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Doping Effects on Electronic conductivity and Electrochemical Performance of LiFePO_4

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Journal of Materials Science & Technology 2009年第3期25卷 405-409页

作者： Jiezi Hu Jian Xie Xinbing Zhao Hongming Yu Xin Zhou Gaoshao Cao Jiangping Tu State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Department of Chemistry Mie University 1577 Kurimamachiyacho Tsu Mie 514-8507 Japan

Olivine-structured pure LIFePO4 and doped LI（M, Fe）PO4 （M=La, Ce, Nd, Mn, Co, Ni） have been synthesized by a solvothermal method. X-ray diffraction and field emission scanning electron microscopy analyses indicate that the as-prepared LiFePO4 is well-crystallized nanopowders without any detectable impurity phases. The electronic conductivity of LiFePO4 is enhanced by around 1-3 orders by doping. It was found that doping alone is not sufficient for the high-rate performance of LiFePO4 and surface coating with such as carbon should be needed. The best dopant for LiFePO4 is Nd among those studied in the present work. Accordingly, doping with 1 mol fraction Nd leads to an increase in 70 mAh/g at 0.1 C for the hydrothermally synthesized sample and 50 mAh/g at 1.0 C after carbon-coating in comparison with the undoped samples.

关键词： Lithium iron phosphate Doping conductivity Hydrothermal synthesis

Preparation and conductivity of nanocrystalline rare earth mixed oxides SmFe_(1-x),Co_xO_(3-δ)

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Rare Metals 2002年第3期21卷 190-192页

作者： RENYinzhe WANGYuxiang 等 DepartmentofChemstry ShanxiNormalUniversityLinfen041004China LinfenNormalCollegeofShanxiNormalUniversity Linfen041004China

Nanocrystalline rare earth mixed oxides SmFe_(1-x)Co_xO_(3-delta) wereprepared by sol-gel method at 1 073 K for 2 h calcination and characterized by X-ray diffraction(XRD) and scanning electron microscope (SEM). The results show that SmFe_(1-x)Co_xO_(3-delta) hasthe structure of perovskite type. The conductivity of the materials increases with the temperaturerising and the maximum conductivity at 1 073 K is 2.6 S/cm with the best mole ratio of Fe^(3+) toCo^(3+) being 1: 4. This kind of oxide is a conductive ceramic material by means of conduction ofelectron and oxygen anion.

关键词： nanocrystalline rare earth SmFe_(1-x)Co_xO_(3-delta) conductivity

Zintl Phase BaAgSb: Low Thermal conductivity and High Performance Thermoelectric Material in Ab Initio Calculation

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Chinese Physics Letters 2021年第4期38卷 87-90页

作者：王绍菲张志刚王保田张俊荣王芳卫 Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523808China School of Nuclear Sciences and Technology University of Chinese Academy of SciencesBeijing 100049China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Material Laboratory Dongguan 523808China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

Thermoelectric materials are critical parts in thermal electric devices.Here,Zintl phase BaAgSb in space group of P63/mmc is reported as a promising thermoelectric material in density function theory.The anisotropic lattice thermal conductivity and phonon transport properties are investigated in theory.The strong phonon-phonon scattering in BaAgSb exhibits ultra-low lattice thermal conductivity of 0.59 W·m^(-1)·K^(-1) along c-axis at 800 K,and high thermoelectric performance ZT=0.94 at 400 K.The mix of covalent and ionic bond supports high carrier mobility and low thermal conductivity.The unusual features make BaAgSb a potential thermoelectric material.

关键词： conductivity. theory. conductivity

Low-Frequency Dependence of conductivity and Dielectric Properties of Polyaniline/ZnFe_(2)O_(4) Nanocomposites

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Chinese Physics Letters 2011年第11期28卷 218-221页

作者： G.D.Prasanna H.S.Jayanna Ashok R Lamani M.L.Dinesha C.S.Naveen G.J.Shankaramurthy Department of PG Studies and Research in Physics Kuvempu UniversityShankarghatta-577451KarnatakaIndia Bapuji Institute of Engineering and Technology Davangere-577004KarnatakaIndia

Conducting polyaniline/ZnFe_(2)O_(4) nanocomposites are synthesized by using a simple and inexpensive one-step in-situ polymerization method in the presence of ZnFe2O4 nanoparticles.The structural,morphological and electrical properties of the samples are characterized by x-ray diffraction,Fourier transform infrared spectra and scanning electron microscopy.These results reveal the formation of polyaniline/ZnFe2O4 nanocomposites.The morphology of these samples is studied by scanning electron microscopy.Further,the ac conductivity(σac)of these composites is investigated in the frequency range of 1 kHz–10 MHz.The presence of polarons and bipolarons are responsible for the frequency dependence of ac conductivity in these nanocomposites.The ac conductivity is found to be constant up to 1MHz and thereafter it increases steeply.The ac conductivity of 0.695 S・cm^(−1) at room temperature is observed as the maxima for the polyaniline with 40wt%of the ZnFe2O4 nanocomposite.

