Ionic Conductivity and Solid Electrolytes

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "Ionic Conductivity and Solid Electrolytes"

Transcription

1 Ionic Conductivity and Solid Electrolytes Ceramic insulators The primary function of insulation in electrical circuits is physical separation of conductors and regulation or prevention of current flow between them. Other functions are to provide mechanical support, heat dissipation, and environmental protection for conductors. Ceramic materials which in use these functions are classified as ceramic insulators. They include most glasses, porcelains, and oxide and nitride materials. The advantage of ceramics as insulators is their capability for high-temperature operation. Insulation Resistance Insulation Resistance Conductivity = d/(r A) and 1/ = = (R A)/d Or in terms of the material parameters = nq where is the electrical resistivity (m), R () the sample resistance, A is area (m ), and d thickness (m). If more than one type of charge carrier being present, the resultant conductivity can be defined as the sum of component conductivities ( I ) as follows: = i n i (ez) i i = i i Depending on which charge carriers predominate, the solid may be classified as primarily an electronic (n or p type) or ionic conductor. However, mixed conduction is = electronic + ionic Insulation Resistance Insulation Resistance For an ionic solid, mobility is related to the diffusion coefficient D (cm /sec) by the Einstein relationship = ezd/kt Diffusion and conductivity are related by the Nernst- Einstein equation: = n(ez) D/kT Since both diffusion and N (number of defects generated) are activated processes, where N = n exp(-w/kt) Then and D = D o exp(- /kt) = o exp(-e/kt) E = w/ + Where w and are activation energies for defect generation and migration. For extrinsic conduction w=0 and E=; that is, the ionic mobility becomes the controlling factor in the conduction. 1

2 What is an ion? An ion is a positive or negative loaded atom caused by electron deficiency or electron excess. This electron deficiency/excess arises at the reaction of two atoms (ionic connection). Positive loaded ions are called cations and negative loaded ions are called anions. In ionic crystal, the individual lattice atoms transfer electron between each other to form positively charged cations and negatively charged anions. The binding forces between ions are electrostatic in nature and thus very strong. The RT conductivity of ionic crystals is much lower than the conductivity of typical metallic conductors. The large difference in conductivity can be understood by realizing that the wide bandgap in insulators allows only extremely few electrons to become excited from the valence band into the conduction band. Ionic conduction is caused by the movement of some negatively (or positively) charged ions which hop from lattice site to lattice site under the influence of an electric field. This ionic conductivity: ion Nion eion (1) In order for ions to move through a crystalline solid, they must have sufficient energy to pass over an energy barrier (see schematic). Thus, N ion in eq.(1) depends on the vacancy concentration in the crystal (i.e., on the number of Schottky defects). N ion is the number of ions per unit volume that can change their position under the influence of an electric field ion is the mobility of these ions. E d (a) Q distance E (b) distance Figure: Schematic representation of a potential barrier, which an ion ( ) has to overcome to exchange its site with a vacancy ( ). (a) Without an external electric field, (b) with an external electric field. d = distance between two adjacent, equivalent lattice sites, Q = activation energy. The D varies with temperature; this dependence is commonly expressed by an Arrhenius equation: Q D Do exp kbt () Where Q is the activation energy, D o is a preexponential factor that depends on the vibrational frequency of the atoms and some structural parameters.

3 Combining (1) through () yields, Nion e Do Q ion exp kbt kbt (3) Equation (3) is shortened by combining the preexponential constant: Q ion o exp kbt (4) If plotted ln ion vs. 1/T, a straight line with a negative slope would result. (See figure). The slopes in Arrhenius plots are utilized to calculate the activation energy, Q or Ea. Taking the natural logarithm yields: Q 1 ln ion ln o (5) kb T ln ion Q 1 ln o kb T Slope = - Q/k For SiO from graph: Slope = (ln 10-7 ln )/(1.5x x10-3 ) = [ln (10-7 /10-14 )]/(-1x10-3) = ln 10 7 /(-1x10-3 ) = x10 4 From Slope = - Q/k Q = (1.61x10 4 )x(1.3806x10-3 ) =.5x10-19 J Q = 1.39 ev (1 ev = 1.6x10-19 J) Sometimes, ln vs. 1/T plot will give us two () line regions representating of two different Q values. ln T( o C) 1/T Figure: Schematic representation of ln versus 1/T for Na + ions in Na. (Arrhenius plot). At low T, the Q is small, the thermal energy is just sufficient to allow the hopping of ions into already existing vacancy sites. This T range is commonly called the extrinsic region. 非本征区域 At high T, the thermal energy is large enough to create additional vacancies. The related Q is thus the sum of the Q for vacancy creation and ion movement. This T range is called the intrinsic region. 本征区域 High Conducting Ceramics Ceramics are generally classified as electronic conductors, ionic conductors, mixed (electronic/ionic) conductors, and insulators. The electronic conductors include superconductors, and semiconductors. Ionic conductors generally exhibit conductivities in the range 10-1 to 100 S m -1 that increase exponentially with temperature. Insulators such as high-purity alumina are at the lower extreme of the conductivity of S m -1. 3

4 Temperature Sensitive Resistor Some ceramic resistors exhibit high value of the temperature coefficient of resistance (TCR) and they may be negative (NTC) or positive (PTC). Temperature Sensitive Resistor In a ceramic a large temperature coefficient of resistivity can arise from 3 causes: The intrinsic characteristic. A structure transition which accomponied by a change in the conduction mechanism from semiconducting to metallic. A rapid change in dielectric properties in certain ceramics which affects the electronic properties in the intergranular region to give rise to a large increase in resistivity with temperature over small temperature range. The 3 rd Mechanism has led to important TCR devices. NTC Thermistor The TCR of a semiconductor is expected to be negative. In each case the resistivity depends on temperature according to B ( T) exp T where is approximately independent of T and B is a constant related to the energy required to active the electron to conduct. Differentiating this equation leads to TCR value R : Typical resistance-temperature response for various sensor materials 1 d B R dt T NTC Thermistor The most NTC materials are based on solid solutions of oxides with spinel structure, e.g. Fe 3 O 4 -ZnCr O 4 and Fe 3 O 4 -MgCr O 4. A series that gives favorable combinations of low resistivity and high coefficients is based on Mn 3 O 4 with a partial replacement of Mn by Ni, Co and Cu. PTC Thermistor PTC thermistors exhibit an increase in resistance at a specified temperature. PTC resistor could be classified as critical temperature resistors because, in the case of the most widely used type The positive coefficient is associated with the ferroelectric Curie point. 4

5 PTC Thermistor Most PTC has the negative resistivity-temperature characteristic up to about 100 o C and above about 00 o C. While between these temperatures there is an increase of several orders of magnitude in resistivity. The PTC effect is exhibited by specially doped and processed (eg. BaTiO 3). Application of PTC Thermistor The are two main groups: Applications such as temperature measurement, temperature control, temperature compensation and overtemperature protection. The second group includes applications such as over-current protection, liquid level detection and time delay. Voltage-dependent Resistors (Varistors) There are a number of situations in which it is valuable to have a resistor which offers a high resistance at low voltages and a low resistance at high voltages. Such a devices can be used to protect a circuit from high-voltage transients by providing a path across the power supply that takes only a small current under normal conditions but takes large current if the voltage rises abnormally, thus preventing high-voltage pulses from reaching the circuit. Schematic use of a VDR to protect a circuit against transients, Source VDR Circuit to be protected Varistors-VDR Ceramics based on SiC and ZnO are two materials in everyday use for VDR. The VDR behaviour in ZnO varistors for example is governed by electron states that are formed on the surfaces of crystals as a consequence of the discontinuity. These surface states act as acceptors for electrons from the n- type semiconductor. Electrons will be withdrawn from region near the surface and replaced by a positive space charge. Oppositely oriented Schottky barrier will be created at surface of neihbouring crystals so that a high resistance will be offered to electron flow in either direction. Illustrations of actual microstructure of a varistor 5

