Nd扩渗BaTiO_3陶瓷的电性能与XPS研究

采用气相法对钛酸钡陶瓷扩渗Nd元素,经Nd扩渗BaTiO3陶瓷的电性能发生了十分显著的变化。通过正交实验,确定了最佳扩渗条件,当Nd的浓度为2%,扩渗时间为4h,扩渗温度为860℃时,BaTiO3陶瓷的导电性最好,其室温电阻率从4 3×109Ω·m下降为37 45Ω·m,而且随着温度升高,交流电导逐渐增大,导电性更强。Nd扩渗使BaTiO3陶瓷的介电常数增加,而介电损耗降低,BaTiO3陶瓷的介电性能得到了显著改善。经Nd扩渗BaTiO3陶瓷的介电常数随着温度的变化呈明显的PTC效应,其居里温度降低为118 1℃。经XPS测试分析,给出了Nd扩渗BaTiO3陶瓷体系中各元素结合能位置的峰值,并表明Nd扩渗BaTiO3陶瓷中Nd,Ba,Ti都存在变价,因而导致了BaTiO3陶瓷导电性的增强。     

α、β、γ、δ-四(4-三甲氨基苯基)卟啉与钌(Ⅲ)显色反应的研究

本文研究了α、β、γ、δ-四(4-三甲氨基苯基)卟啉(简称TAPP)和钌的显色反应。其最大的吸收波长位于436nm,表观摩尔吸光系数为5。25×10~5L·mol~(-1)·cm~(-1),钉的浓度在0～2.5μg/10ml范围内服从比尔定律,络合物的组成比为Ru:TAPP=1:1。该法用于合成矿样分析,结果满意。     

钐和钆对K10H3[Dy(SiW4Mo7O39)2]配合物的化学热扩渗及其导电性的研究

报道了Sm,Gd通过固 气界面反应对K10H3[Dy(SiW4Mo7O39)2]配合物的稀土多元渗。经ICP,IR测试表明:微量Sm,Gd可渗入到杂多配合物K10H3[Dy(SiW4Mo7O39)2]体相,XPS能谱分析证实了稀土元素的存在并与化合物有键合作用。采用四电极法对扩渗前后试样进行了导电性能的测定,扩渗后试样的导电率提高了0 9356×104倍。     

Nd2O3添加量对BaTiO3陶瓷介电性能的影响

BaTiO₃ ceramics doped with Nd₂O₃(the additive content was respectively 0.001,0.002,0.003,0.005,0.01,0.03mol)were prepared by Sol-Gel method. Effects of Nd₂O₃ contents on the dielectric constant (ε), the dielectric loss (tanδ) ,the Curie-temperature (T_C) and the resistivity (ρ) of BaTiO₃ ceramic were studied. When Nd₂O₃ content was 0.001mol and 0.002mol, the dielectric constant was increased obviously, but the dielectric loss was also increased. When Nd₂O₃ content was 0.003mol, the dielectric constant was increased, and the dielectric loss was decreased, which was suitable for application in condenser. The resistivity was decreased obviously with the increasing of Nd₂O₃ contents, the resistivity was the smallest when Nd₂O₃ content was 0.001mol. The Curie-temperature was also decreased with the increasing of Nd₂O₃ contents.     

聚吡咯葡萄糖氧化酶电极的生物电化学响应

采用分步骤合过程，制备了以聚吡咯膜为载体的葡萄糖氧化酶电极，探讨了其生物电化学响应特性，计算了酶催化反应的有关动力学参数。与溶解态酶相比，该电极表现出良好的生物电化学特征，而且酶蛋白对溶液温度的稳定性有显著提高。     

锰为中心原子的三元杂多配合物的合成与氧化还原性质研究

用直接法合成了以锰为中心原子的过渡元素和钨的三元杂多配合物,经ICP和TG曲线确定其化学式为K5,6[MnM(OH2)W11O39]·xH2O(M=Mn2+,Fe3+,Co2+,Ni2+,Cu2+,Zn2+和Cd2+),采用IR,UV,XRD和XPS等手段对配合物结构进行了表征,用循环伏安测定了其系列配合物的氧化还原性质,得出系列配合物的氧化性顺序,同时讨论配合物的热稳定性.     

稀土气相扩渗BaTiO3基PTC陶瓷的NTCR效应

采用稀土气相扩渗法制备了La改性的BaTiO3基PTC陶瓷,并对其室温电阻率的变化及温-阻效应进行了研究.结果表明,BaTiO3基PTC陶瓷经La气相扩渗后,室温电阻率从2.7×109Ω.m下降到220Ω.m,在25-500℃范围内,电阻率随温度升高单调递减,从220Ω.m降至5.8Ω.m,产生了明显的NTCR效应.结合XRD,SEM,EDAX以及介电性能测试结果分析了La气相扩渗BaTiO3基PTC陶瓷NTCR效应的形成机理,建立了NTCR效应的物理结构模型.     

稀土对BaTiO3陶瓷的气相化学热扩渗及其电性能研究

采用气相法对钛酸钡陶瓷扩渗稀土元素，稀土扩渗使BaTiO₃陶瓷的电性能发生了显著变化。室温电阻率明显下降，从4.3×10⁹Ω·m变为4.84Ω·m;随着频率增大和温度升高，交流电导逐渐增大，BaTiO₃陶瓷的导电性更强。稀土扩渗使BaTiO₃陶瓷的介电常数明显增加，尤其在低频下增加显著;介电常数随温度的变化呈明显的PTC效应，并使BaTiO₃陶瓷的居里温度升高为124.9℃。经XRD分析，扩渗的稀土元素并没有进入BaTiO₃陶瓷的晶格中，而是存在于晶界上。经XPS测试分析，稀土扩渗后的BaTiO₃陶瓷中钡、钛、稀土等都存在着不同程度的变价，因而导致了BaTiO₃陶瓷电阻率的降低。TG-DTA曲线分析表明，稀土扩渗后的BaTiO₃陶瓷有较好的高温热稳定性。     

La_2Ti_6O_(15)-CeTi_(21)O_(38)-PbTiO_3 ceramics formed in gaseous penetration of La-Ce into PbTiO_3 and their electric properties

PbTiO3 ceramics, which are typical ferroelectric materials, are useful in various applied fields. For example, it has a very good candidacy for piezoelectric materials for high temperature and high sensibility. In recent years, the studies on doped PbTiO3 ceramics have received consid-erable attention[1—3]. The modified PbTiO3 ceramics doped with Ca2+, Sm3+, Y3+, Ce4+ etc. have some better properties: their Curies temperature decreases, their tetragonal distortion degree de-grades and th…     

硅钨多金属氧酸盐气相扩渗制备钾钨青铜的研究

通过高温固气反应对α-Keggin结构的K4SiW12O40，K6[SiFe(OH2)W11O39]，K7[SiFe3(OH2)3W9O37]和K10[SiMg3(OH2)3W9O37]进行了氯化钕扩渗研究．经X射线能谱(EDS)和X射线光电子能谱(XPS)分析表明氯化钕可渗入到化合物的体相中．X射线粉末衍射(XRD)谱图表明，扩渗后原母体化合物的笼型结构被破坏，WO6八面体重新键合形成四方结构的钾钨青铜化合物K0.57WO3，晶胞参数a=b=1．2302nm，c=0．38355nm．