Structure and electrical properties of （1-x）BaTiO3W（x）La2/3- Srl/3Mn03 composites

Liquid-phase sintering method was used to prepare BaTiO3 powders and the structure and electrical properties of (1-x)BaTiO3+(x)La2/3Sr1/3MnO3 (LSMO) composites ...     

Low-field magnetoresistance of (1-x)La_(0.6)Dy_(0.1)Sr_(0.3)MnO_3/0.5x (Sb_2O_3) composite system under different sintering temperatures of matrix

A series of (1-x)La0.6Dy0.1Sr0.3MnO3/0.5x(Sb2O3)(x=0.15) samples were prepared by the solid-state reaction method, and the influence of sintering temperature of the matrix on low-field magnetoresistance of (1-x)La0.6Dy0.1Sr0.3MnO3/0.5x (Sb2O3) was studied through the measurements of X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) image, resistivity-temperature (ρ-T) curves, and magnetoresistance-temperature (MR-T) curves. The results indicate that for the samples with low sintering temp...     

Emissivity of La1-xSrxMnO3/acrylic Resin Thermal Control Coating

Thermal control coatings were fabricated by mixing of La1-xSrxMnO3(LSMO)powder and acrylic resin and brushed on Al alloy substrate.The powders of La0.7Sr0.3MnO3 and La0.8Sr0.2MnO3 were prepared using sol-gel method.XRD results reveal the phase structure of LSMO powders are perovskite.The transition temperature from metal to insulator of La0.7Sr0.3MnO3 and La0.8Sr0.2MnO3 are 300 and 275 K,respectively.The emissivity evolution with temperature of the coatings was measured.For La0.7Sr0.3MnO3/acrylic resin coating,the emissivity increases from 0.56 to 0.88,and for La0.7Sr0.3MnO3/acrylic resin coating from 0.50 to 0.90.     

Effect of second introduced phase on magnetotransport properties of La2/3Sr1/3MnO3/0.33(CuO, ZnO, Al2O3) composites

The structure, magnetic and magnetotransport properties of La2/3Sr1/3MnO3(LSMO)/0.33(CuO, ZnO, Al2O3) composites were investigated to explore the role of second introduced phase. The microstructural analysis shows two kinds of grain boundaries: LSMO/LSMO and LSMO/second phase/LSMO. Two maximal resistivities appear in LSMO/0.33CuO and LSMO/0.33ZnO composites while the resistivity of LSMO/0.33Al2O3 decreases monotonically with increasing the temperature from 200 K to 400 K. Moreover, the temperature dependence of magnetoresistance(MR) of LSMO/0.33Al2O3 that decreases monotonically with increasing the temperature is different from that of LSMO/0.33CuO and LSMO/0.33ZnO. A developed two-channel model consisting of scattering model and tunneling model was proposed to fit the resistivity-temperature curves of these composites. The role of second introduced phase and the magnetotransport mechanism of these composites were elucidated.     

Effects of ferrites on magnetic transport properties in La2/3Sr1/3MnO3/ferrites composites

Effects of soft-magnetic MnZn ferrite (Mn0.5Zn0.5Fe2O4, MZF) and hard-magnetic Ba ferrite (BaO·6Fe2O3, BaM) on the structure and magnetic transport properties of [La2/3Sr1/3MnO3] (LSMO)/(x) [ferrites] (ferrites=MZF, BaM) composites have been investigated. It was found that the inclusion of MZF phase reduces magnetization and ferromagnetic-paramagnetic transition temperature (Tc) of the composites. With increasing the content of the dopants, the high-temperature magnetoresistance (MR) decreases, whereas low-...     

