共查询到20条相似文献,搜索用时 203 毫秒
1.
用固相反应合成了Ln1-xSrxMnO3(Ln=Pr,Nd,Sm,Gd,Yb和Y,x≤0.5)系钙钛矿型多元氧化物,用X光衍射分析测定了反应产物的相组成和结构类型.离子半径>0.1A的Pr,Nd,Sm,Gd等取代后的Ln1-rSrxMnO3仍具有正交LaMnO3的结构,而离子半径<0.95A的Y和Yb取代后的产物,则为六方结构(Yb,Y)MnO3及第二相Sr(Yb,Y)2O4还测定了产物的烧结性能和电导率.发现(Pr,Nd,Sm)1-xSrxMnO3的电导率比La1-xSrxMnO3约高一个数量级以上,而且都能在ZrO2固体电解质上形成结合良好的膜材,所以有可能成为另一类性能良好的燃料电池的阴极材料. 相似文献
2.
用于燃料电池的Ln1—xSrxMnO3系阴极材料的研究 总被引:5,自引:2,他引:3
用固相反应合成了Ln1-xSrxMnO3系钙钛矿型多元氧化物,用X光衍射分析测定了反应产物 相组成和结构类型。离子半径〉0.1A的Pr,Nd,Sm,Gd等取代后的Ln1-xSrxMnO3仍具有正交LaMnO3的结构,而离子半径〈0.95A的Y和Yb取代后的产物,则为六方结构(Yb,Y)MnO3及第二相Sr(Yb,Y)2O4。还测定了产物的烧结性能的电导率。发现(Pr,Nd,Sm)1-xSrxMnO 相似文献
3.
以LiTi2(PO4)3为基以天然高岭石为起始原料,经高温固相反应(950~1150℃)制得了 一系列锂快离子导体材料Li1+2x+yAlxYbyTi2-x-ySixP3-xO12(以下简称Al-Yb-Lisicon).系统 的合成温度随x和y值的增大而降低.应用交流阻抗技术测定的电导率数据结果表明y=0.3, x=0.1的合成物的电导率最好,400℃时电导率达2.45×10-2S/cm, 200~400℃内的电导激 活能为38.3kJ/mol.XRD分析结果表明在y=0.3,x≤04及y=0.5,x≤0.3的组成范围内 均能得到空间群为R3c的合成物. 相似文献
4.
应用差热分析、X射线粉末衍射及电测量技术对Na2Mo0.1S0.9O4(α)-Pr2(SO4)3体系进行了研究,结果表明,在Na2Mo0.1S0.9O4相中加入少量的Pr2(SO4)3就可以形成完全固熔体,且无任何相变存在,当Pr2(SO4)3含量达到4mol%时,电导率较纯Na2Mo0.1S0.9O4提高两个数量级(553K时,σ=1.09×10^-3Scm^-1),同时还证明了该类导体的导电机 相似文献
5.
无Co混合导电型陶瓷透氧膜的制备和性质研究 总被引:2,自引:0,他引:2
首次合成了Sr10-n/2BinFe20Om(n=2,4,6,8,10等)系列氧化物透氧膜,它们具有较高的透氧能力,其中,样品n=10在1100K时的透氧率为0.90ml(STD)/(cm2·min),比Sr1-xBixFeO3高约两倍.Sr1-xBixFeO3(x=0.1,0.3,0.5)系列的透氧率随Bi含量增加而增大.通过两个系列氧化物的XRD和化学组成的对比,发现Bi离子含量和晶格空位浓度对透氧能力大小起决定性作用. 相似文献
6.
首次制备了一类新型的(Sb2O3)1-x(Sb2S3)x的氧硫混合体系玻璃,测定了玻璃的组成,形成区域,并用DTA,IR,UV光谱对其性能进行了研究,同时与Sb2O3单组份玻璃,Sb2O3-RX2(R=二价金属离子)系玻璃进行了比较,该玻璃易于制备,化学稳定性好,透光区0.7~7.0μm,Tc-Tg〉90℃,通过远红外光谱的分析,对玻璃的结构进行了初步研究。 相似文献
7.
