镧掺杂钙锰氧体/聚吡咯复合物的制备、表征及其电化学性能

采用甘氨酸-硝酸盐燃烧法和溶液原位复合技术分别制备了镧掺杂钙锰氧体(La_{1- x} Ca_x Mn_{0. 7}Co_{0. 3}O₃, x = 1. 0, 0. 9, 0. 8 , 0. 7, 0.6) 粉末及其聚吡咯( PPy) 相对质量分数为60 %和80 %的钙锰氧体/ 聚吡咯复合物微粒La_{0. 3}Ca_0.7Mn_{0. 7}Co_{0. 3}O₃/PPy。借助FTIR、XRD、SEM 和电化学测试等分析手段表征了钙锰氧体粉末及其复合材料的结构、形貌和电化学性能。结果表明, 复合材料中包覆的聚吡咯外层和复合氧化物之间存在相互作用, PPy 减少了纳米颗粒的团聚现象,La_{0. 3}Ca_0.7Mn_{0. 7}Co_{0. 3}O₃和La_{0. 3}Ca_0.7Mn_0.7Co_{0. 3}O₃/PPy的粒径分别为46. 2 nm 和43. 5 nm , 并且复合物的氧化还原峰电流随吡咯含量的增加而变大。      

TiN/聚吡咯纳米复合材料的制备及表征

采用氨解法制备了纳米氮化钛(TiN)粉体,对纳米TiN粉体进行表面改性,使其均匀分散到吡咯单体中.采用原位聚合法制备了TiN/聚吡咯(PPy)纳米复合材料.对合成的复合材料用X射线衍射(XRD)、透射电镜(TEM)、傅立叶变换红外光谱(FT-IR)、四探针测试仪等方法进行了表征与检测.结果表明:PPy成功地包覆在TiN纳米颗粒表面,形成了纳米TiN/PPy复合材料.复合材料具有优良的电性能.     

石墨烯/聚吡咯复合材料制备及应用研究进展

具有独特二维纳米结构的石墨烯可为电子转移提供通道,使其复合材料具有优良的电容性能。聚吡咯(PPy)因具有超电容性能、聚合电位低和空气稳定性好等优点,常作为理想型电极材料。综述了原位化学氧化聚合法和电化学沉积法2种石墨烯/PPy复合材料的制备方法,以及石墨烯/PPy复合材料在超级电容器、微波吸收、燃料电池催化剂和传感器等电化学方面的应用现状,并展望了石墨烯/PPy复合材料的未来发展方向。     

聚吡咯／木单板导电复合材料的制备与表征

以FeCl3为氧化剂和掺杂剂，采用化学氧化原位吸附聚合法制备了聚吡咯／木单板复合材料。探讨了制备条件对表面电阻率和吸聚率的影响，以及获得的较优的制备条件。利用红外光谱（FT-IR）、X射线衍射（XRD）和扫描电镜（SEM）表征了材料的组成、结构和形貌。结果表明，制备条件为：单板室温吸附吡咯单体的时间30min，FeCl3浓度0．75mol／L，聚合反应时间30min，反应温度25℃。复合材料的表面电阻率可这15．53Ω／cm^2。复合材料中木单板表面吸附聚合了无定形的掺杂态的聚吡咯，聚吡咯排列紧密，有少量孔隙，无明显的方向性，且与木材表面有一定的相互作用。     

片状聚吡咯/氧化石墨烯复合材料的制备及电化学性能

通过原位聚合在低温条件下(-10℃)制备具有片状微结构的聚吡咯(PPy)/氧化石墨烯(GO)复合材料,利用傅里叶红外光谱仪(FT-IR),扫描电子显微镜(SEM)对复合材料进行结构表征的基础上,利用循环伏安(CV)、恒流充放电(GC)、电化学阻抗技术(EIS)测试复合材料的电化学性能。FT-IR结果表明复合材料中GO与PPy存在相互作用;SEM结果表明复合材料显示为亚微米片状结构形貌;CV、GC、EIS电化学分析表明,与纯聚吡咯及氧化石墨烯相比,复合材料显示出优越的电容特性。当电流密度保持在1 A/g时,复合材料的比电容可达319 F/g,比GO(9 F/g)和PPy(167 F/g)的比电容都要高,该复合材料可用作潜在的超级电容器电极材料。     

聚吡咯/蒙脱土复合材料的制备与性能

以水为介质，FeCl3为氧化剂，用化学氧化法制备了聚吡咯／蒙脱土复合材料。研究了反应温度、反应时间、蒙脱土和氧化剂用量、掺杂剂种类及用量等因素对聚合反应的影响，确定了最佳反应条件。同时考察了材料的导电稳定性。结果表明，温度是此反应最主要的影响因素，O℃时制备的复合材料的电导率已迭50．0S／cm。其导电稳定性也优于其它同类材料。50d内，低温产物电导率下降不到10％。     