Si(100)衬底上(110)取向La_(2/3)Sr_(1/3)MnO_3薄膜的制备与性能

用脉冲激光沉积法在Si(100)衬底上制备了(110)择优取向的La2/3Sr1/3MnO3薄膜,研究了环境氧压对薄膜结晶度、取向、表面形貌和微结构的影响。结果表明:10Pa氧压下沉积的薄膜具有高结晶度的(110)择优取向,晶粒分布均匀,晶粒分布均匀,表面均方根粗糙度Rrms为1.35 nm。与无明显择优取向的薄膜相比,(110)择优取向的La2/3Sr1/3MnO3薄膜具有较高的饱和磁化强度(Ms)、金属-绝缘体相变温度(TM-I)和较低的电阻率(ρ)。     

Mo(Si_(1-x)Al_x)_2/Al_2O_3复合材料的制备与强韧化

以Mo、Al、Si和Mo O_34种粉末为原料,通过燃烧合成和真空热压烧结工艺原位制备了(Si_(1-x)Al_x)_2/Al_2O_3复合材料,分析了其燃烧模式、产物相结构、微观组织和力学性能。结果表明:添加Al之后坯体的燃烧合成反应更加剧烈,燃烧模式由螺旋模式转入混沌模式。随着合金化Al含量的增加,基体相结构由C11_b型Mo Si_2转变为C40型Mo(Si,Al)_2,并且在所有复合材料中都可以鉴别出Al_2O_3衍射峰,表明通过燃烧合成技术原位制备了Mo(Si_(1-x)Al_x)_2/Al_2O_3复合材料。复合材料的断裂韧性和抗弯强度最高分别达到4.25 MPa·m~(1/2)和346 MPa,比纯Mo Si_2提高了39%和60%。复合材料的强韧化机制主要有Al合金化强韧化、Al_2O_3第二相颗粒弥散强韧化、玻璃相的消除以及断裂方式的转变。     

La-（Ca-Ba-Sr）-Mn-O锰氧化物高低温输运特性

用固相反应烧结法制备了多晶体材料La2/3Ca1／3MnO3(LCMO)，La2／3(Ca0.5Ba0.5)1/3MnO3(LCBMO)、La2，3Ba1/3MnO3(LBMO)，La2／3(Sr0.5Ba0.5)1/3MnO3(LSBMO)和La2/3Sr1／3MnO3(LSMO)，测量了它们在77K～800K的电阻和磁电阻特性。实验发现，通过一定的工艺技术制备出的CMR材料有强烈的相界效应，在低温下有大的磁电阻，且在Tc附近存在明显的从金属态向半导体态的转变：用自旋极化电子隧道效应和靠近居里点逾渗模型较好地解释了电阻和磁电阻行为：用非绝热小极化子跃迁模型对高温的电阻特性进行拟合处理，得到了激活能；同时发现退火处理对样品的电阻率有重要的影响。     

La1/3Sr2/3Mn1-xFexO3(x=0,0.05)中电荷有序现象的超声研究

系统研究了La1／3Sr2／3Mn1-xFexO3(x=0，0．05)单相多晶样品在20--300K温区内的电荷输运性质和超声特性，结果表明，La1／3Sr2／3MnO3样品在235K存在明显的电荷有序现象，但是极少量的Fe取代Mn就会有效地抑制电荷有序现象的发生，伴随电荷有序现象的发生声速出现极大的软化，其相对变化超过5％，这表明La1／3Sr2／3Mn1-xFexO3中存在剧烈的电-声子相互作用，分析指出该电-声子耦合主要起源于Jahn-Teller效应。     

颗粒尺寸对多晶La2／3Ca1／3Mn1-xCuxO3低场磁电阻的影响

采用溶胶-凝胶法制备了不同颗粒尺寸的La2/3Ca1/33Mn1-xCuxO3(x=0.04)系列试样。X射线衍射实验说明Cu掺杂和不同温度烧结没有改变晶体的结构。电阻-温度实验曲线表明，随颗粒尺寸的减少，半导体-金属转变温度（Tp）向低温方向移动。磁电阻曲线显示，随颗粒尺寸的减少，与颗粒晶界有关的磁电阻在25K恒温、0.4T低场下由25%增加到了51%。实验结果表明，在La2/3Ca1/3MnO3中少量Cu掺杂和小颗粒尺寸可以实质性地提高与颗粒晶界有关的低场磁电阻效应。     

Si4+和F-掺杂对LiNi1/3Co1/3Mn1/3O2结构和电化学性能的影响

以Li2CO3、NiO、Co2O3、MnO2、LiF和SiO2为原料,采用机械力活化固相法制备了Si4+和F-掺杂的锂离子电池正极材料LiNi1/3Co 1/3Mn1/3O2.通过X射线衍射(XRD)、扫描电镜(SEM)和电化学性能测试等技术研究了LiNi1/3Co1/3Mn1/3O2的结构特征、形貌及电化学性能等.结...     

