Hydrothermal synthesis and dielectric properties of lanthanum titanate ceramics

Lanthanum titanate (La2/3 TiO3) powders were synthesized by hydrothermal method based on the reaction of TiO2, La(NOa)a and KOH at 160℃ for 24 h followed by the treatment of acidification. The microstructure,morphology and dielectric properties were investigated by using X-ray diffraction, scanning electron microscope,transmission electron microscope and impedance method. The results show that the La2/a TiOa particles consist of nearly homogenous and lamellar grains. The particles can be sintered into porous ceramics above 1 150℃. The dielectric properties of La2/3 TiO3 show that both the dielectric constant and the dielectric loss tangent decrease with the increase of frequency.     

LAPW能带计算方法

系统介绍了LAPW能带计算方法并给出了计算实例，最后对该方法作了总结。     

Solvothermal preparation and thermoelectric properties of quasi-binary Sn(Pb)Te-Bi_2Te_3 compounds

The alloys based on Bi2Te3 are widely known as the best thermoelectric materials currently available for thermoelectric application near room temperature. Unfortunately the efficiency for TE device is limited by poor properties of TE materials. Excellent TE materials require a perfect combination of electrical and thermal properties. The challenge lies in achieving simultaneously high power factor (2) and low thermal conductivity, which define the dimensionless figure of merit ZT=(a2s/k)T[…     

PEO-LiClO4-SiO2复合型聚合物电解质

用KH560硅烷偶联剂对纳米级SiO2粒子的表面进行了改性.并用改性后的SiO2添加到PEO和LiClO4中制备了复合型聚合物电解质.研究了该复合型聚合物电解质的热、电以及机械性能.与未改性的SiO2相比,硅烷改性的SiO2能有效提高(PEO)16LiClO4的离子电导率,同时机械性能也有明显的提高.     

PMNNT/CoFe2O4复合材料的结构和磁电性能

采用固相法制备了Pb[(Mg1/3Nb2/3)0.536(Ni1/3Nb2/3)0.128Ti0.336]O3(PMNNT)和CoFe2O4不同组分的颗粒复合材料.复合材料在1 200℃烧结后,仍保持PMNNT和CoFe2O4结构,没有新相生成,但由于不同相之间存在元素扩散,材料的性能有了改变.该材料具有铁电和铁磁特征,表现出较高的介电常数,高压电系数,较高的饱和磁化强度,低矫顽力和高磁致伸缩效应等特征,并表现出磁电效应.     

红外PCM码接收技术的研究

分析了彩电遥控器的编码及接收系统,在此基础上提出了与单片机（MCS51）的接口问题,并给出了应用实例。     

碳化硅(SiC)基材料的高温氧化和腐蚀

评述了近年来SiC材料氧化和腐蚀研究的进展,分析讨论SiC腐蚀氧化机理\影响因素\气氛和融盐等的影响,比较了SiC材料在不同条件下的氧化腐蚀情况,同时指出了存在的问题.     

掺Al_2O_3的ZnO压敏电阻的电性能和缺陷模型

研究了Al_2O_3掺杂对ZnO压敏电阻电性能的影响。对掺Al_2O_3的ZnO压敏电阻的缺陷模型进行了分析,结合缺陷分析和压敏电阻非线性导电模型讨论了Al_2O_3施主型添加剂的作用。     

COUPLED LINEAR-RESPONSE OF INHOMOGENEOUS MEDIA:A GENERAL THEORY AND ITS APPLICATIONS

A generally exact theory for predicting the effec-tive behavior of coupled linear-response for inhomogeneous me-dia is developed.The general solutions for the coupled problemsof two fields and three fields are given.The applications of thetheory in the magnetic-electric(magnetoelectricity)propertiesand the thermal-electric-mechanical properties(thermoelasti-city,piezoelectricity,and pyroelectricity)are discussed.Thefirstorder approximations of the thermal-electric-mechanicalproperties of binary transversely isotropic composites are de-rived.     

MICROSTRUCTURE-PROPERTY RELATIONSHIPS OF HETEROGENEOUS ELECTROCERAMICS

Based on an improved effective-medium theory and aproper treatment of ac response of grain boundary barrier layer,thetheoretical relationships describing ac electrical properties of heteroge-neous electroceramics are discussed in terms of the theoretical relation-ships,and some important results consistent with experimental resultsare obtained.