In3+Nb5+双取代钙钛矿型锂快离子导体Li3xLa0.67-xTiO3的研究

以Li3xLa0.67-xTiO3为母体,通过掺杂经高温固相反应制得了一系列新的锂快离子导体材料Li3xLa0.67-xInyTi1-2yNbyO3.利用X射线衍射分析和交流阻抗技术研究该系统的组成结构和电化学性能.结果表明体系合成温度降低,分解电压提高了;在x=0.10,y＜0.050时,合成物为单一的钙钛矿固溶体,y≥0.050时,则存在In2O3杂相;该体系合成物在室温下有较高的电导率,可达5.81×10-4S/cm,活化能在20～30kJ/mol之间.     

PEO-Li1.3Al0.3Ti1.7(PO4)3复合聚合物电解质的制备与电导率研究

将实验室制备的两种烧结型的Li1.3Al0.3Ti1.7(PO4)3盐与PEO/LiClO4复合,制得了PEO-LiClO4-Li1.3Al0.3Ti1.7(PO4)3复合聚合物电解质,测量了298～373K温度范围内的阻抗,得出这种体系的复合聚合物电解质的离子电导率在室温最高值为1.387×10-5S/cm,在373K时可达到1.378×10-3S/cm.     

锂快离子导体Li3-2x(Al1-xTix)2(PO4)3的合成与表征

NASICON型正磷酸盐LiM2(PO4)3(M=Ti,Ge,Zr,Hf)是近来研究得比较深入的锂快离子导体.LiTi2(PO4)3难于烧结得到致密的LiT2(PO4)3陶瓷,且离子电导率很低,在298K时为8.260×10-8 S/cm,613K时为8.241×10-5 S/cm,而当以三价的Al3 离子经传统的固相烧结反应部分取代LiTi2(PO4)3中四价的Ti4 离子后,通过DSC、DTG、电化学阻抗与SEM测试表明,不仅能获得致密度高稳定的产物,而且烧结后得到的锂快离子导体Li3-x(Al1-xTix)2(PO4)3(X=1.0～0.55)体系在室温下的电导率有了巨大的提高.当X=0.85时,组分Li1.3Al0.3Ti1.7(PO4)3离子电导率最大,298K时为1.792×10-6S/cm和613K时为9.210×10-4S/cm.     

新型氧离子导体La1.84R0.16Mo1.7W0.3O8.92（R=Ca^2＋、Sr^2＋、Ba^2＋）的制备及其电性能

以La2Mo1.7W0.3O9为本体,在La位进行碱土金属掺杂,采用溶胶-凝胶方法合成新型氧离子导体La1.84R0.16Mo1.7 W0.3O8.92(R=Ca2 、Sr2 、Ba2 ).应用示差热分析(DTA)、X射线衍射(XRD)、拉曼光谱(Raman)等手段对氧化物进行结构表征,交流阻抗谱测试电性能.结果表明:掺杂改善了本体导电性能的同时,保持了La2Mo1.7W0.3O9抑制La2Mo2O9相变的功能;碱土离子的掺杂,在体系中引入了氧空位,有利于氧离子扩散,提高氧离子导电性,773K时Ba2 掺杂体系的电导率为1.0×10-4S/cm,高于本体的电导率(5.0×10-5/cm).     

CaZr_(1-x)In_xO_(3-α)(x=0,0.05,0.10,0.15)质子导体的电学性能

采用固相反应法在1400℃合成了CaZr1-xInxO3-α(x=0,0.05,0.10,0.15)陶瓷粉体,在空气中1550℃,10 h对材料进行二次烧结.XRD物相分析结果确定合成后的样品中有CaZrO3和微量CaIn2O4存在.实验在600～850℃含水氩气中测量了样品的交流阻抗谱,计算出其电导率随温度变化的规律和电导激活能.在800℃时,CaZr1-xInxO3-α的电导率分别为4.64×10-7 S/cm(x=0)、3.06×10-4 S/cm(x=0.05)、3.89×10-4 S/cm(x=0.10)、3.93×10-4 S/cm(x=0.15).研究结果表明:对CaZrO3掺In能显著提高材料的电导率,降低电导激活能,掺杂量x0.1时,电导率增加变缓,并且电导率随温度的升高而增大.研究得到CaZr1-xInxO3-α的电导率与掺杂量的关系式.     