应用差热分析、X射线粉末衍射及电测量技术对Na2Mo(0.1)S(0.9)O4(α)-Pr2(SO4)3体系进行了研究,结果表明,在Na2Mo(0.1)S(0.9)O4相中加入少量的Pr2(SO4)3就可以形成完全固熔体,且无任何相变存在,当Pr2(SO4)3含量达到4mol%时,电导率较纯Na2Mo(0.1)S(0.9)O4提高两个数量级(553K时,σ=1.09×10(-3)Scm(-1)),同时还证明了该类导体的导电机理,揭示了电导率与有效空位浓度、掺杂剂浓度及温度之间的依赖关系。 相似文献
8.
本文研究了轻稀土负磁致伸缩SmFe_x(1.40<x<1.94),Sm_xDy_(1-x)Fe_y(0.84<x<0.92.1.80<y<1.90),Sm_(0.90)Dy_(0.10)(Fe_(0.95)Al_(0.05))_(1.80)晶体的制备、热处理及磁学性能,发现SmFe_x合金的λ-x曲线存在两个峰值,峰值的x点随热处理发生的变化有一定的规律性,还比较了热处理前后,Sm-Fe、Sm-Dy-Fe和Sm-Dy-Fe-Al的相组成对性能的影响。热处理用于改善磁致伸缩性能,并且制得了高磁致伸缩性能的SmFe_2和(Sm,Dy)Fe_2合金。 相似文献
9.
10.
Li1+2x+yAlxNdyTi2-x-ySixP3-xO12系统的锂快离子导体研究 总被引:3,自引:0,他引:3
Li1+2x+yAlxNdyTi2-x-ySixP3-xO12锂快离子导体可以用精选的天然高岭石Al4「Si4O10」(OH)8为起始原料,经与Li2Co3、TiO2、NH4H2PO4进行高温(800-1000℃固相反应约20h而制得,一个空间群属于R3C的固溶体导电相可在y=0.5,x≤0.3和y=1.0,x≤0.4的组成范围内发现,该盯具有较好的电导性较低的活化能,起始组成y=1.0,x=0. 相似文献
11.
Ba1-xSrxTi0.88Sn0.12O3陶瓷结构与介电性能的研究 总被引:2,自引:0,他引:2
采用高温固相烧结法制备了Ba1-xSrxTi0.88Sn0.12O3(x=0.10,0.20,0.30,0.40,0.50)陶瓷,研究了Sr含量及烧结温度对Ba1-xSrxTi0.88Sn0.12O3陶瓷结构与介电性能的影响.XRD初步分析表明Ba1-xSrxTi0.88Sn0.12O3陶瓷在室温为立方钙钛矿结构.进一步的研究表明Ba1-xSrxTi0.88Sn0.12O3陶瓷的介电性能与对A位、B位进行的离子取代密切相关.随着Sr含量的增加,不同烧结温度下Ba1-xSrxTi0.88Sn0.12O3陶瓷的介电性能下降,相变温度Tc移向低温.尽管在所研究的组分范围内Ba1-xSrxTi0.88Sn0.12O3表现出扩散相变铁电体的特征,但是典型的介电弛豫行为并没有被观察到. 相似文献
12.
本文采用固相反应法制备了xSrTiO_3/(1-x)CaCu_3Ti_4O_(12)(x=0,0.2,0.4,0.6,0.8,1)复合陶瓷,研究了复合材料的物相、微观结构和宽温度宽频率范围内的介电性能。结果表明:在1348~1600K的温度范围内烧结能够得到致密性良好的xSrTiO_3/(1-x)CaCu_3Ti_4O_(12)(x=0,0.2,0.4,0.6,0.8,1)复合陶瓷。频率为100kHz时,样品的室温介电常数随SrTiO_3含量的增加而减少,从71358(x=0)单调减少至270(x=1),其变化规律遵循Lichtenecker法则。介电损耗随SrTiO_3含量的增加先增大后减少。当x=0.2时,样品与CaCu_3Ti_4O_(12)陶瓷的介电性能相似,存在低温的介电弛豫和巨介电常数平台。随着SrTiO_3含量的增加,复合陶瓷的低温介电弛豫激活能增大,介电响应被抑制,而高温介电响应由于高温电导的影响而增强,使得CaCu_3Ti_4O_(12)特有的巨介电常数平台随着SrTiO_3的增加逐渐消失,xSrTiO_3/(1-x)CaCu_3Ti_4O_(12)复合材料的温度依赖性增强。 相似文献
13.
