共查询到19条相似文献,搜索用时 203 毫秒
1.
以传统的固相反应法制备了Bi0.5Ba0.5FeO3陶瓷,并采用X射线衍射仪、扫描电子显微镜、直流阻温测试仪和交流阻抗分析仪测试了Bi0.5Ba0.5FeO3陶瓷的微结构和电性能.分析结果表明:Bi0.5Ba0.5FeO3陶瓷具有立方钙钛矿结构,颗粒尺寸约1.0 μm;在16—280 ℃范围内,Bi0.5Ba0.5FeO3陶瓷表现出明显的负温度系数热敏效应,其热敏常数、活化能分别为6490 K及0.558 eV;介电温谱揭示,在280 ℃下Bi0.5Ba0.5FeO3陶瓷材料没有出现相变行为.对于交流阻抗谱,采用3个串联的RQ(R与Q为并联)等效部件来拟合分析,拟合结果表明拟合数据与实验数据高度匹配,且这3个等效部件分别代表晶界、晶粒和晶壳的贡献.3个部件中,晶粒对陶瓷电阻阻值的影响最大,晶壳贡献次之,晶界最小,且3个部件电阻值都显示出负温度系数效应.在25—115 ℃范围内,电学模量虚部峰频与阻抗虚部峰频始终不匹配,意味着Bi0.5Ba0.5FeO3陶瓷体内部一直表现出局域导电机理.
关键词:
0.5Ba0.5FeO3陶瓷')" href="#">Bi0.5Ba0.5FeO3陶瓷
电性能
阻抗分析 相似文献
2.
在CO2激光功率为50—300W、扫描速度为20mm/s、激光散光斑为20mm照射条件下 ,诱导非 晶Fe735Cu1Nb3Si135B9带中发生结构重组,产生定量纳米α-F e(Si)晶相形成双相组织结构材料. 利用穆斯堡尔谱研究了非晶Fe735C u1Nb3Si135B9合金激光纳米化的 超精细结构. 实验结果表明,激光诱导非晶 Fe735Cu1Nb3Si135B 9纳米化后,其超精细磁场的分布随 着激光功率变 化由单峰向双峰变化,在高功率辐照时, 出现了双峰分布,并且峰位向高场移动. 高激光 功率辐照非晶Fe735Cu1Nb3Si135 sub>B9合金纳米晶化相有四种超精细结 构,即2个超精细磁场较小的初晶相和2个超精细磁场较大的纳米晶化相. 其中超精细磁场较 大(17—25MA/m)的α-Fe(Si)相为DO3结构.
关键词:
激光
纳米晶α-Fe(Si)
735Cu1Nb< sub>3Si135B9')" href="#">非晶Fe735Cu1Nb< sub>3Si135B9
超精细结构
超精细磁场 相似文献
3.
利用脉冲激光沉积技术在LaAlO3(00l)单晶衬底上制备了La067Ba033MnO3薄膜,研究了CO2激光辐照对La067Ba033MnO3薄膜的微结构和磁电性能的影响.结果表明,经激光辐照后,La067Ba033MnO3薄膜的结晶性增强,薄膜应变减小;薄膜表面形貌由“岛状”结构变为“平原"结构,且粗糙度大大降低;同时,薄膜的饱和磁化强度、铁磁居里温度、金属—绝缘态转变温度和磁电阻增大,而矫顽场和电阻率减小.根据对传统退火效应的分析和理论计算,认为激光辐照导致的表面微结构的变化以及薄膜的氧含量和均匀性的提高对La067Ba033MnO3薄膜的磁电性能的改善与优化密切相关.
关键词:
庞磁电阻
激光辐照
脉冲激光溅射沉积 相似文献
4.
采用脉冲激光沉积技术制备了SrTiO3和SrNb0.2Ti0.8O3薄膜.X射线衍射分析表明在LaAlO3(100)单晶平衬底上生长的SrTiO3及SrNb0.2Ti0.8O3薄膜是沿[001]取向的近外延生长.随着氧压在一定范围内逐渐增大,SrTiO3薄膜的晶格参数减小,而SrNb0.2Ti0.8O3薄膜的晶格参数先减小后增大.同时摸索出制备具有二维电子气超晶格(SrTiO3/SrNb0.2Ti0.8O3)L的最佳氧压为1.0×10-2Pa.另外在LaAlO3(100)倾斜衬底上制备的SrNb0.2Ti0.8O3薄膜中观察到激光感生热电电压效应.
关键词:
0.2Ti0.8O3薄膜')" href="#">SrNb0.2Ti0.8O3薄膜
晶格参数
激光感生热电电压
脉冲激光沉积 相似文献
5.
采用了传统的固相烧结工艺,制备了不同Zr和Hf掺杂量的SrBi4Ti4-xZrxO15(x=000,003, 006,010,020)和SrBi4Ti4-xHfxO15(x=000,0005, 0015,0030,0060)的陶瓷
关键词:
4Ti4-xZrxO15')" href="#">SrBi4Ti4-xZrxO15
4Ti4-xHfxO15')" href="#">SrBi4Ti4-xHfxO15
铁电性能
介电性能 相似文献
6.