TiO_2-聚吡咯复合材料的制备及光催化性能

采用原位氧化聚合法制备TiO2-聚吡咯复合材料,研究吡咯与TiO2配比对TiO2-聚吡咯复合材料在紫外光和太阳光下光催化降解甲基橙的影响,利用傅里叶红外光谱仪、X射线衍射仪、紫外-可见光谱仪对样品进行表征。结果表明,TiO2-聚吡咯复合材料与纯聚吡咯相比,聚吡咯本征态特征峰和C─N伸缩振动峰峰值都向高波数偏移,TiO2和聚吡咯的复合并不是单纯的物理复合,而是产生了化学作用力;通过改变吡咯的添加量,可以控制聚吡咯在TiO2粉体表面的包覆量,聚吡咯的包覆对TiO2的晶型没有影响;聚吡咯对TiO2的包覆可降低TiO2的禁带宽度至2.90 eV,使TiO2-聚吡咯复合材料可吸收的波长范围拓宽到可见光区,提高复合材料在可见光下的光催化能力;适量的聚吡咯包覆可以提高TiO2-聚吡咯复合材料的光催化活性,以紫外灯作为光源催化降解甲基橙,当吡咯包覆质量分数为0.06时,复合材料的电子-空穴对分离效果最好;以太阳光作为光源催化降解甲基橙,当吡咯包覆质量分数为0.04时,复合材料的光谱拓展效果最好。     

聚吡咯/碳纤维纸电热复合材料的制备及性能

在碳纤维纸（CPP）上采用气相聚合法使吡咯单体发生聚合生成聚吡咯（PPY）,制备聚吡咯/碳纤维（PPY/CF）纸导电发热复合材料。通过FTIR、SEM、XRD对PPY/CF纸复合材料进行测试分析,并探究了CPP中CF的最佳质量分数及FeCl₃的最优溶度,研究了PPY/CF纸复合材料的力学性能和电热性能。结果表明,成功制备了PPY/CF纸复合材料,且PPY主要附着在芳纶浆粕上;采用CF质量分数为10 wt%的CPP且FeCl₃浓度为1.2 mol/L时,制备的PPY/CF纸复合材料具有最低的电阻率,为0.139 Ω·cm;PPY/CF纸复合材料与CPP相比不仅力学性能大幅提高,而且在低电压下,PPY/CF纸复合材料具有导电性能稳定、发热效果显著、热稳定性好等优点。      

织物增强聚吡咯导电复合材料的制备及特性

利用气相反应可以快速简单地制备织物增强聚吡咯复合材料，在２．３ｗｔ％聚吡咯含一下复合材料具有优良的导电性。由于气相反应合成的聚吡咯是附在纤维表面的薄层，因此在室温条件下材料具有较好的导电稳定性。     

Fe3O4/ 聚吡咯复合材料的制备及表征

以化学沉淀法制备Fe₃O₄ 纳米粒子, 采用乙醇对Fe₃O₄ 纳米粒子表面进行处理, 使其表面有机化, 然后通过乳液原位复合制备Fe₃O₄ / 聚吡咯复合材料。利用TEM, XPS, 四探针测试仪和震荡磁力计对其进行表征和检测。结果表明: 经醇处理的Fe₃O₄ 纳米粒子的分散性得到明显改善, Fe₃O₄ 纳米粒子被包覆在聚吡咯层内, 包覆层厚度为10 nm 左右, 复合材料具有优良的电性能和磁性能, 电导率e= 7. 69 s/ cm～13. 6 s/ cm, 饱和磁强度M_s= 12. 06 emu/ g～24. 38 emu/ g, 矫顽力H_c= 11 Oe～41 Oe。其环境稳定性明显优于纯聚吡咯。      

X-ray Photoelectron Spectra of La0.7Ca0.3MnO3 and La0.7Ca0.3Mn0.97Cu0.03O3 Perovskite Oxides

X-ray photoelectron spectroscopy was used to identify the oxidation states of cations in La_0.7Ca_0.3MnO₃ and La_0.7Ca_0.3Mn_0.97Cu_0.03O₃ perovskite oxides, to determine the surface composition of the samples, and to assess the effect of the Cu dopant on the electronic spectrum of the material. The binding energies of the La 4d, Ca 2p, Mn 2p, and O 1s core levels were determined, and the effect of the Cu dopant on the shape of the La 4d and O 1s peaks was analyzed.     