6 Basic principles of Varistors-VDR At low applied fields small thermally activated currents pass over the reverse biased junction. At high fields tunneling through the junction will occur, accounting for the low resistance. The behavior is similar in some respects to Zener diodes. From varistor I-V characteristic, the linear part can be represented by the relation, I kiu Where k I is a constant and falls off at low voltages. If I 1 and I are currents at voltages that differ by factor of 10, log I 1 10, I I I 1 Basic principles of Varistors-VDR Alternatively, where U k The resistance at a given voltage is R kv I Power dissipated is V 1/ and k V k with = 5, a 10 % increase in voltage would increase the power dissipation by a factor about.5. I P IU k U I 1 1/ I U k 1 1 ( 1) I Solid Electrolytes Electrolyte - A substance that conducts electricity through the movement of ions. Most electrolytes are solutions or molten salts, but some electrolytes are solids and some of those are crystalline solids. Different names are given to such materials: Solid Electrolyte Fast Ion Conductor Superionic Conductor we will be looking at materials which behave as solid electrolytes, their properties and applications. Ionic vs. Electronic Conductivity Let s begin by comparing the properties of ionic conductors with the conventional electronic conductivity of metals. Metals Conductivity Range = 10 S/cm < s < 10 5 S/cm Electrons carry the current Conductivity Increases linearly as temperature decreases (phonon scattering decreases as T ) Solid Electrolytes Conductivity Range = 10-3 S/cm < s < 10 S/cm Ions carry the current Conductivity decreases exponentially as temperature decreases (activated transport) Defects In order for an ion to move through a crystal it must hop from an occupied site to a vacant site. Thus ionic conductivity can only occur if defects are present. The two simplest types of point defects are Schottky and Frenkel defects. Ion Migration (Schottky Defects) Consider the movement of Na + ions in Na via vacancies originating from Schottky defects. Note that the Na + ion must squeeze through the lattice, inducing significant local distortion/relaxation. This is one factor that limits the mobility of ions. A second factor that contributes is the relatively high probability that the ion will jump back to it s original position, leading to no net ionic migration. Na Na E Schottky Defect (i.e. Na) Na V na + V Frenkel Defect (i.e. ) + V + + interstitial Na To get across the unit cell into the vacancy the Na + ion must hop through the center of the cube where it squeezes by 4 - and Na +. The energy of this transition state will determine the ease of migration. Chem Solid State Chemistry 6

7 Ion Migration (Frenkel Defects) The Frenkel defects in can migrate via two mechanisms. 1 1 Direct Interstitial Jump 1 1 Interstitialcy Mechanism 由于离子的可移动性比电子要小得多, 用霍尔效应测定载流子为何种离子是不大可能的 Conductivity 1.31 Ω-1 cm -1 Applications of Ionic Conductors There are numerous practical applications, all based on electrochemical cells, where ionic conductivity is needed and it is advantageous/necessary to use solids for all components. Batteries Fuel Cells Gas Sensors e - Useful Power Electrolyte Anode Cathode In such cells ionic conductors are needed for either the electrodes, the electrolyte or both. Electrolyte (Material needs to be an electrical insulator to prevent short circuit) Electrode (Mixed ionic and electronic conductivity is needed to avoid open circuit) Schematic of a Solid Oxide Fuel Cell g 1 O e O O (s) H H O(g) e s _ shtml 上海硅酸盐所固体氧化物燃料电池研究取得进展 燃料电池电池工作原理 氢燃料电池 甲醇等小分子燃料电池 燃料电池分类 7

8 质子交换膜燃料电池 (PEMFC) 简介 质子交换膜燃料电池 (proton exchange membrane fuel cell, 英文简称 PEMFC) 是一种燃料电池, 在原理上相当于水电解的 逆 装置 其单电池由阳极 阴极和质子交换膜组成, 阳极为氢燃料发生氧化的场所, 阴极为氧化剂还原的场所, 两极都含有加速电极电化学反应的催化剂, 质子交换膜作为电解质 工作时相当于一直流电源, 其阳极即电源负极, 阴极为电源正极 两电极的反应分别为 : 阳极 ( 负极 ):H -4e=4H + 阴极 ( 正极 ):O +4e+4H+=H O 碱性燃料电池 (AFC) 简介 使用的电解质为水溶液或稳定的氢氧化钾基质, 且电化学反应也与羟基 (-OH) 从阴极移动到阳极与氢反应生成水和电子略有不同 这些电子是用来为外部电路提供能量, 然后才回到阴极与氧和水反应生成更多的羟基离子 负极反应 :H + 4OH - 4 H O + 4e - 正极反应 :O + H O + 4 e - 4OH - 质子交换膜燃料电池优点 : 其发电过程不涉及氢氧燃烧, 因而不受卡诺循环的限制, 能量转换率高 ; 发电时不产生污染, 发电单元模块化, 可靠性高, 组装和维修都很方便, 工作时也没有噪音 所以, 质子交换膜燃料电池电源是一种清洁 高效的绿色环保电源 质子交换膜燃料电池工作温度低 启动快 比功率高 结构简单 操作方便等 碱性电池的优点 : 效率高, 因为氧在碱性介质中的还原反应比其他酸性介质高 ; 因为是碱性介质, 可以用非铂催化剂, 廉价 因工作温度低, 碱性介质, 所以可以采用镍板做双极板 Schematic of Rechargeable Li Battery Taken from A. Manthiram & J. Kim Low Temperature Synthesis of Insertion Oxides for Lithium Batteries, Chem. Mater. 10, (1998). Solid Electrolyte Materials + Ion Conductors I & Rb 4 I 5 Na + Ion Conductors Sodium -Alumina (i.e. NaAl 11 O 17, Na Al 16 O 5 ) NASICON (Na 3 Zr PSi O 1 ) Li + Ion Conductors LiCoO, LiNiO LiMnO O - Ion Conductors Cubic stabilized ZrO (Y x Zr 1-x O -x/, Ca x Zr 1-x O -x ) -Bi O 3 Defect Perovskites (Ba In O 5, La 1-x Ca x MnO 3-y, ) F - Ion Conductors PbF & AF (A = Ba, Sr, Ca) Stabilized ZrO is not a good ionic conductor at low temperature. -I & Rb 4 I 5 have ionic conductivities comparable to conc. H SO 4 Chem Solid State Chemistry Taken from Solid State Chemistry and its Applications by Anthony West General Characteristics: Solid Electrolytes 1. A large number of the ions of one species should be mobile. This requires a large number of empty sites, either vacancies or accessible interstitial sites. Empty sites are needed for ions to move through the lattice.. The empty and occupied sites should have similar potential energies with a low activation energy barrier for jumping between neighboring sites. High activation energy decreases carrier mobility, very stable sites (deep potential energy wells) lead to carrier localization. 3. The structure should have solid framework, preferable 3D, permeated by open channels. The migrating ion lattice should be molten, so that a solid framework of the other ions is needed in order to prevent the entire material from melting. 4. The framework ions (usually anions) should be highly polarizable. Such ions can deform to stabilize transition state geometries of the migrating ion through covalent interactions. 8

