(LaMn_(0.8)Al_(0.2)O_3)_(1-x)(Al_2O_3)_x(0.05≤x≤0.2)NTC热敏陶瓷材料制备及电性能研究

采用氧化物固相法制备(LaMn0.8Al0.2O3)1-x(Al2O3)x(0.05≤x≤0.2)系列负温度系数(Negative Temperature Coefficient,NTC)热敏陶瓷材料。利用热重-差热(TG-DSC)、X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDS)、阻温特性以及老化性能测试等手段,确定了材料粉体最佳煅烧温度,表征了陶瓷体物相、形貌、元素含量、电学性能、稳定性与Al2O3含量的关系。结果表明:(LaMn0.8Al0.2O3)1-x(Al2O3)x(0.05≤x≤0.2)系列热敏陶瓷材料电阻率随着Al2O3含量增加显著增大,但材料常数B值增加平缓。当x=0.15时,该陶瓷材料呈现出低B(2816.44 K)、高阻(11893.89?·cm)的优良电学特性。热敏电阻经125℃老化500 h,阻值漂移(ΔR/R)均小于0.94%。     

高压电常数(Ba_(0.85)Ca_(0.15))(Ti_(0.9)Zr_(0.1-x)Sn_x)O_3陶瓷结构与性能研究

采用传统固相法制备了(Ba0.85Ca0.15)(Ti0.9Zr0.1-x Snx)O3(CBTZS-x)无铅压电陶瓷,研究了不同Sn含量(x=0~0.1)对CBTZS-x陶瓷相结构、介电以及压电性能的影响。实验结果表明:所有样品均为纯钙钛矿结构;随着Sn含量增加,室温下样品逐渐由三方和四方相共存结构转变为四方相结构,且三方-四方相转变温度T R-T和居里温度TC均逐渐减小,当x=0.04时,TR-T更接近于室温,此时表现出优异的压电性能;样品的剩余极化强度Pr和矫顽场Ec随着x增加均呈现出减小的趋势,而相对介电常数εr则逐渐增大。当x=0.04时,CBTZS-x材料的综合性能最佳:d33=665pC/N,kp=55.6%,εr=4520,Pr=12.5μC/cm2,Ec=1.6 kV/cm,表明该陶瓷材料具有很好的应用前景。     

复合添加La_2O_3/MgO对(Zr_(0.8)Sn_(0.2))TiO_4陶瓷性能的影响

讨论了复合添加La2O3/MgO对(Zr0.8Sn0.2)TiO4介质陶瓷烧结机制和微波介电性能的影响。结果表明,La2O3/MgO对(Zr0.8Sn0.2)TiO4的烧结有一定的促进作用,但La2O3/MgO添加量的增大会造成晶格缺陷和残留气孔的增多,从而导致材料的密度和Q×f降低。在1320℃保温12h、La2O3/MgO添加量为0.9wt%时,(Zr0.8Sn0.2)TiO4介电性能最好,其εr=37.14,Q×f=36600,τf=7.77×10-6/℃。     

Cobalt-free Composite Ba_(0.5)Sr_(0.5)Fe_(0.9)Ni_(0.1)O_(3-δ)-Ce_(0.8)Sm_(0.2)O_(2-δ) as Cathode for Intermediate-Temperature Solid Oxide Fuel Cell

New cobalt-free composites consisting of Ba0.5Sr0.5Fe0.9Ni0.1O3-δ(BSFN) and Ce0.8Sm0.2O2-δ(SDC) were investigated as possible cathode materials for intermediate-temperature solid oxide fuel cell (IT-SOFC). BSFN, which was synthesized by auto ignition process, was chemically compatible with SDC up to 1100℃ as indicated by X-ray diffraction analysis. The electrical conductivity of BSFN reached the maximum value of 57 S·cm-1 at 450℃. The thermal expansion coefficient (TEC) value of BSFN was 30.9×10-6K-1 , much higher than that of typical electrolytes. The electrochemical behavior of the composites was analyzed via electrochemical impedance spectroscopy with symmetrical cells BSFN-SDC/SDC/BSFN-SDC. The area specific interfacial polarization resistance (ASR) decreased with increasing SDC content of the composite. The area specific interfacial polarization resistance (ASR) at 700℃ is only 0.49, 0.34 and 0.31 Ω·cm2 when 30, 40, and 50 wt% SDC was cooperated to BSFN, respectively. These results suggest that BSFN-SDC is a possible candidate for IT-SOFC cathode.     

Pb(Hf_(0.3)Ti_(0.7))O_3铁电薄膜的制备与性能研究

采用脉冲激光沉积方法在不同温度下生长Pb(Hf0.3Ti0.7)O3(PHT)铁电薄膜,利用各种表征手段测试并分析薄膜的微观结构和电性能。研究表明,生长温度为400℃沉积的PHT薄膜具有良好的(111)择优取向;PHT薄膜矫顽场(2Ec)为390 kV/cm,剩余极化强度(2Pr)为53.1μC/cm2,经1.5×109次翻转后剩余极化强度保持85%;PHT薄膜绝缘性能良好,相对介电常数约为540。PHT薄膜有望应用于铁电随机存储器。     

Ca[(Li_(1/3)Nb_(2/3))_(0.8)Sn_(0.2)]O_(3-δ)-xTiO_2陶瓷的微波介电特性

研究了Ca[(Li1/3Nb2/3)0.8Sn0.2]O3-δ-xTiO2(0≤2≤0.2)陶瓷的微观结构及微波介电特性.当0≤x≤10%(摩尔分数,下同)时,体系为单一钙钛矿相.随Ti4+含量的增加,B位1:2有序度下降,品质因素减小,谐振频率温度系数先由-22.6×10-6/℃增加到-11.1×10-6/℃,然后向负值方向移动.当Ti4+含量为10%时,陶瓷微波介电性能最佳:εr=29.3,Qf=2684GHz,τf=-11.1×10-6/℃.     

TbDyFe掺杂对(Ba_(0.85)Ca_(0.15))(Ti_(0.9)Zr_(0.08)Sn_(0.02))O_3无铅压电陶瓷组织与电性能的影响

为获得BCZTS无铅压电陶瓷优良的电性能,通过对其掺杂TbDyFe,采用传统固相烧结法制备(Ba0.85Ca0.15)(Ti0.9Zr0.08Sn0.02)O3-x TbDyFe(BCZTS-x TbDyFe)无铅压电陶瓷,分析不同TbDyFe(x=0~0.4wt.%)含量对BCZTS无铅压电陶瓷微结构、压电性能、介电性能和铁电性能的影响,并利用XRD、SEM等方法分析表征样品。结果表明:所有样品均为单一的钙钛矿结构;掺杂TbDyFe后陶瓷的晶粒尺寸变小。由介电温谱可知,掺杂TbDyFe后BCZTS体系出现介电弛豫行为。当掺杂x=0.1wt.%时,无铅压电陶瓷材料的综合性能优异:d33=500 p C/N,kp=40%,εr~5955,tanδ~1.9%,Pr=6.6μC/cm2,Ec=2 k V/cm。