Electro-magnetic transport behavior of La0.7Ca0.3MnO3/SnO2 composites

The composites of (1 ? x)La_0.7Ca_0.3MnO₃ (LCMO) + xSnO₂ (x = 0.01, 0.05, 0.10, 0.30, 0.50, 0.60, 0.65 and 0.70) were synthesized by conventional solid-state reaction method. The results of X-ray diffraction (XRD) and scanning electronic microscopy (SEM) indicate that SnO₂ and LCMO coexist in the composites and SnO₂ mainly segregates at the grain boundaries of LCMO, which are in accordance with the results of the magnetic measurements. The detailed electrical characterizations for all the samples showed that a new metal–insulator (M–I) transition temperature (T_P2) appeared at a lower temperature compared with the intrinsic metal–insulator (M–I) transition temperature (T_P1) when x < 0.50 (T_P1 > T_P2). When x > 0.50, T_P1 disappeared, leaving only T_P2. The resistivity percolation threshold of the composites occurred at x = 0.60. Corresponding to the two M–I transition peaks, the curves of magnetoresistance against temperature also showed two peaks for all composites. These phenomena can be explained by the segregation of a new phase related to SnO₂ at the grain boundaries or surfaces of the LCMO grains.     

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.     

Structure and magnetoelectric properties of Gd-doped La0.7Ca0.3MnO3 polycrystalline ceramics

Journal of Materials Science: Materials in Electronics - The temperature coefficient of resistance (TCR) and magnetoresistive (MR) properties of materials have a large impact on the performance of...     

Low-field magnetoresistance in La0.7Sr0.3MnO3/BaTiO3 composites

A manganite composite series of (1 ? x)La_0.7Sr_0.3MnO₃/xBaTiO₃ (x = 0, 0.06, 0.12, and 0.18) has been fabricated by solid-state reaction combined with a high-energy mechanical milling method. Experimental results revealed that the insulator–metal transition temperature was shifted towards lower temperatures, and resistivity increases with increasing BaTiO₃ content in (1 ? x)La_0.7Sr_0.3MnO₃/xBaTiO₃. Meanwhile, the ferromagnetic–paramagnetic transition temperature was almost unchanged. The increase in magnetoresistance was observed in the all composites at whole measurement temperatures under an applied magnetic field of 3 kOe. Here, temperature dependences of magnetoresistance display a Curie–Weiss law-like behavior. The nature of this phenomenon is explained in detail.     

Photoelectric properties of n-TiO2/p-Co0.7Ni0.3O heterostructures

The main photoelectric parameters of n-TiO₂/p-Co_0.7Ni_0.3O film heterostructures obtained by sequential sputtering of corresponding metal targets in oxidizing atmosphere have been determined. The heterostructures are photosensitive in a wavelength range of 225–385 nm and exhibit no photoresponse in the visible spectral range. The proposed structures can be used for creating photodetectors with high spectral selectivity.     

La0.7Sr0.3FeO3-Sm0.2Ce0.8O2复合阴极制备及性能研究

采用固相反应法(SSR)和硝酸盐-甘氨酸燃烧法(GNP)合成La0.7Sr0.3FeO3(LSF)粉体,用于制备中温固体氧化物燃料电池的复合阴极LSF-Sm0.2Ce0.8O2(SDC).用交流阻抗谱研究复合阴极的组成、烧结温度、起始粉体性质等因素对电极界面比电阻的影响.结果表明,在LSF中加入适当比例的SDC可明显提高电极的性能.当SDC的加入量达到其渗流阀值(～50%,质量分数)时,在700℃复合阴极的界面比阻抗约为0.2 Ω·cm2,大约为纯LSF的十分之一.电极性能的明显提高的原因是电极离子电导率的提高、CeO2的本征催化性能以及电极三相线密度的增大.     

La0.7Mg0.3Ni2.65Co0.75-xMn0.1Six储氢电极合金的结构和电化学性能

系统研究了Si部分替代Co对La0.7Mg0.3Ni2.65Co0.75Mn0.1储氢电极合金结构和电化学性能的影响。XRD结果显示,随着Si替代量的增加,合金中(La,Mg)Ni3相的丰度逐渐降低,而LaNi5相的丰度逐渐增加,且含Si合金中出现了La2Ni7相。电化学测试表明,Si部分替代Co降低了合金的放电容量,但显著提高了其循环稳定性,改善了其高倍率放电性能。其中Si替代量x=0.15时合金的综合性能较好,合金最大放电容量323mAh/g,75次循环后的容量保持率约为71.9%,1250mA/g电流放电时的HRD可达55%。