9 + Ion Conductors -I Stable below 146 ºC Wurtzite Structure (tetrahedral coordination) s = S/cm S/cm -I Stable above 146 ºC BCC Arrangement of I -, molten/ disordered + s ~ 1 S/cm, E A =0.05 ev Conductivity decreases on melting Rb 4 I 5 Highest known conductivity at room temperature BCC Arrangement of I -, molten/disordered + s ~ 0.5 S/cm (5 ºC), E A =0.07 ev Na + Ion Conductors Na 3 Zr PSi O 1 (NASICON) Framework of corner sharing ZrO 6 octhahedra and PO 4 /SiO 4 tetrahedra Na + ions occupy trigonal prismatic and octahedral sites, ¼ of the Na + sites are empty E A ~ 0.3 ev NaAl 7 O 11 (Na O. nal O 3 ) FCC like packing of oxygen Every fifth layer ¾ of the O - ions are missing, Na + ions present. These layers are sandwiched between spinel blocks. D ionic conductor Chem Solid State Chemistry Favored Materials (SOFC) Cathode (Air Electrode) (La 1-x Ca x )MnO 3 (Perovskite) (La 1-x Sr x )(Co 1-x Fe x )O 3 (Perovskite) (Sm 1-x Sr x )CoO 3 (Perovskite) (Pr 1-x Sr x )(Co 1-x Mn x )O 3 (Perovskite) Anode (H /CO Electrode) Ni/Zr 1-x Y x O Composites Electrolyte (Air Electrode) Zr 1-x Y x O (Fluorite) Ce 1-x R x O, R = Rare Earth Ion (Fluorite) Bi -x R x O 3, R = Rare Earth Ion (Defect Fluorite) Gd 1.9 Ca 0.1 Ti O 6.95 (Pyrochlore) (La,Nd) 0.8 Sr 0. Ga 0.8 Mg 0. O.8 (Perovskite) Interconnect (between Cathode and Anode) La 1-x Sr x CrO 3 (Perovskite) Chem Solid State Chemistry The partial pressure of oxygen in the sample gas, P O (sample), can be determined from the measured potential, V, via the Nernst equation. Because of the low ionic conductivity at low temperatures, the sensor is only useful above 650 ºC. O Gas Sensor V = (RT/4F) ln[{(p O (ref.)}/{(p O (sample)}] See for details Application: Sensors Example: Oxygen sensor ZrO Principle: Make diffusion of ions fast for rapid response. Approach: Add Ca impurity to ZrO: -- increases O - vacancies -- increases O - diffusion rate Operation: -- voltage difference produced when O - ions diffuse from the external surface of the sensor to the reference gas. Ca + gas with an unknown, higher Oxyge n content A Ca + impurity removes a Zr 4+ and a O - ion. sensor reference gas at fixed O - oxygen content diffusion + voltage difference produced! - Design Principles: O - Conductors High concentration of anion vacancies necessary for O - hopping to occur High Symmetry provides equivalent potentials between occupied and vacant sites High Specific Free Volume (Free Volume/Total Volume) void space/vacancies provide diffusion pathways for O - ions Polarizable cations (including cations with stereoactive lone pairs) polarizable cations can deform during hopping, which lowers the activation energy Favorable chemical stability, cost and thermal expansion characteristics for commercial applications 9

10 Phase Transitions in ZrO Room Temperature Monoclinic (P 1 /c) 7 coordinate Zr 4 coord. + 3 coord. O - High Temperature(500 o C) Cubic (Fm3m) cubic coordination for Zr tetrahedral coord. for O - Effect of Dopants: ZrO, CeO Doping ZrO (Zr 1-x Y x O -x/, Zr 1-x Ca x O -x ) fulfills two purposes Introduces anion vacancies (lower valent cation needed) Stabilizes the high symmetry cubic structure (larger cations are most effective) We can also consider replacing Zr with a larger cation (i.e. Ce 4+ ) in order to stabilize the cubic fluorite structure, or with a lower valent cation (i.e. Bi 3+ ) to increase the vacancy concentration. Compound r 4+ Specific Free Conductivity (Angstroms) 800ºC Zr 0.8 Y 0. O S/cm Ce 0.8 Gd 0. O S/cm -Bi O S/cm (730ºC) Bi O 3 is only cubic from 730ºC to it s melting point of 830ºC. Doping is necessary to stabilize the cubic structure to lower temps. Gd Ti O 7 Pyrochlore 烧绿石 Ba In O 5 Brownmillerite 钙铁石 The pyrochlore structure can be derived from fluorite, by removing 1/8 of the oxygens, ordering the two cations and ordering the oxygen vacancies. By replacing some of the Gd 3+ with Ca + oxygen vacancies in the A O network are created, significantly increasing the ionic conductivity (at 1000ºC): Gd Ti O 7 s = S/cm, E A = 0.94 ev Gd 1.8 Ca 0. Ti O 6.95 s = S/cm, E A = 0.63 ev There is an opportunity to obtain mixed electronic-ionic conductivity in the pyrochlore structure. M O 6 Network A O Network The brownmillerite structure can be derived from perovskite, by removing 1/6 of the oxygens and ordering the vacancies so that 50% of the smaller cations are in distorted tetrahedral coordination. In Ba In O 5 at 800 ºC the oxygen vacancies disorder throughout the tetrahedral layer, and the ionic conductivity jumps from 10-3 S/cm to 10-1 S/cm. BaZrO 3 -Ba In O 5 solid solutions absorb water to fill oxygen vacancies and become good proton conductors over the temperature range ºC. Tetrahedral Layer Octahedral Layer Aurivillius and BIMEVOX phases Bi WO 6 is a member of the Aurivilius structure family. The structure contains D perovskite-like sheets made up of corner sharing octahedra, stacked with Bi O + layers. Bi 4 V O 11 is a defect Aurivillius phase, better written as (Bi O )VO 3.5, where 1/8 of the oxygen sites in the perovskite layer are vacant. Conductivity at 600 ºC is the highest ever reported for an O - conductor ~ 0. S/cm. Only the perovskite oxygens are mobile. Normally Bi 4 V O 11 undergoes phase transitions upon cooling that lower it s ionic conductivity, but doping onto the V site stabilizes the HT phase. These phases are generally called BIMEVOX phases. (Bi O )V 0.9 Cu 0.1 O 3.35 has a conductivity of 0.01 S/cm at 350 ºC!! Summary O - Conductors It is generally true that dopants have to be added either to introduce vacancies, or to stabilize the high temperature/high symmetry phase Among fluorite based O - conductors both doped CeO and Bi O 3 have higher conductivities than stabilized ZrO, but both are less chemically stable. In particular they are prone to reduction. This limits their use. Brownmillerite 钙铁石 conductors show high conductivity, but are prone to become electrically conducting under mildly reducing conditions. They show promise as proton conductors. Ionic conductors based on Bi 4 V O 11 (BIMEVOX) show very high conductivity for low temperature applications. 10