Al3+、S6+掺杂的矿物锂快离子导体Li1.2+x-yAl0.1+xTi1.9-xSi0.1SyP2.9-yO12系统的合成与表征

以LiTi2(PO4)3为母体,以天然高岭石为起始原料,经高温固相反应制得了一系列新的锂快离子导体Li1.2 x-yAl0.1 xTi1.9-xSi0.1SyP2.9-yO12(以下简称Al-S-Lisicon).X射线粉末衍射分析结果表明在x≤0.30,y＜0.2 x的组成范围内均能得到类似于Nasicon三方结构的相.应用交流阻抗技术测定电导率的结果表明起始组成为x=0.20,y=0.20的合成物电导率最高,室温下为6.01×10-5S/cm,573K时达1.11×10-2S/cm,其在373～573K间的活化能为28.6kJ/mol,分解电压为3.1V.     

矿物锂快离子导体Li1+2xAlxSCyNbyTi2-x-2ySixP3-xO12系统的合成与表征

以LiTi2(PO4)3为母体,天然高岭石为起始原料,经高温固相反应制得了一系列新的锂快离子导体材料Li1+2xA1xScyNbyTi2-x-2ySixP3-xO12(以下简称Sc-Nb-Lisicon).X射线衍射分析表明x=0.1、x=0.2,y≤0.4;x=0.3,y≤0.25的组成范围内能得到类似于Nasicon的三方结构,即空间点群为R3C的合成物.应用交流阻抗技术测试其电导率,结果表明:x=0.1,y=0.3及x=0.2,y=0.15的合成物在室温下有较高的电导率,分别为1.05×10-4S/cm和2.78×10-4S/cm,二者在573K时的电导率可达8.00×10-3S/cm和7.82×10-3S/cm,同时在423～573K具有较低的活化能,分别为31.4kJ/mol和34.8kJ/mol.     

钙钛矿型锂快离子导体Li3xLa0.67-xCryTi1-2yNbyO3系统的研究

以Li3xLn0.67-xTiO3为母体,通过掺杂经高温固相反应制得一系列新的锂快离子导体材料Li3xLa0.67-xCryTi1-2yNbyO3.X射线衍射分析表明x=0.10和y≤0.10的组成范围内能得到钙钛矿型的固溶体.应用交流阻抗技术测试其电导率,结果表明:系统合成物在室温下有较高的体相电导和总电导分别为10-4S/cm和10-5S/cm,其中在x=0.10和y=0.025具有最大值为3.62×10-4S/cm.同时在298～523K具有较低的体相活化能和总活化能,分别约为13～20kJ/mol和35～38kJ/mol.     

锂快离子导体Li1+2x+2yAlxMgyTi2-x-ySixP3-xO12系统的研究

以LiTi2(PO4)3为基以天然高岭石为起始原料,经高温固相反应(～900℃)制得了一系列新的锂快离子导体材料Li1+2x+ 2yAlxMgyTi2-x-ySixP3-xO1 2(以下简称Ti-Mg-Lisicon).系统的合成温度随x和y值的增大而降低.应用交流阻抗技术测定的电导率数据结果表明x=0.1,y=0.1的合成物的室温电导率最好为1.01×10-4S/cm,而400℃时x=0.1,y=0.3的合成物的电导率最大,为2.53×10-2S/cm.XRD分析结果表明在x=0.1,y≤0.8;x=0.2,y≤0.6的组成范围内均能得到空间群为R3c的合成物.     

Zn2+、Ge4+的取代对Li5AlSi2O8的影响

尝试以叶腊石为基体,通过高温固相反应,合成通式为Li5+xAl1-xZnxSi2-2xGe2xO8(x=0.0～1.0)系统锂快离子导体.X射线粉末衍射表明当x≤0.3时体系仍维持原有的Li5AlSi2O8结构(正交晶系);x＞0.5时结构发生明显变化,体系转变成Li6ZnGe2O)8.红外检测显示当x≥0.1红外谱图中出现Li2CO3吸收峰,表明在室温下体系中的Ge4+吸收空气中的CO2而发生分解反应.交流阻抗技术测试交流阻抗表明当温度大于200℃时体系有较高的电导率,最高时为1.11×10-2S/cm(400℃,x=1.0),x≤0.5时离子电导率很低,且不随温度变化.     