用溶胶-凝胶工艺成功制备出Bi05Na05TiO3纳米微粉,并利用此微粉烧结出高致密度的Bi05Na05TiO3陶瓷.这种新工艺制备的Bi05Na05TiO3陶瓷,其压电性能远远高于普通方法制备的陶瓷,其中压电常数d33和机电耦合系数kt分别高达102×10-12C/N和58%.同时发现,对于这种Bi05Na05TiO3陶瓷,室温时只需施加100kV/cm左右的交变电场,就可得到矩形度极好的饱和回线,得到的剩余极化Pr和矫顽场Ec分别为32μC/cm2和61kV/cm.而在100℃以上只需施加35kV/cm的极化电场就可使样品充分极化. 相似文献
7.
利用Sol-Gel法在Pt/Ti/SiO2/Si衬底上制备出Bi4Ti3O12和Bi3.25La0.75Ti3O12薄膜,研究了La掺杂对Bi4Ti3O12薄膜的晶体结构、铁电性能和疲劳特性的影响,发现La掺杂没有改变Bi4Ti3O12薄膜的基本晶体结构,并且提高了Bi4Ti3O12铁电薄膜的剩余极化值和抗疲劳性能,对La掺杂改善Bi4Ti3O12铁电薄膜性能的机理进行了讨论.
关键词:
铁电性能
4Ti3O12薄膜')" href="#">Bi4Ti3O12薄膜
3.25La0.75Ti3O12薄膜')" href="#">Bi3.25La0.75Ti3O12薄膜
sol-gel法
La掺杂 相似文献
8.
采用溶胶-凝胶法,在氧气氛中和层层晶化的工艺条件下,成功地制备了沉积在Pt/Ti/SiO2/Si(100)衬底上的铁电性能优良的Sr2Bi4Ti5O18 (SBTi)薄膜,并研究了SBTi薄膜的微结构、表面形貌、铁电性能和疲劳特性.研究表明:薄膜具有单一的层状钙钛矿结构,且为随机取向;薄膜表面光滑,无裂纹,厚度约为725nm;铁电性能测试显示较饱和、方形的电滞回线,当外电场强度为275kV/cm时
关键词:
溶胶-凝胶法
铁电薄膜
2Bi4Ti5O18')" href="#">Sr2Bi4Ti5O18 相似文献
9.
利用传统的固相反应工艺,在不同的烧结温度下制备了一系列的CaCu3Ti4O12陶瓷样品,考察了其微观结构以及介电和复阻抗方面的电学性质.研究发现这些样品在微观结构方面可分为三种类型,高介电性与微观结构有着密切的关联性.室温下,样品的低频介电常数随陶瓷晶粒尺寸的增大而提高.随着测试温度的升高,不同微观结构类型的样品呈现出不同的电学性质的变化,但其中也存在着一些相同的特征.高温下,介电频谱呈现出一个低频介电响应和两个类Debye型弛豫色散,复阻抗谱呈现出三个Cole-Cole半圆弧.将实验上观测到的电学性质的起因归于陶瓷多晶微结构中的晶畴、晶界和晶粒内的缺陷.
关键词:
3Ti4O12')" href="#">CaCu3Ti4O12
微观结构
电学性质 相似文献
10.
11.
boldmath Characterization of the BaBiO3-doped BaTiO3 positive temperature coefficient of a resistivity ceramic using impedance spectroscopy with Tc=155℃
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
BaBiO3-doped BaTiO3 (BB-BT) ceramic, as a candidate for lead-free positive temperature coefficient of resistivity (PTCR) materials with a higher Curie temperature, has been synthesized in air by a conventional sintering technique. The temperature dependence of resistivity shows that the phase transition of the PTC thermistor ceramic occurs at the Curie temperature, Tc=155 ℃, which is higher than that of BaTiO3 ( ≤ 130 ℃). Analysis of ac impedance data using complex impedance spectroscopy gives the alternate current (AC) resistance of the PTCR ceramic. By additional use of the complex electric modulus formalism to analyse the same data, the inhomogeneous nature of the ceramic may be unveiled. The impedance spectra reveal that the grain resistance of the BB-BT sample is slightly influenced by the increase of temperature, indicating that the increase in overall resistivity is entirely due to a grain-boundary effect. Based on the dependence of the extent to which the peaks of the imaginary part of electric modulus and impedance are matched on frequency, the conduction mechanism is also discussed for a BB-BT ceramic system. 相似文献
12.
The [TMA]2Zn0.5Cu0.5Cl4 hybrid material was prepared and its dielectric spectra were measured in the 10−1 Hz-106 Hz frequency range and 200-305 K temperature interval. The dielectric permittivity showed a ferroelectric-paraelectric phase transition at 293 K. Double relaxation peaks are observed in the imaginary part of the electrical modulus, suggesting the presence of grain and grain boundary in the sample. The frequency dependent conductivity was interpreted in term of Jonscher's law: σ(ω)=σdc+Aωn. The temperature dependent of the dc conductivity (σdc) was well described by the Arrhenius equation: σdcT=σo×exp(−Ea/kT). 相似文献
13.