Synthesis of anisole by vapor phase methylation of phenol with methanol over catalysts supported on activated alumina

Synthesis of anisole by vapor phase methylation of phenol with methanol over catalysts supported on activated alumina Chinese Journal of Catalysis 37 (216) 72 726 催化学报 216 年第 37 卷第 5 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Synthesis of anisole by vapor

More information

Electrical Conduction in Ceramic Materials 1 Ref: Barsoum, Fundamentals of Ceramics, Ch7, McGraw-Hill, 2000

Electrical Conduction in Ceramic Materials 1 Ref: Barsoum, Fundamentals of Ceramics, Ch7, McGraw-Hill, 2000 MME 467 Ceramics for Advanced Applications Lecture 19 Electrical Conduction in Ceramic Materials 1 Ref: Barsoum, Fundamentals of Ceramics, Ch7, McGraw-Hill, 2000 Prof. A. K. M. B. Rashid Department of

More information

Effect of lengthening alkyl spacer on hydroformylation performance of tethered phosphine modified Rh/SiO2 catalyst

Effect of lengthening alkyl spacer on hydroformylation performance of tethered phosphine modified Rh/SiO2 catalyst Chinese Journal of Catalysis 37 (216) 268 272 催化学报 216 年第 37 卷第 2 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Effect of lengthening alkyl

More information

Recent progress in Ag3PO4 based all solid state Z scheme photocatalytic systems

Recent progress in Ag3PO4 based all solid state Z scheme photocatalytic systems Chinese Journal of Catalysis 38 (2017) 1794 1803 催化学报 2017 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Minireview Recent progress in

More information

Source mechanism solution

Source mechanism solution Source mechanism solution Contents Source mechanism solution 1 1. A general introduction 1 2. A step-by-step guide 1 Step-1: Prepare data files 1 Step-2: Start GeoTaos or GeoTaos_Map 2 Step-3: Convert

More information

Highly effective electrochemical water oxidation by copper oxide film generated in situ from Cu(II) tricine complex

Highly effective electrochemical water oxidation by copper oxide film generated in situ from Cu(II) tricine complex Chinese Journal of Catalysis 39 (218) 479 486 催化学报 218 年第 39 卷第 3 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue of Photocatalysis

More information

Proton gradient transfer acid complexes and their catalytic performance for the synthesis of geranyl acetate

Proton gradient transfer acid complexes and their catalytic performance for the synthesis of geranyl acetate Chinese Journal of Catalysis 37 (216) 2114 2121 催化学报 216 年第 37 卷第 12 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Proton gradient transfer

More information

Magnetic Co/Al2O3 catalyst derived from hydrotalcite for hydrogenation of levulinic acid to γ-valerolactone

Magnetic Co/Al2O3 catalyst derived from hydrotalcite for hydrogenation of levulinic acid to γ-valerolactone Chinese Journal of Catalysis 36 (2015) 1512 1518 催化学报 2015 年第 36 卷第 9 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Communication (Special Issue for Excellent

More information

Effect of promoters on the selective hydrogenolysis of glycerol over Pt/W containing catalysts

Effect of promoters on the selective hydrogenolysis of glycerol over Pt/W containing catalysts Chinese Journal of Catalysis 37 (2016) 1513 1520 催化学报 2016 年第 37 卷第 9 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Effect of promoters on

More information

Growth of Cu/SSZ 13 on SiC for selective catalytic reduction of NO

Growth of Cu/SSZ 13 on SiC for selective catalytic reduction of NO Chinese Journal of Catalysis 39 (2018) 71 78 催化学报 2018 年第 39 卷第 1 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Growth of Cu/SSZ 13 on SiC

More information

The preload analysis of screw bolt joints on the first wall graphite tiles in East

The preload analysis of screw bolt joints on the first wall graphite tiles in East The preload analysis of screw bolt joints on the first wall graphite tiles in East AO ei( 曹磊 ), SONG Yuntao( 宋云涛 ) Institute of plasma physics, hinese academy of sciences, Hefei 230031, hina Abstract The

More information

N doped ordered mesoporous carbon as a multifunctional support of ultrafine Pt nanoparticles for hydrogenation of nitroarenes

N doped ordered mesoporous carbon as a multifunctional support of ultrafine Pt nanoparticles for hydrogenation of nitroarenes Chinese Journal of Catalysis 38 (2017) 1252 1260 催化学报 2017 年第 38 卷第 7 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article N doped ordered mesoporous

More information

Atomic & Molecular Clusters / 原子分子团簇 /

Atomic & Molecular Clusters / 原子分子团簇 / Atomic & Molecular Clusters / 原子分子团簇 / 王金兰 Email: jlwang@seu.edu.cn Department of Physics Southeast University What is nanometer? Nano is Small (10-7 --10-9 m; 1-100 nm) 10 0 m 10-1 m 10-2 m 10-3 m 10-4

More information

Chapter 10 ALCOHOLS, PHENOLS, AND ETHERS

Chapter 10 ALCOHOLS, PHENOLS, AND ETHERS Chapter 10 ALCOHOLS, PHENOLS, AND ETHERS The next several chapters deal with the chemistry of various oxygen-containing functional groups. The interplay of these important classes of compounds alcohols,

More information

One step synthesis of graphitic carbon nitride nanosheets for efficient catalysis of phenol removal under visible light

One step synthesis of graphitic carbon nitride nanosheets for efficient catalysis of phenol removal under visible light Chinese Journal of Catalysis 38 (217) 1711 1718 催化学报 217 年第 38 卷第 1 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article One step synthesis of graphitic

More information

available at journal homepage:

available at  journal homepage: Chinese Journal of Catalysis 36 (2015) 15801586 催化学报 2015 年第 36 卷第 9 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue for Excellent

More information

SnO2 based solid solutions for CH4 deep oxidation: Quantifying the lattice capacity of SnO2 using an X ray diffraction extrapolation method

SnO2 based solid solutions for CH4 deep oxidation: Quantifying the lattice capacity of SnO2 using an X ray diffraction extrapolation method Chinese Journal of Catalysis 37 (2016) 1293 1302 催化学报 2016 年第 37 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article SnO2 based solid solutions

More information

NANOMATERIALES DE CARBONO

NANOMATERIALES DE CARBONO 29 Resultados Datos actualizados a 02/01/2018 [17:04:00] Solicitudes publicadas en los últimos 60 días (excluida automoción) / Applications published in the last 60 days (Automotion publications excluded)

More information

Giant magnetoresistance in Fe/SiO 2 /p-si hybrid structure under non-equilibrium conditions

Giant magnetoresistance in Fe/SiO 2 /p-si hybrid structure under non-equilibrium conditions Trans. Nonferrous Met. Soc. China 24(2014) 3158 3163 Giant magnetoresistance in Fe/SiO 2 /p-si hybrid structure under non-equilibrium conditions N. V. VOLKOV 1, 2, A. S. TARASOV 1, A. O. GUSTAJCEV 1, 2,

More information

High performance ORR electrocatalysts prepared via one step pyrolysis of riboflavin