Sr_(1-x)La_xCo_(0.3)Ti_(0.3)Fe_(11.4)O_(19)铁氧体微波吸收特性的研究

采用溶胶-凝胶工艺制备了Sr_(1-x)La_xCo_(0.3)Ti_(0.3)Fe_(11.4)O_(19)铁氧体,利用XRD和微波网络矢量分析仪对其相成分和吸收特性进行研究,实验发现:适量的掺杂稀土镧时能够增大吸收频带宽度,改善吸收性能;当x=0.3时,最大吸收可达42.37dB,10dB带宽达2.90GHz,20dB带宽达2.33GHz,这非常有利于作为高频吸波材料。通过对Sr_(0.7)La_(0.3)Co_(0.3)Ti_(0.3)Fe_(11.4)O_(19)铁氧体烧结温度的分析,发现在800℃烧结,晶粒只有40nm左右,吸收性能最好。     

Magnetocaloric Effect in La0.7Cd0.3MnO3, La0.7Ba0.3MnO3, and Nd0.7Sr0.3MnO3

We have based on isothermal magnetization curves to study the magnetocaloric effect (MCE) in fine-grained perovskite manganites of La_0.7Cd_0.3MnO₃ (LCMO), La_0.7Ba_0.3MnO₃ (LBMO), and Nd_0.7Sr_0.3MnO₃ (NSMO) prepared by conventional solid-state reaction. Magnetic measurements were performed on a vibrating sample magnetometer, with a temperature increment of 1.0?K, and the applied field in the range of 0?C1.8?T. Under an applied field of 1.8?T, the maximum magnetic-entropy change obtained for LCMO, LBMO, and NSMO taking place at their Curie temperature are about 2.3, 2.1, and 5.1?J/(kg?K), respectively. The large entropy change in NSMO makes it suitable for magnetic-cooling applications.     

LixCo0.4Ni0.3Mn0.3O2 electrode materials: Electrochemical and structural studies

LiCo_0.4Ni_0.3Mn_0.3O₂ layered oxide in a member of the LiCo_1?2xNi_xMn_xO₂ solid solution between LiCoO₂ and LiNi_0.5Mn_0.5O₂. Compositions from this solid solution have attracted much attention and have been extensively studied as promising cathode candidates to replace the most popular LiCoO₂ cathode material used in the commercial lithium-ion batteries (LiBs). LiCo_0.4Ni_0.3Mn_0.3O₂ positive electrode material was prepared via the combustion method followed by a thermal treatment at 900 °C for 12 h. This material was characterized by a high homogeneity and a granular shape. The Rietveld refinement evidenced that the structure of this compound exhibits no Ni/Li disorder revealing that the LiCo_1?2xNi_xMn_xO₂ system presents the ideal structure for LiBs application when x < 0.4. The electrochemical performances of the LiCo_0.4Ni_0.3Mn_0.3O₂ sample were measured at different current rates in the 2.7–4.5 V potential range. Its discharge capacity reached 178, 161 and 145 mAhg^?1 at C/20, 1C and 2C, respectively. Structural changes in LiCo_0.4Ni_0.3Mn_0.3O₂ upon delithiation were studied using ex situ X-ray diffraction. A continuous solid solution with a rhombohedral symmetry was detected in the whole composition range. This structural stability during the cycling combined with the obtained electrochemical features make this material convenient for the LiBs applications.     

