Air and O_2

The oxidation behaviors of graphite and ZrB2-SiC modified graphite composite were investigated at 2100℃ in1X105 Pa air and 0.2X105 Pa O2. The oxidation tests were conducted in an induction heating furnace. The oxidation of these two materials followed the linear rate law. The determined radius loss rates of graphite and C-ZrB2-Si C at 2100℃ were 2.18X10-2and 1.05X10-2%/s in 1X105 Pa air, and 3.23X10 2 and 2.21X10 2%/s in 0.2X105 Pa O2, respectively. The incorporation of ZrB2 and SiC decreased remarkably the oxidation rate of graphite because the oxide scale formed on the sample surface during oxidation helps in reducing the exposed surface area of the underneath substrate. In two different atmospheres with the same oxygen partial pressure, both graphite and ZrB2-SiC experienced more severe oxidation at 2100℃ in0.2X105 Pa O2than in 1X105 Pa air. The oxidation rate-controlling step for graphite and ZrB2-SiC was proposed to be the inward diffusion of oxygen through the boundary layer and through the pores in the oxide scale, respectively. A model based on diffusion theory was established to discuss the effect of the total gas pressure on their oxidation behaviors.

Mechanical and biocompatible properties of polymer-infiltrated-ceramic-network materials for dental restoration

Dental restorative materials with high mechanical properties and biocompatible performances are promising.In this work,polymer-infiltrated-ceramic-network materials(PICNs)were fabricated via infiltrating polymerizable monomers into porous ceramic networks and incorporated with hydroxyapatite nano-powders.Our results revealed that the flexural strength can be enhanced up to 157.32 MPa,and elastic modulus and Vickers hardness can be achieved up to 19.4 and 1.31 GPa,respectively,which are comparable with the commercial computer-aided design and computer-aided manufacturing(CAD/CAM)blocks.Additionally,the adhesion and spreading of rat bone marrow mesenchymal stem cells(r BMSCs)on the surface of such materials can be improved by adding hydroxyapatite,which results in good biocompatibility.Such PICNs are potential applicants for their application in the dental restoration.

High Temperature Thermoelectric Properties of Dy-doped CaMnO_3 Ceramics

Dy-doped CaMnO3 ceramics have been synthesized by co-precipitation method combined with the solid-state reaction.Phase composition and microstructure analysis indicate that high density and pure CaMnO3 phase can be achieved.The electric conductivity can be enhanced by Dy doping,and result in a slight increase of the thermal conductivity.The highest dimensionless figure of merit ZT of 0.15 has been obtained at 973 K for x = 0.02 sample,which is about 4 times larger than that of the pure CaMnO3,which indicate that CaMnO3can be a promising candidate for n-type thermoelectric material at high temperature.

Strong phonon localization in PbTe with dislocations and large deviation to Matthiessen’s rule

Dislocations can greatly enhance the figure of merit of thermoelectric materials by prominently reducing thermal conductivity.However,the evolution of phonon modes with different energies when they propagate through a single dislocation is unknown.Here we perform non-equilibrium molecular dynamics simulation to study phonon transport in PbTe crystal with dislocations by excluding boundary scattering and strain coupling effect.The frequency-dependent heat flux,phonon mode analysis,and frequency-dependent phonon mean free paths(MFPs)are presented.The thermal conductivity of PbTe with dislocation density on the order of 10^(15)m^(−2) is decreased by 62%.We provide solid evidence of strong localization of phonon modes in dislocation sample.Moreover,by comparing the frequency-dependent phonon MFPs between atomistic modeling and traditional theory,it is found that the conventional theories are inadequate to describe the phonon behavior throughout the full phonon spectrum,and large deviation to the well-known semi-classical Matthiessen’s rule is observed.These results provide insightful guidance for the development of PbTe based thermoelectrics and shed light on new routes for enhancing the performance of existing thermoelectrics by incorporating dislocations.