High performance ORR electrocatalysts prepared via one step pyrolysis of riboflavin Chinese Journal of Catalysis 38 (2017) 1668 1679 催化学报 2017 年第 38 卷第 10 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article igh performance RR electrocatalysts

More information

Selective reduction of carbon dioxide to carbon monoxide over Au/CeO2 catalyst and identification of reaction intermediate

Selective reduction of carbon dioxide to carbon monoxide over Au/CeO2 catalyst and identification of reaction intermediate Chese Journal of Catalysis 37 (216) 253 258 催化学报 216 年第 37 卷第 12 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Selective reduction of carbon

More information

Electrocatalytic water oxidation by a nickel oxide film derived from a molecular precursor

Electrocatalytic water oxidation by a nickel oxide film derived from a molecular precursor Chinese Journal of Catalysis 38 (2017) 1812 1817 催化学报 2017 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Electrocatalytic water

More information

available at journal homepage:

available at  journal homepage: Chinese Journal of Catalysis 38 (2017) 1860 1869 催化学报 2017 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Solid base catalysts

More information

Preparation of LaMnO3 for catalytic combustion of vinyl chloride

Preparation of LaMnO3 for catalytic combustion of vinyl chloride Chinese Journal of Catalysis 38 (2017) 1406 1412 催化学报 2017 年第 38 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Preparation of LaMnO3

More information

Synthesis of Ag/AgCl/Fe S plasmonic catalyst for bisphenol A degradation in heterogeneous photo Fenton system under visible light irradiation

Synthesis of Ag/AgCl/Fe S plasmonic catalyst for bisphenol A degradation in heterogeneous photo Fenton system under visible light irradiation Chinese Journal of Catalysis 38 (217) 1726 1735 催化学报 217 年第 38 卷第 1 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Synthesis of Ag/AgCl/Fe

More information

Low cost and efficient visible light driven microspheres fabricated via an ion exchange route

Low cost and efficient visible light driven microspheres fabricated via an ion exchange route Chinese Journal of Catalysis 38 (2017) 1899 1908 催化学报 2017 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Low cost and efficient

More information

Homogeneous boron doping in a TiO2 shell supported on a TiB2 core for enhanced photocatalytic water oxidation

Homogeneous boron doping in a TiO2 shell supported on a TiB2 core for enhanced photocatalytic water oxidation Chinese Journal of Catalysis 39 (218) 431 437 催化学报 218 年第 39 卷第 3 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue of Photocatalysis

More information

In situ preparation of mesoporous Fe/TiO2 catalyst using Pluronic F127 assisted sol gel process for mid temperature NH3 selective

In situ preparation of mesoporous Fe/TiO2 catalyst using Pluronic F127 assisted sol gel process for mid temperature NH3 selective Chinese Journal of Catalysis 38 (17) 1831 1841 催化学报 17 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article In situ preparation of mesoporous

More information

Module 3: Defects, Diffusion and Conduction in Ceramics Introduction. The Module contains: Diffusion. Diffusion Kinetics

Module 3: Defects, Diffusion and Conduction in Ceramics Introduction. The Module contains: Diffusion. Diffusion Kinetics Introduction In this module, we will discuss about migration of the defects which happens via an atomistic process called as diffusion. Diffusivity of species in the materials is also related to their

More information

Chapter 1 Linear Regression with One Predictor Variable

Chapter 1 Linear Regression with One Predictor Variable Chapter 1 Linear Regression with One Predictor Variable 許湘伶 Applied Linear Regression Models (Kutner, Nachtsheim, Neter, Li) hsuhl (NUK) LR Chap 1 1 / 41 Regression analysis is a statistical methodology

More information

Surface treatment effect on the photocatalytic hydrogen generation of CdS/ZnS core shell microstructures

Surface treatment effect on the photocatalytic hydrogen generation of CdS/ZnS core shell microstructures hinese Journal of atalysis 38 (217) 489 497 催化学报 217 年第 38 卷第 3 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc rticle Surface treatment effect on the

More information

Carbon film encapsulated Fe2O3: An efficient catalyst for hydrogenation of nitroarenes

Carbon film encapsulated Fe2O3: An efficient catalyst for hydrogenation of nitroarenes Chinese Journal of Catalysis 38 (2017) 1909 1917 催化学报 2017 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Carbon film encapsulated

More information

Simple synthesis of sub nanometer Pd clusters: High catalytic activity of Pd/PEG PNIPAM in Suzuki reaction

Simple synthesis of sub nanometer Pd clusters: High catalytic activity of Pd/PEG PNIPAM in Suzuki reaction Chinese Journal of Catalysis 38 (2017) 651 657 催化学报 2017 年第 38 卷第 4 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Simple synthesis of sub

More information

Novel structured Mo Cu Fe O composite for catalytic air oxidation of dye containing wastewater under ambient temperature and pressure

Novel structured Mo Cu Fe O composite for catalytic air oxidation of dye containing wastewater under ambient temperature and pressure Chinese Journal of Catalysis 38 (217) 1719 1725 催化学报 217 年第 38 卷第 1 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Novel structured Mo Cu Fe

More information

Unit wise Marks Distribution of 10+2 Syllabus

Unit wise Marks Distribution of 10+2 Syllabus Unit wise Marks Distribution of 10+2 Syllabus S.No Unit Name Marks 1 I Solid State 4 2 II Solutions 5 3 III Electro Chemistry 5 4 IV Chemical Kinetics 5 5 V Surface Chemistry 4 6 VI General Principles

More information

A review of the direct oxidation of methane to methanol

A review of the direct oxidation of methane to methanol Chinese Journal of Catalysis 37 (2016) 1206 1215 催化学报 2016 年第 37 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Review A review of the direct

More information

Catalytic combustion of methane over Pd/SnO2 catalysts

Catalytic combustion of methane over Pd/SnO2 catalysts Chinese Journal of Catalysis 38 (2017) 1322 1329 催化学报 2017 年第 38 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Catalytic combustion of

More information

Effect of the degree of dispersion of Pt over MgAl2O4 on the catalytic hydrogenation of benzaldehyde

Effect of the degree of dispersion of Pt over MgAl2O4 on the catalytic hydrogenation of benzaldehyde Chinese Journal of Catalysis 38 (2017) 1613 1620 催化学报 2017 年第 38 卷第 9 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue of the

More information

Hydrothermal synthesis of nanosized ZSM 22 and their use in the catalytic conversion of methanol

Hydrothermal synthesis of nanosized ZSM 22 and their use in the catalytic conversion of methanol Chinese Journal of Catalysis 37 (2016) 1381 1388 催化学报 2016 年第 37 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Hydrothermal synthesis

More information

Synthesis of FER zeolite with piperidine as structure directing agent and its catalytic application

Synthesis of FER zeolite with piperidine as structure directing agent and its catalytic application Chinese Journal of Catalysis 38 (2017) 1880 1887 催化学报 2017 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Synthesis of FER zeolite

More information

Tuning the growth of Cu MOFs for efficient catalytic hydrolysis of carbonyl sulfide

Tuning the growth of Cu MOFs for efficient catalytic hydrolysis of carbonyl sulfide Chinese Journal of Catalysis 38 (17) 1373 1381 催化学报 17 年第 38 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Tuning the growth of Cu MOFs