Fabrication and performance of La0.8Sr0.2MnO3/YSZ graded composite cathodes for SOFC

The performance of multi-layer (1-x)La0.8Sr0.2MnO3/xYSZ graded composite cathodes was studied as electrode materials for intermediate solid oxide fuel cells (SOFC). The thermal expansion coefficient, electrical conductivity, and electrochemical performance of multi-layer composite cathodes were investigated. The thermal expansion coefficient and electrical conductivity decreased with the increase in YSZ content. The (1-x)La0.8Sr0.2MnO3/xYSZ composite cathode greatly increased the length of the active triple phase boundary line (TPBL) among electrode, electrolyte, and gas phase, leading to a decrease in polarization resistance and an increase in polarization current density. The polarization current density of the triple-layer graded composite cathode (0.77 A/cm2) was the highest and that of the monolayer cathode (0.13 A/cm2) was the lowest. The polarization resistance (Rp) of the triple-layer graded composite cathode was only 0.182Ω·cm2 and that of the monolayer composite cathode was 0.323Ω·cm2. The power density of the triple-layer graded composite cathode was the highest and that of the monolayer composite cathode was the lowest. The triple-layer graded composite cathode had superior performance.     

Preparation and magnetic properties of nanosized （La0. 47Gd0. 2 ） Sr0. 33 MnO3

1INTRODUCTION Themagneticpropertyandcrystalstructureof perovskite typelanthanummanganeseoxideswere firststudiedbyJonkerandVanSantenin1950[1].Thesematerialswereofconsiderableinterestinthe lastdecadeduetotheircolossalmagnetoresistance(CMR)effect[24].Recentlyaseriesofhole dopedperovskitemanganeseoxideswerereportedtodis playalargemagnetocaloriceffect(MCE)inthevic inityoftheferromagneticCurietemperature(Tc)[516],whichmaybeexploitedtobeappliedin magneticrefrigeratorandheatpumps[17].Idealmag…     

La0.7Sr0.3MnO3和ZnO异质结的量子铁磁自旋特性

采用脉冲激光沉积方法制备La0.7Sr0.3MnO3/ZnO异质结,并对其量子铁磁自旋行为进行研究。发现掺杂浓度可有效调整长程的电子自旋和轨道的相互作用,以及短程小极化子的相互作用程度。LSMO/ZnO异质结构可对能带进行有效剪裁。XRD结果表明,所制样品具有良好的晶格外延特性。伏安特性和阻温曲线显示异质结具有半金属光导特性。在激光光场和磁场下测试La0.7Sr0.3MnO3/ZnO异质结量子铁磁自旋磁阻及光阻。结果发现,样品x=0.3在Tp=250K发生金属绝缘体相变而呈现半金属特性,在Tc=175K温度发生顺磁到反铁磁相变。连续激光下低于峰值温度220K和脉冲激光下低于175K区域激光光场导致光致退磁,光阻增大,在大于峰值温度Tp的高温区出现光阻降低。研究表明,在光场下La0.7Sr0.3MnO3/ZnO异质结特性受界面电子自旋取向和载流子浓度调控,态密度以及自旋轨道作用会导致光致阻抗变化,这些影响与LSMO/ZnO异质结的极化和界面应力所产生的界面态缺陷结构有关。     

iLaAlO3、MgO和SrTiO3衬底上的La0.7Sr0.3MnO3薄膜输运和光诱导特性研究

利用溶胶-凝胶(Sol-gel)法制备了La0.7Sr0.3MnO3(LSMO)靶材,并采用脉冲激光沉积(PLD)的方法在LaAlO3(100)、MgO(100)和SrTiO3(100)衬底上沉积了外延薄膜,研究了衬底与薄膜之间的晶格不匹配度对LSMO薄膜输运和光诱导特性的影响.结果表明:随着晶格不匹配度(考虑符号)的增加,薄膜的相变温度升高,而电阻率和光电导△ρ值则减小.在低温金属相,光诱导致使电阻率降低;高温绝缘相光诱导则使得电阻率升高,在MgO和SrTiO3衬底上薄膜的光电导△ρ具有极大值和极小值,分析表明这一现象的出现可归结于双交换作用和极化子效应.     