Stretch-shear mode laminated metglas/Pb(Zr,Ti)O3/metglas composite with an enhanced magnetoelectric effect

Magnetoelectric(ME)composites have recently attracted an ever-increasing interest and provoked a great number of research activities,driven by the potential applications in novel multifunctional devices,such as sensors and transducers[1].Direct ME effect,which describe the appearance of an electric polarization P upon applying a magnetic field H,is usually evaluated by the

The role of strain and polar discontinuity in magnetism in LaMnO_3/SrTiO_3/LaAlO_3(001) heterostructures

Creating novel interfacial effects in quantum-matter-based heterostructures is at the heart of condensed matter physics and materials science[1].Utilizing the subtle interplay among charge,spin,orbit and lattice degrees of freedom,these interfacial effects can spawn tailored functionalities and act as additional building blocks for the future oxide electronics.Among the various interfacial effects,the inevitable strain effect induced by unequal lattice constants and the ubiquitous charge redistribution effect at inter-

Preparation of In_2O_3-Sr_2RuErO_6 Composite Ceramics by the Spark Plasma Sintering and Their Thermoelectric Performance

Inl.9aZn0.03Ge0.0303 and Sr2RuEr06 composite ceramics have been prepared by the spark plasma sintering （SPS） technique. Microstructure studies show that the Sr2RuErO6 phases are randomly dispersed in the In1.94Zn0.03Ge0.03O3 matrix. The results show that the Seebeck coefficient increases with increasing the amount of Sr2RuErO6, while the thermal conductivity of the composite samples is lower than that of the Inl.9aZno.03Ge0.03O3 ceramic. The thermal conductivity of the 7 vol.% Sr2RuErO6 sample can decrease to 2.15 W.m-1.K-1 at 973 K, and the evaluated maximum ZT value is 0.23 for 3 vol.% Sr2RuErO6 samples at 973 K, which makes them promising materials for the thermoelectric devices.

Physicochemical properties of proton-conducting SmNiO3 epitaxial films

Proton conducting SmNiO_(3)(SNO)thin films were grown on(001)LaAlO_(3)substrates for systematically investigating the proton transport properties.X-ray Diffraction and Atomic Force Microscopy studies reveal that the as-grown SNO thin films have good single crystallinity and smooth surface morphology.The electrical conductivity measurements in air indicate a peak at 473 K in the temperature dependence of the resistance of the SNO films,probably due to oxygen loss on heating.A Metal-Insulator-Transition occurs at 373 K for the films after annealing at 873 K in air.In a hydrogen atmosphere(3%H_(2)/97%N_(2)),an anomalous peak in the resistance is found at 685 K on the first heating cycle.Electrochemical Impedance Spectroscopy studies as a function of temperature indicate that the SNO films have a high ionic conductivity(0.030 S/cm at 773 K)in a hydrogen atmosphere.The activation energy for proton conductivity was determined to be 0.23 eV at 473-773 K and 0.37 eV at 773e973 K respectively.These findings demonstrate that SNO thin films have good proton conductivity and are good candidate electrolytes for low temperature proton-conducting Solid Oxide Fuel Cells.

Dielectric and varistor properties of rare-earth-doped ZnO and CaCu_(3)Ti_(4)O_(12) composite ceramics

To investigate the multi-functional ceramics with both high permitivity and large nonlinear cofficient,we have prepared rare-earth Tb-and-Co doped ZnO and TO_(2)rich CaCu_(3)Ti_(4)O_(12)(TCCTO)powders by chemical co-precipitation and sol-gel methods re-spectively,and then obtained the TCCTO/ZnO composite ceramics,sintered at 1100℃for 3h in air.Analyzing the composite ceramics of the microstructure and phase composition indicated that the composite ceramics were composed of the main phases of ZnO and CaCu_(3)Ti_(4)O_(12)(CCTO).Our results revealed that the TCCTO/ZnO composite ceramics showed both high dielectric and good nonlinear electrical behaviors.The composite ceramic of TCCTO:ZnO=0.3 exhibited a high dielectric constant of~210(1 kHz)with a nonlinear cofficient of~11.The dielectric behavior of TCCTO/ZnO composite could be explained by the mixture rule.With the high dielectric permittivity and tunable varistor behaviors,the composite ceramics has a potential application for the higher voltage transportation devices.