More information

Defects. Defects. Kap. 3 States of aggregation. Perfect Crystal

Defects. Defects. Kap. 3 States of aggregation. Perfect Crystal Kap. 3 States of aggregation Defects Perfect Crystal A A perfect crystal with every atom in the correct position does not exist. Only a hypothetical situation at 0 K Crystals are like people: it is the

More information

0 0 = 1 0 = 0 1 = = 1 1 = 0 0 = 1

0 0 = 1 0 = 0 1 = = 1 1 = 0 0 = 1 0 0 = 1 0 = 0 1 = 0 1 1 = 1 1 = 0 0 = 1 : = {0, 1} : 3 (,, ) = + (,, ) = + + (, ) = + (,,, ) = ( + )( + ) + ( + )( + ) + = + = = + + = + = ( + ) + = + ( + ) () = () ( + ) = + + = ( + )( + ) + = = + 0

More information

In plasma catalytic degradation of toluene over different MnO2 polymorphs and study of reaction mechanism

In plasma catalytic degradation of toluene over different MnO2 polymorphs and study of reaction mechanism Chinese Journal of Catalysis 38 (217) 793 84 催化学报 217 年第 38 卷第 5 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article In plasma catalytic degradation

More information

SiO2 supported Au Ni bimetallic catalyst for the selective hydrogenation of acetylene

SiO2 supported Au Ni bimetallic catalyst for the selective hydrogenation of acetylene Chinese Journal of Catalysis 38 (217) 1338 1346 催化学报 217 年第 38 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article SiO2 supported Au Ni bimetallic

More information

La1 xcaxmn1 yalyo3 perovskites as efficient catalysts for two step thermochemical water splitting in conjunction with exceptional hydrogen yields

La1 xcaxmn1 yalyo3 perovskites as efficient catalysts for two step thermochemical water splitting in conjunction with exceptional hydrogen yields Chinese Journal of Catalysis 38 (2017) 1079 1086 催化学报 2017 年第 38 卷第 6 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue on Nanoscience

More information

Selective suppression of toluene formation in solvent free benzyl alcohol oxidation using supported Pd Ni bimetallic nanoparticles

Selective suppression of toluene formation in solvent free benzyl alcohol oxidation using supported Pd Ni bimetallic nanoparticles Chinese Journal of Catalysis 38 (217) 187 1879 催化学报 217 年第 38 卷第 11 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Selective suppression of

More information

Seed induced synthesis of small crystal TS 1 using ammonia as alkali source

Seed induced synthesis of small crystal TS 1 using ammonia as alkali source Chinese Journal of Catalysis 36 (2015) 1928 1935 催化学报 2015 年第 36 卷第 11 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Seed induced synthesis of

More information

Characterization of V2O5/MoO3 composite photocatalysts prepared via electrospinning and their photodegradation activity for dimethyl phthalate

Characterization of V2O5/MoO3 composite photocatalysts prepared via electrospinning and their photodegradation activity for dimethyl phthalate Chinese Journal of Catalysis 36 (2015) 2194 2202 催化学报 2015 年第 36 卷第 12 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue on Photocatalysis)

More information

Visible light responsive carbon decorated p type semiconductor CaFe2O4 nanorod photocatalyst for efficient remediation of organic pollutants

Visible light responsive carbon decorated p type semiconductor CaFe2O4 nanorod photocatalyst for efficient remediation of organic pollutants Chinese Journal of Catalysis 38 (217) 177 1779 催化学报 217 年第 38 卷第 1 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Visible light responsive

More information

Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions

Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions Trans. Nonferrous Met. Soc. China (01) 755 Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions LI Xiao-bin, YAN Li, ZHOU Qiu-sheng, LIU Gui-hua, PENG Zhi-hong School

More information

Resistance to SO2 poisoning of V2O5/TiO2 PILC catalyst for the selective catalytic reduction of NO by NH3

Resistance to SO2 poisoning of V2O5/TiO2 PILC catalyst for the selective catalytic reduction of NO by NH3 Chinese Journal of Catalysis 37 (216) 888 897 催化学报 216 年第 37 卷第 6 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue on Environmental

More information

available at journal homepage:

available at  journal homepage: Chinese Journal of Catalysis 39 (18) 988 996 催化学报 18 年第 39 卷第 5 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Layered double hydroxide like

More information

A new operational medium-range numerical weather forecast system of CHINA. NWPD/NMC/CMA (Beijing,CHINA)

A new operational medium-range numerical weather forecast system of CHINA. NWPD/NMC/CMA (Beijing,CHINA) A new operational medium-range numerical weather forecast system of CHINA NWPD/NMC/CMA (Beijing,CHINA) Organizational Chart of CMA NSMC (National Satellite Meteorological Center) NCC (National Climate

More information

Promotional effects of Er incorporation in CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3

Promotional effects of Er incorporation in CeO2(ZrO2)/TiO2 for selective catalytic reduction of NO by NH3 Chinese Journal of Catalysis 37 (2016) 1521 1529 催化学报 2016 年第 37 卷第 9 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Promotional effects of

More information

Chapter 12: Structures & Properties of Ceramics

Chapter 12: Structures & Properties of Ceramics Chapter 12: Structures & Properties of Ceramics ISSUES TO ADDRESS... Structures of ceramic materials: How do they differ from those of metals? Point defects: How are they different from those in metals?

More information

QTM - QUALITY TOOLS' MANUAL.

QTM - QUALITY TOOLS' MANUAL. 1 2.4.1 Design Of Experiments (DOE) 1. Definition Experimentation is a systematic approach to answer questions and more specifically; how do changes to a system actually affect the quality function or

More information

Preparation of three dimensional interconnected mesoporous anatase TiO2 SiO2 nanocomposites with high photocatalytic activities

Preparation of three dimensional interconnected mesoporous anatase TiO2 SiO2 nanocomposites with high photocatalytic activities Chinese Journal of Catalysis 37 (2016) 846 854 催化学报 2016 年第 37 卷第 6 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue on Environmental

More information

Introduction into defect studies. in ceramic materials(iii) Structure, Defects and Defect Chemistry. Z. Wang. January 18, 2002

Introduction into defect studies. in ceramic materials(iii) Structure, Defects and Defect Chemistry. Z. Wang. January 18, 2002 Introduction into defect studies in ceramic materials(iii) Structure, Defects and Defect Chemistry Z. Wang January 18, 2002 1. Mass, Charge and Site Balance The Schottky reactions for NaCl and MgO, respectively,

More information

La doped Pt/TiO2 as an efficient catalyst for room temperature oxidation of low concentration HCHO

La doped Pt/TiO2 as an efficient catalyst for room temperature oxidation of low concentration HCHO Chinese Journal of Catalysis 38 (217) 39 47 催化学报 217 年第 38 卷第 1 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article La doped Pt/TiO2 as an efficient

More information

Electrical material properties

Electrical material properties Electrical material properties U = I R Ohm s law R = ρ (l/a) ρ resistivity l length σ = 1/ρ σ conductivity A area σ = n q μ n conc. of charge carriers q their charge μ their mobility μ depends on T, defects,

More information

Highly photoreactive TiO2 hollow microspheres with super thermal stability for acetone oxidation

Highly photoreactive TiO2 hollow microspheres with super thermal stability for acetone oxidation Chinese Journal of Catalysis 38 (2017) 2085 2093 催化学报 2017 年第 38 卷第 12 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article (Special Issue on Photocatalysis

More information

Introduction to Engineering Materials ENGR2000. Dr.Coates

Introduction to Engineering Materials ENGR2000. Dr.Coates Introduction to Engineering Materials ENGR2000 Chapter 18: Electrical Properties Dr.Coates 18.2 Ohm s Law V = IR where R is the resistance of the material, V is the voltage and I is the current. l R A

More information

Chapter 12: Electrical Properties. RA l

Chapter 12: Electrical Properties. RA l Charge carriers and conduction: Chapter 12: Electrical Properties Charge carriers include all species capable of transporting electrical charge, including electrons, ions, and electron holes. The latter

More information

Lecture English Term Definition Chinese: Public

Lecture English Term Definition Chinese: Public Lecture English Term Definition Chinese: Public A Convert Change between two forms of measurements 变换 A Equilateral Triangle Triangle with equal sides and angles A FPS Units The American system of measurement.