采用固相烧结法制备Ba(Mg_(1/3)Nb_(2/3))O_3+x(x=0~8)%SnO_2(BMSN,x为质量分数)微波介质陶瓷,并研究SnO_2掺杂对Ba(Mg_(1/3)Nb_(2/3))O_3(BMN)微波介质陶瓷结构及介电性能的影响。XRD分析表明,陶瓷体系中存在两种相,主晶相Ba(Mg_(1/3)-Nb_(2/3))O_3和附加相Ba_5Nb_4O_(15)。随着x的增大,BMSN陶瓷体系的相结构逐渐由钙钛矿六方结构转变为立方结构,同时有序相逐渐由1∶2有序结构转变为1∶1有序结构。研究表明:添加适量的SnO_2可以促进液相烧结,当SnO_2掺杂质量分数为6%时,BMN陶瓷致密化烧结温度由纯相时的1 550℃以上降低至1 200℃,表观密度ρ=6.39g/cm3,相对理论密度为99.1%,此时BMSN陶瓷体系拥有优良的微波介电性能——高相对介电常数(ε_r=33.6),接近于零的谐振频率温度系数(τ_f=0.15×10~(-6)℃~(-1)),高品质因数与谐振频率的乘积(Q·f=112 300GHz(8GHz))。 相似文献
14.
采用固相法制备(1-x)BaTiO3-xZnNb2O6 (x=0.5mol%, 1mol%, 1.5mol%, 2mol%, 3mol%, 4mol%) (简称BTZN)陶瓷, 研究了BTZN陶瓷的烧结温度、结构、介电性能和铁电性能。BTZN陶瓷烧结温度随着ZnNb2O6含量增加逐渐降低。XRD结果表明当ZnNb2O6含量达到3mol%时出现第二相Ba2Ti5O12。介电测试结果表明随ZnNb2O6含量的增加, BTZN陶瓷介电常数逐渐减小, 而介电常数的频率稳定性逐渐增强。介电温谱表明所有BTZN陶瓷均符合X8R电容器标准。BTZN陶瓷的极化强度值随着ZnNb2O6含量的增加逐渐降低。当x=4mol%时, BTZN陶瓷获得240 kV/cm的击穿电场和1.22 J/cm 3的可释放能量密度。 相似文献
15.
Structure,magnetic properties and magnetostriction of Sm0.9Pr0.1(Fe1-xCox)2 compounds have been investi-gated by means of X-ray diffraction,a.c. initial susceptibility, extracting sample magnetometer,Mossbauer spec-troscopy and standard strain gauge techniques.The lattice parameter a of the MgCu2-type Laves compounds Sm0.9Pr0.1(Fe1-xCox)2 decreases nonlinearly with increasing Co concentration,deviating from the Vegardˊs law.Curie temperature Tc increases initially from 668 K for x=0 to 694 K for x=0.2 and then decreases to 200 K for x=1.0.The saturation magnetization Ms at temperatures 1.5K, 77K and 300K have the same variation tendency as the composition dependence of Curie temperature,in consistence with rigid-band model.The easy magnetization direction(EMD) od Sm0.9Pr0.1(Fe1-xCox)2 lies along [111] direction in the range x≤0.6,and changes to [110] for x=0.8 ,while Sm0.9Pr0.1(Fe1-xCox)2 stays in the paramagnetic state at room temperature.The composition dependence of the average hyperfine field,Hhf,demonstrates a similar variation tendency as that of the saturation magnetiza-tion Ms and Curie temperature Tc .The spontaneous magnetostricton λ111 increases with increasing Co content.The saturation magnetostriction λs decreases monotonically with increasing x,which is caused by the increase of magnetostriction constant λ100 with opposite sign to that of λ111.A two-sublattice model has been proposed to understand the intermediate region between the [111]and [110] spin configurations ,which can also be used to explain the temperature dependence of magnetization. 相似文献
16.