关键词： composites ZnFe2O4 conductivity

Chiral Fermion conductivity in Graphene-Like Samples Subjected to Orthogonal Fields

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Chinese Physics Letters 2012年第1期29卷 20-23页

作者： Ciprian Dariescu Marina-Aura Dariescu Faculty of Physics Alexandru Ioan Cuza University of IaşiBd.Carol I No.11700506 IaşiRomania

Starting with the U(1)-gauge covariant four-dimensional Dirac equation,we derive the analytic solutions describing the chiral massless fermions evolving in static orthogonal magnetic and electric fields.Working in cylindric coordinates,we compute the electric current density essential component and the off-diagonal conductivities.By summing up the conductivities of the two distinct species of electrons connected to the orientation of spin,the well-known 4n-quantization law is restored.

关键词： Fermi diagonal conductivity

Study　on　the　conductivity　of　BaPbO_3-Nd_2O_3　System　Ceramics

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Journal of Rare Earths 1997年第1期15卷 67-69页

作者：肖鸣山王成建张承琚王希香兰建胜陈洪存 Department of Physics Shandong University Jinan 250100 China

In this paper, the conductivities of BaPbO 3 and BaPbO 3-Nd 2O 3 system ceramics are studied. The experimental results show that the charge carriers in this system ceramics are donor electrons captured in oxygen vacancies. The conductivity and the PTC characteristics of the BaPbO 3-Nd 2O 3 ceramics are obviously different from those of pure BaPbO ceramics.

关键词： BaPbO 3-Nd 2O 3 system ceramics conductivity PTC characteristics Rare earth

Far-infrared conductivity of CuS nanoparticles measured by terahertz time-domain spectroscopy

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Chinese Physics B 2010年第4期19卷 213-217页

作者：杨玉平张振伟施宇蕾冯帅王文忠 School of Science Minzu University of China Department of Physics Capital Normal University

This paper reports that terahertz time-domain spectroscopy is used to measure the optical properties of CuS nanoparticles in composite samples. The complex conductivity of pure CuS nanoparticles is extracted by applying the Bruggeman effective medium theory. The experimental data are consistent with the Drude-Smith model of conductivity in the range of 0.2 1.5 THz. The results demonstrate that carriers become localized with a backscattering behaviour in small-size nanostructures. In addition, the time constant for the carrier scattering is obtained and is only 64.3 fs due to increased electron interaction with interfaces and grain boundaries.

关键词： terahertz time-domain spectroscopy conductivity effective medium theory Drude-Smith model

Simultaneous Enhancement of Electrical conductivity and Seebeck Coefficient of Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate)Films Treated with Urea

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Chinese Physics Letters 2011年第3期28卷 191-194页

作者：孔芳芳刘聪聪徐景坤蒋丰兴卢宝阳岳瑞瑞刘国栋王建民 Jiangxi Key Laboratory of Organic Chemistry Jiangxi Science and Technology Normal UniversityNanchang 330013 School of Communication and Electronics Jiangxi Science and Technology Normal UniversityNanchang 330013

The thermoelectric performance of free-standing poly(3,4-ethylenedioythiophene):poly(styrenesulfonate)(PEDOT:PSS)thin films deposited from aqueous dispersion treated by different concentrations of urea are investigated in detail.The electrical conductivity,Seebeck coefficient and power factor of PEDOT:PSS films versus temperature are determined,respectively.It is found that both the electrical conductivity and Seebeck coefficient of PEDOT:PSS films are enhanced after treatment with urea.conductivity could be enhanced from 8.16 to 63.13S-cm^(-1),the Seebeck coefficient is increased from 14.47 to 20.7μV.K^(-1)and the power factor is rises to 2.7μW.m^(-1)K^(-2)at 300K.

关键词： Seebeck conductivity electrical

THERMAL conductivity OF Al-Li ALLOY AT CRYOGENIC TEMPERATURES

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中国有色金属学会会刊：英文版 1996年第4期6卷 127-129页

作者： Sun Dongsheng Li engzhao Shang Lei(Department of Materials Science and Engineering,Shandong Univesity of Technology,Jinan 250014) Department of Materials Science and Engineering Shandong Univesity of Technology Jinan 250014 China

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关键词： thermal conductivity Al-Li alloy cryogenic temperatures