More information

4. I-V characteristics of electric

4. I-V characteristics of electric KL 4. - characteristics of electric conductors 4.1 ntroduction f an electric conductor is connected to a voltage source with voltage a current is produced. We define resistance being the ratio of the voltage

More information

Concurrent Engineering Pdf Ebook Download >>> DOWNLOAD

Concurrent Engineering Pdf Ebook Download >>> DOWNLOAD 1 / 6 Concurrent Engineering Pdf Ebook Download >>> DOWNLOAD 2 / 6 3 / 6 Rozenfeld, WEversheim, HKroll - Springer.US - 1998 WDuring 2005 年 3 月 1 日 - For.the.journal,.see.Conc urrent.engineering.(journal)verhagen

More information

Riemann s Hypothesis and Conjecture of Birch and Swinnerton-Dyer are False

Riemann s Hypothesis and Conjecture of Birch and Swinnerton-Dyer are False Riemann s Hypothesis and Conjecture of Birch and Swinnerton-yer are False Chun-Xuan Jiang. O. Box 3924, Beijing 854 China jcxuan@sina.com Abstract All eyes are on the Riemann s hypothesis, zeta and L-functions,

More information

Lecture 7: Extrinsic semiconductors - Fermi level

Lecture 7: Extrinsic semiconductors - Fermi level Lecture 7: Extrinsic semiconductors - Fermi level Contents 1 Dopant materials 1 2 E F in extrinsic semiconductors 5 3 Temperature dependence of carrier concentration 6 3.1 Low temperature regime (T < T

More information

Alternative flat coil design for electromagnetic forming using FEM

Alternative flat coil design for electromagnetic forming using FEM Alternative flat coil design for electromagnetic forming using FEM M. AHMED 1, S. K. PANTHI 1, N. RAMAKRISHNAN 2, A. K. JHA 1, A. H. YEGNESWARAN 1, R. DASGUPTA 1, S. AHMED 3 1. Advanced Materials and Processes

More information

Preparation of mesoporous Fe-Cu mixed metal oxide nanopowder as active and stable catalyst for low-temperature CO oxidation

Preparation of mesoporous Fe-Cu mixed metal oxide nanopowder as active and stable catalyst for low-temperature CO oxidation Chinese Journal of Catalysis 36 (215) 1711 1718 催化学报 215 年第 36 卷第 1 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Preparation of mesoporous Fe-Cu

More information

Crystal Properties. MS415 Lec. 2. High performance, high current. ZnO. GaN

Crystal Properties. MS415 Lec. 2. High performance, high current. ZnO. GaN Crystal Properties Crystal Lattices: Periodic arrangement of atoms Repeated unit cells (solid-state) Stuffing atoms into unit cells Determine mechanical & electrical properties High performance, high current

More information

Gauss-Bonnet Theorem on Moduli Spaces. 陆志勤 Zhiqin Lu, UC Irvine

Gauss-Bonnet Theorem on Moduli Spaces. 陆志勤 Zhiqin Lu, UC Irvine Gauss-Bonnet Theorem on Moduli Spaces 陆志勤 Zhiqin Lu, UC Irvine 台大数学科学中心 July 28, 2009 Zhiqin Lu, UC Irvine Gauss-Bonnet Theorem 1/57 Background Calabi-Yau 3-folds are one of the most important objects

More information

Definitions, Closest packing schemes Interstitial sites Other packing schemes Polymorphism (disintegrating buttons) Alloys. Closest packing of coins

Definitions, Closest packing schemes Interstitial sites Other packing schemes Polymorphism (disintegrating buttons) Alloys. Closest packing of coins Definitions, Closest packing schemes Interstitial sites Other packing schemes Polymorphism (disintegrating buttons) Alloys Closest packing of coins AB closest packing of spheres ABC closest packing of

More information

Introduction to Semiconductor Devices

Introduction to Semiconductor Devices Physics 233 Experiment 48 Introduction to Semiconductor Devices References 1. G.W. Neudeck, The PN Junction Diode, Addison-Wesley MA 1989 2. Background notes (Appendix A) 3. Specification sheet for Diode

More information

Effect of methanol concentration on oxygen reduction reaction activity of Pt/C catalysts

Effect of methanol concentration on oxygen reduction reaction activity of Pt/C catalysts Chinese Journal of Catalysis 34 (213) 115 1111 催化学报 213 年第 34 卷第 6 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Effect of methanol concentration

More information

12/10/09. Chapter 18: Electrical Properties. View of an Integrated Circuit. Electrical Conduction ISSUES TO ADDRESS...

12/10/09. Chapter 18: Electrical Properties. View of an Integrated Circuit. Electrical Conduction ISSUES TO ADDRESS... Chapter 18: Electrical Properties ISSUES TO ADDRESS... How are electrical conductance and resistance characterized? What are the physical phenomena that distinguish? For metals, how is affected by and

More information

Two dimensional materials confining single atoms for catalysis

Two dimensional materials confining single atoms for catalysis Chinese Journal of Catalysis 38 (2017) 1443 1453 催化学报 2017 年第 38 卷第 9 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Perspective (Special Issue of

More information

La pietra da altre colline può levigare la giada di questa qui Il Classico dei Versi 可 以 攻 玉

La pietra da altre colline può levigare la giada di questa qui Il Classico dei Versi 可 以 攻 玉 T r e n d s o f H e a l t h c a r e P e r f o r m a n c e E v a l u a t i o n i n C h i n a : a n E c o n o m i c a n d S o c i a l A n a l y s i s A t h e s i s p r e s e n t e d b y H a o L i T o T h

More information

ANALYSIS OF INSULATION OF MATERIAL PROJECT OF DESIGN OF EXPERIMENT

ANALYSIS OF INSULATION OF MATERIAL PROJECT OF DESIGN OF EXPERIMENT ANALYSIS OF INSULATION OF MATERIAL PROJECT OF DESIGN OF EXPERIMENT Group Member: Wang Deyu, Li Dejun, Zhong Haoyuan Xu Shanshan, Li Yaqiong, Yan Li CATALOG 1 Literature Review... 3 2 Executive Summary...

More information

Topics to discuss...