Synthesis,microstructural investigation and compaction behavior of Al0.3CrFeNiCo0.3Si0.4 nanocrystalline high entropy alloy

This research article focused on developing Al_0.3CrFeNiCo_0.3Si_0.4 nanocrystalline high-entropy alloy (HEA) by mechanical alloying. The initial powders mixture was ball milled for 1 hr (HEA-1 h), 5 hr (HEA-5 h), 15 hr (HEA-15 h) and 25 hr (HEA-25 h) at ball to powder mass ratio (BPR) of 15:1 and a speed of 300 rpm. The mechanical alloying time was varied from 1 to 25 hr to ensure the nanocrystalline nature and attainment of steady state in HEA powders. The structure of the developed HEAs was characterized by means of X-ray diffraction (XRD), Laser particle size analyzer (LPSA), and various electron microscopes (TEM and FEGSEM with EDS). HEA-25hr sample exhibited the crystallite size of 13.8 nm with lattice strain of 0.67% obtained from XRD which matched the result by TEM. The formation of a solid solution (SS) with a uniform elemental dispersion was observed with a major BCC stable structure and a minor FCC structure in HEA-25 h sample. The HEA-25 h sample revealed an average particle size of 386.2 nm (89.8% peak intensity) with Polydispersity Index (PDI) value of 0.364 which confirmed the uniform distribution of particles over a narrow range of particle size. The synthesized powders were consolidated to green compacts with a loading rate of 1 mm/min at different compaction pressures (25, 50, 75, 100, 150, 200, 400, 600, 800, 1000, and 1100 MPa) for examining the powder particles packing. Several compaction models (both linear and non-linear) were discussed to establish the density-pressure relationship of developed HEAs. The results revealed that the milling time has influenced the relative density. HEA-1 h sample was exhibited the relative density of 0.76 whereas HEA-25 h sample was produced the relative density of 0.6 indicating more strength and more amount of strain hardening occurs in MAed HEA-25 sample in addition to the entropy effect for the same composition.     

Effect of Particle Size on Magnetic Phase Coexistence in Nanocrystalline La0.4Bi0.3Sr0.3MnO3

Journal of Superconductivity and Novel Magnetism - Magnetic phase coexistence in the substituted perovskite compound, La0.4Bi0.3Sr0.3MnO3, is attributed to the spontaneous moment and a step-like...     

0.3级测力仪标准装置的不确定度评定

本文介绍了0.3级测力仪标准装置检定结果的测量不确定度评定。     

Spin Glass transition on Fe0.6Cr0.1Al0.3 and Fe0.6Ti0.1Al0.3

DC-magnetization measurements on Fe_0.6Cr_0.1Al_0.3 and Fe_0.6Ti_0.1Al_0.3 reveals the disappearance of the wide ferromagnetic state exists in the free doped Fe_0.7Al_0.3 alloy. Our data shows that the spin glass transition temperature for Fe_0.6Cr_0.1Al_0.3 alloy is 38 K and for Fe_0.6Ti_0.1Al_0.3 alloy is 41 K. These values are below 70 K which is the spin transition temperature of the Fe_0.7Al_0.3 alloy. This is attributed to the paramagnetic nature of the metals Cr and Ti.     

Thermodynamic properties of the superconductorsBaPb 0.7 Bi 0.3 O 3 andBa 0.7 K 0.3 BiO 3 using Eliashberg theory

We present results of a thermodynamic analysis for the superconductors compounds BaPb_0.7Bi_0.3O₃ and Ba_0.7K_0.3BiO₃. The physical quantities are calculated making use of the Eliashberg theory and the electron-phonon spectra ²()F() as calculated by Shirai et al. For the superconductor BaPb_0.7Bi_0.3O₃, several models of the ²()F() were studied looking for a better agreement with experimental data. The best fit is achieved with a simple constant scaling (C = 1.25) of the Shirai's spectra. The functional derivative of the deviation function D(t) with respect to changes in ²()F() is also calculated.     

热压法制备0.3PZN-0.7PZT压电陶瓷研究

研究了热压法制备０．３ＰＺＮ－０．７ＰＺＴ系压电陶瓷过程中,铅含量以及热压和退火工艺对材料性能的影响．实验结果表明,适当降低铅含量、提高退火温度和退火时间可得到性能优良的压电陶瓷．制得的压电陶瓷密度接近理论密度,电性能指标为： ｄ_３３＝７１５ ｐＣ／Ｎ, Ｋ_ｐ＝０．６５, ｔｇδ＝２．９％, ε_ｒ＝３４５７, Ｑ_ｍ＝５０．１．