Shunhua WU Guoqing WANG Shuang WANG Dandan LIUInstitute of Electronics Information Engineering Tianjin University Tianjin China 《材料科学技术学报》2005,21(5):773-775
1.IntroductionRecent progress of microwave telecommunication de-mands the development and application of a variety ofmicrowave dielectric materials.The materials with highdielectric constant(ε),high quality factor(Q)and smalltemperature coefficient of resonant frequency(TCF)haveattracted the greatest interest of researchers.The com-pounds Ba(B'1/3B"2/3)O3(B'=Mg,Zn,Ni,etc.B"=Ta,Nb,etc.)with complex perovskite structure exhibit veryhigh Q value at microwave frequencies greaterthan10GHz.… 相似文献
17.
Pellets of ceramic Na1−xKxNbO3 (x = 0, 0.2 and 0.5), were prepared by conventional solid-state reaction method. Prepared samples were characterized using
XRD and SEM. The frequency and temperature variation of dielectric constant, loss tangent and dielectric conductivity of prepared
samples were measured in the frequency range from 10 KHz-1 MHz, and in the temperature range from 50–250°C for x = 0.2 and
0.5, and between 50 and 480°C for x = 0 compositions. It was observed that the dielectric constant and loss tangent decrease,
and conductivity increases with increasing frequency. Near the transition temperature the material shows anomalous behaviour
for the observed properties, and the peaks of dielectric constant and loss tangent were observed shifting towards lower temperature
with increasing frequency. 相似文献
18.
Biplab Kumar Paul Kumaresh Halder Debasis Roy Biswajoy Bagchi Alakananda Bhattacharya Sukhen Das 《Journal of Materials Science: Materials in Electronics》2014,25(12):5218-5225
Highly crystallized mullite is synthesized via sol–gel technique in presence of iron of different concentrations at different temperature. FTIR spectroscopy, XRD and FESEM characterization showed prominent mullite phase which is found to depend on the concentrations of Fe2+ ions. The phase evolution and electrical properties like dielectric constant, tangent loss, a.c. conductivity and resistivity of the composites with increasing concentration of the doped metal at different temperature have been studied. The results showed a decrease in mullite phase up to 1.2 (M) which is mainly responsible for the increasing dielectric behavior with respect to undoped mullite. The hematite phase continued to increase with increasing doping concentration. The dielectric constant decreased with frequency for all the samples attaining constancy at higher frequency, which is normal behavior for dielectric ceramics. A.c. conductivity increased with frequency following Jonscher’s power law and was found to depend on the amount of glassy phase and concentration of mobile ions present in the composites. The composite showed a minimum dielectric constant of 33.69 at 1.2 (M) concentration of iron at 2 MHz. Thus due to their good dielectric response the composite may widely be used use as electronic substrates like packaging materials for integrated high speed circuits, multilayer capacitors, high voltage insulators etc. 相似文献
19.
1. IntroductionMuch attention has been focused onmagnetostrictive materials RFe2, particularly,Tbo.zv~o.sDyo.vs~o.vFez (Terfenol-D), due to theirexcellellt magnetoelastic properties for the transducer deviceslll. Clark et al. firstly suggestedthat the pseudobinary compounds combined byTb, Dy and Fe could be constructed in an effortto reduce the anisotropy while maintaining largemagnetostrictionlZ]. Clark et al. also found in thecompensated system Tbl--.Pr.FeZ that (Tb, Pr)Fe3phase appea… 相似文献
20.
C. Z. TAN 《Journal of Materials Science》1998,33(23):5689-5693
Glasses with the compositions Pb2(1–x)Ti2xGe5O12+2x (x = 0.5, 0.4, 0.3, 0.2, 0) were prepared in order to study their electrical and optical properties. The density decreases with increasing Ti content in the glasses, and the refractive index exhibits a maximum at x = 0.4. The Raman spectra show that Ge is tetrahedrally coordinated in glasses. At a given temperature, the electrical conductivity increases with increasing Ti content while the dielectric constant shows a mixing effect that exhibits a maximum at x = 0.2. The temperature dependence of dielectric constant was discussed by means of the Langevin theory. 相似文献