LiNbO3掺杂(Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3-BaTiO3无铅压电陶瓷的压电和铁电性能研究

用传统的固相反应法将LiNbO3(LN)加入(Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3-BaTiO3制得无铅压电陶瓷。研究了该复合体系的压电和铁电性能,着重研究加入LiNbO3对0.852BNT-0.110BKT-0.038BT这一组分的相结构和电性能影响。加LN形成的材料结构分析(XRD)表明,LiNbO3能完全固溶入钙钛矿结构。加入0.05LN导致弥散相变,材料由四方相和菱方相两相共存转变为伪立方相,电滞回线呈现顺电相的特征。加入0.02LN形成的四元系电性能最佳:压电常数d33=245pC/N,机电耦合系数kp=0.20,kt=0.495,室温介电常数εr=1502,剩余极化强度Pr=26μC/cm2。在此基础上,研究了复合LN对去极化温度Td的作用,结果表明,引入LN会降低这一体系的去极化温度。     

La_xSr_(1-x)TiO_3氧化物热电材料的制备与电传输性能

利用溶胶凝胶(sol-gel)法和放电等离子烧结(SPS)制备了单相的钙钛矿结构La_xSr_(1-x)TiO_3 (0≤x≤0.15)块体材料,与传统的固相反应法相比,烧结温度大幅降低.在室温至679 K的温度范围内测量了La_xSr_(1-x)TiO_3 (0≤x≤0.15)的Seebeck系数和电导率,确定了最佳La掺杂量x=0.08.La_0.08Sr_0.92TiO_3在679 K时,最大功率因子PF=2.95 μWm~(-1)·K~(-2),随温度升高,PF增大趋势明显,表明在高温环境中可具有更大的PF.     

钛酸铜钙/钛酸钙复合陶瓷的制备和介电性能

以CaCO_3、TiO_2、CuO为原料,采用两种工艺途径制备了(1-x)CCTO-xCTO(0≤x≤1)复合陶瓷材料.采用X射线衍射仪、扫描电子显微镜、阻抗分析仪对(1-x)CCTO-xCTO复相陶瓷的相组成、显微结构特征和介电性能进行了研究,发现不同工艺途径制备的(1-x)CCTO-xCTO复合陶瓷的显微结构略有差异,但介电性能基本相同,表明两种工艺途径制备的陶瓷中CCTO和CTO具有相似的连接情况.此外,还发现2/8CCTO-6/8CTO复合陶瓷在室温和1 kHz频率时,材料的介电常数ε接近1500,且介电损耗tgδ小于0.08.     

Li1+x(Fey/2Niy/2Mn1-y)1-xO2正极材料的合成及电化学性能

采用低温共沉淀-水热-煅烧法合成了锂离子电池Fe-Ni-Mn体系正极材料Li1+x(Fey/2Niy/2Mn1-y)1-xO2,并用XRD、SEM、ICP光谱和电化学性能测试对材料进行了表征.XRD测试和ICP分析表明,Fe、Ni取代Li2MnO3中的部分Mn,形成很好的固溶结构yLiFe1/2Ni1/2O2-(1-y)Li2MnO3 (y=0.l,0.2,0.3,0.4,0.5).SEM测试表明,取代量y不同,材料的表观形貌有所不同,y=0.4时材料的颗粒粒径均匀、较小,呈类球形结构.电化学性能测试表明,当y=0.4时,循环稳定性最好,充放电50次后放电比容量仍可维持在195.0 mAh/g,放电中值电压为3.5 V,y=0.4时样品在大倍率放电下的电化学性能表现良好.     

High-pressure sintering and magnetic properties of Fe86Zr11-xNbxB3 （x=5.5, 6） amorphous alloys

1 INTRODUCTION Fe-based nanocrystalline soft magnetic alloys become the focus in the world because of their ex- cellent soft magnetic properties and high saturation induction.In engineering applications , soft mag- netic alloys are usually used in bulk form with complex shape . However , nanocrystalline soft magnetic alloys in engineering applications are pre- pared through the crystallization of amorphous al- loy which is controlled by melt spinning, accord- ingly the shape and size of th…