Topics to discuss... MME 467: Ceramics for Advanced Applications Lecture 18 Defects in Ceramics 2 Ref: Barsoum, Fundamentals of Ceramics, Ch6, McGraw-Hill, 2000 Prof. A. K. M. B. Rashid Department of MME, BUET, Dhaka Topics

More information

Lecture 1. OUTLINE Basic Semiconductor Physics. Reading: Chapter 2.1. Semiconductors Intrinsic (undoped) silicon Doping Carrier concentrations

Lecture 1. OUTLINE Basic Semiconductor Physics. Reading: Chapter 2.1. Semiconductors Intrinsic (undoped) silicon Doping Carrier concentrations Lecture 1 OUTLINE Basic Semiconductor Physics Semiconductors Intrinsic (undoped) silicon Doping Carrier concentrations Reading: Chapter 2.1 EE105 Fall 2007 Lecture 1, Slide 1 What is a Semiconductor? Low

More information

tan θ(t) = 5 [3 points] And, we are given that d [1 points] Therefore, the velocity of the plane is dx [4 points] (km/min.) [2 points] (The other way)

tan θ(t) = 5 [3 points] And, we are given that d [1 points] Therefore, the velocity of the plane is dx [4 points] (km/min.) [2 points] (The other way) 1051 微甲 06-10 班期中考解答和評分標準 1. (10%) A plane flies horizontally at an altitude of 5 km and passes directly over a tracking telescope on the ground. When the angle of elevation is π/3, this angle is decreasing

More information

MECHANICS OF MATERIALS

MECHANICS OF MATERIALS CHAPTER 2 MECHANICS OF MATERIALS Ferdinand P. Beer E. Russell Johnston, Jr. John T. DeWolf David F. Mazurek Lecture Notes: J. Walt Oler Texas Tech University Stress and Strain Axial Loading 2.1 An Introduction

More information

Fabrication of a monoclinic/hexagonal junction in WO3 and its enhanced photocatalytic degradation of rhodamine B

Fabrication of a monoclinic/hexagonal junction in WO3 and its enhanced photocatalytic degradation of rhodamine B Cinese Journal of Catalysis 37 (2016) 349 358 催化学报 2016 年第 37 卷第 3 期 www.cjcatal.org available at www.sciencedirect.co journal oepage: www.elsevier.co/locate/cnjc Article (Invited Article fro te Awardee

More information

Electrical Properties

Electrical Properties Electrical Properties Electrical Conduction R Ohm s law V = IR I l Area, A V where I is current (Ampere), V is voltage (Volts) and R is the resistance (Ohms or ) of the conductor Resistivity Resistivity,

More information

CHEM1902/ N-2 November 2014

CHEM1902/ N-2 November 2014 CHEM1902/4 2014-N-2 November 2014 The cubic form of boron nitride (borazon) is the second-hardest material after diamond and it crystallizes with the structure shown below. The large spheres represent

More information

Chapter 4: Bonding in Solids and Electronic Properties. Free electron theory

Chapter 4: Bonding in Solids and Electronic Properties. Free electron theory Chapter 4: Bonding in Solids and Electronic Properties Free electron theory Consider free electrons in a metal an electron gas. regards a metal as a box in which electrons are free to move. assumes nuclei

More information

In situ DRIFTS study of the mechanism of low temperature selective catalytic reduction over manganese iron oxides

In situ DRIFTS study of the mechanism of low temperature selective catalytic reduction over manganese iron oxides Chinese Journal of Catalysis 35 (2014) 294 301 催化学报 2014 年第 35 卷第 3 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article In situ DRIFTS study of the

More information

Lecture 04 Structure of Ceramics 1 Ref: Barsoum, Fundamentals of Ceramics, Ch03, McGraw-Hill, 2000.

Lecture 04 Structure of Ceramics 1 Ref: Barsoum, Fundamentals of Ceramics, Ch03, McGraw-Hill, 2000. MME 467 Ceramics for Advanced Applications Lecture 04 Structure of Ceramics 1 Ref: Barsoum, Fundamentals of Ceramics, Ch03, McGraw-Hill, 2000. Prof. A. K. M. Bazlur Rashid Department of MME, BUET, Dhaka

More information

Solids. properties & structure

Solids. properties & structure Solids properties & structure Determining Crystal Structure crystalline solids have a very regular geometric arrangement of their particles the arrangement of the particles and distances between them is

More information

SEPARATING ARSENIC OXYANIONS FROM NATURAL WATERS FOR OXYGEN ISOTOPE ANALYSIS

SEPARATING ARSENIC OXYANIONS FROM NATURAL WATERS FOR OXYGEN ISOTOPE ANALYSIS SEPARATING ARSENIC OXYANIONS FROM NATURAL WATERS FOR OXYGEN ISOTOPE ANALYSIS Zur Erlangung des akademischen Grades eines DOKTORS DER NATURWISSENSCHAFTEN (Dr. rer.nat.) von der Fakultät für Bauingenieur-,

More information

Synergistic effect of cobalt and copper on a nickel based modified graphite electrode during methanol electro oxidation in NaOH solution

Synergistic effect of cobalt and copper on a nickel based modified graphite electrode during methanol electro oxidation in NaOH solution Chinese Journal of Catalysis 36 (215) 1867 1874 催化学报 215 年第 36 卷第 11 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Synergistic effect of cobalt

More information

A mini review on carbon based metal free electrocatalysts for

A mini review on carbon based metal free electrocatalysts for Chinese Journal of Catalysis 34 (2013) 1986 1991 催化学报 2013 年第 34 卷第 11 期 www.chxb.cn available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Review (Dedicated to Professor Yi

More information

Atomic Arrangement. Primer in Materials Spring

Atomic Arrangement. Primer in Materials Spring Atomic Arrangement Primer in Materials Spring 2017 30.4.2017 1 Levels of atomic arrangements No order In gases, for example the atoms have no order, they are randomly distributed filling the volume to

More information

Ceramics. Ceramic Materials. Ceramics / Introduction. Classifications of Ceramics

Ceramics. Ceramic Materials. Ceramics / Introduction. Classifications of Ceramics Ceramic Materials Outline Structure and Properties of Ceramics Introduction Classifications of Ceramics Crystal Structures Silicate Ceramics Ceramic Phase Diagram Carbon based materials Why study ceramic

More information

Batteries (Electrochemical Power Sources)

Batteries (Electrochemical Power Sources) Batteries (Electrochemical Power Sources) 1. Primary (single-discharge) batteries. => finite quantity of the reactants 2. Secondary or rechargeable batteries => regeneration of the original reactants by

More information

SEMICONDUCTORS. Conductivity lies between conductors and insulators. The flow of charge in a metal results from the

SEMICONDUCTORS. Conductivity lies between conductors and insulators. The flow of charge in a metal results from the SEMICONDUCTORS Conductivity lies between conductors and insulators The flow of charge in a metal results from the movement of electrons Electros are negatively charged particles (q=1.60x10-19 C ) The outermost

More information

Preparation and shape memory properties of TiO 2 /PLCL biodegradable polymer nanocomposites

Preparation and shape memory properties of TiO 2 /PLCL biodegradable polymer nanocomposites Trans. Nonferrous Met. Soc. China 23(2013) 120 127 Preparation and shape memory properties of TiO 2 /PLCL biodegradable polymer nanocomposites Xi-li LU, Xiu-qian LÜ, Jian-yong WANG, Zhi-jie SUN, Yun-xiang

More information