研究了氧空位对La0.5Ca0.5MnO3 (LCMO)多晶块材的电输运和磁性质的影响. 随着氧空位的增加, 样品在高温段的电阻率一直增加, 并满足绝热小极化子模型, 而低温段的电阻率先下降后上升, 并出现明显的dR/dT>0的行为, 直至最后变为绝缘的. 氧空位的增加抑止了反铁磁相的出现, 使得脱氧的LCMO样品不发生反铁磁转变, 进一步增加氧空位则会抑制铁磁相.
关键词:
0.5Ca0.5MnO3')" href="#">La0.5Ca0.5MnO3
反铁磁相变
铁磁相变
脱氧 相似文献
14.
采用固相反应法制备了Y2O3施主掺杂的92 mol%BaTiO3-8 mol%(Bi1/2Na1/2)TiO3(BBNT8)高温无铅正温度系数电阻(positive temperature coe?cient resistivity,PTCR)陶瓷.利用透射电镜观察材料的显微结构,发现陶瓷的显微结构主要包括晶粒和晶界两部分,观察不到明显的壳层结构.进一步利用交流阻抗谱研究了陶瓷的宏观电学性能,发现陶瓷的总电阻是晶粒和晶界两部分的贡献,而晶粒电阻很小,在居里温度以上变化不大,材料的PTCR效应主要是晶界部分的贡献.当温度高于居里温度时,随着温度的升高,晶界介电常数逐渐减小,导致势垒增加,晶界电阻增大,从而产生正温度系数效应.最后,通过测试材料的介电频谱特性,研究计算了陶瓷的室温电阻率. 相似文献
15.
M. Staruch F. Ronning Q.X. Jia H. Wang 《Journal of magnetism and magnetic materials》2010,322(18):2708-6451
Epitaxial Pr0.5Ca0.5MnO3 films have been synthesized on (0 0 1) SrTiO3 substrate using a chemical solution deposition technique and two-step post-annealing process. The zero field resistivity of the films shows semiconducting behavior and a characteristic of charge ordering is observed at 230 K. The resistivity of the 10 nm film did not show any effect with the magnetic field. However, melting of charge ordering was observed for the 120 nm film at an applied magnetic field of 4 T. Large decrease in the resistivity of the 120 nm film (<100 K) resulted in magnetoresistance of nearly −100% at 75 K. 相似文献
16.
NbTi0.5Ni0.5O4 (NTNO) has been prepared using solid state synthesis and investigated as a potential anode material. The oxide form of NTNO has single phase rutile-type structure with tetragonal (P42/mnm) space group. The reduced form is a composite of nano-scaled particles of metallic Ni and Nb1.33Ti0.67O4 phase. Reduced NTNO showed high electronic conductivity up to 280 S.cm− 1 at 900 °C in reducing atmosphere, but suffers from low CTE equal to 3.78 10− 6 K− 1. Studies of NTNO as anode material were carried out in a three electrode - electrochemical half cell configuration under pure humidified H2 at 900 °C using a 2 mm thick zirconia electrolyte and without any additional current collector material. The results show a reasonable series resistance (Rs) equal to 2.7 Ωcm2 (about 50% higher than for metallic gold layers) indicating a good current collection performance for a 10 μm layer of material. The polarization resistance (Rp) was equal to 33 Ωcm2 and is attributed to a poor density of three phase boundaries (TPB) and shortage of oxide ion conduction in the anode layer. The results show the potential of NTNO as an anode material, especially after optimization of the microstructure towards the increase of TPB length. 相似文献
17.
本文研究了在真空、空气和氧气中烧结制备的三种 CaCu3Ti4O12陶瓷材料的介电特性. 交流阻抗测量结果表明在10—300 K温度范围, 三种样品的介电温谱中均出现三个平台, 其电阻实部和电容虚部在相应温度出现损耗峰, 真空条件烧结的样品具有较高的介电平台和较明显的电阻实部与电容虚部峰值, 表明氧含量和氧空位对CaCu3Ti4O12的介电性质具有重要影响, 介电温谱出现的三个平台分别源于晶粒、晶界及氧空位陷阱.温谱分析表明晶粒的激活能与烧结气氛有较大关系,氧空位引起的电子短程跳跃及跳跃产生的极化子是晶粒电导和电容的主要起源.氧空位陷阱的激活能基本与烧结气氛无关,约为0.46 eV. 氧空位对载流子的陷阱作用是CaCu3Ti4O12 低频高介电常数的重要起源. 相似文献
18.
利用固相反应法制备Pr0.5Ca0.5MnO3(PCMO)靶材,并采用脉冲激光沉积法(PLD)在n型Si(111)基片上沉积PCMO外延薄膜,研究了薄膜的输运特性及薄膜与Si衬底形成异质结的整流特性.结果表明:在80—300 K温度范围内,PCMO薄膜的阻温关系符合变程跳跃模型,随着温度的升高表现出从一维到二维再到三维的转变,分析认为可能源于轨道自由度对电子输运特性的影响.PCMO/Si异质结在磁场作用下整流特性得到改善,且在正向电流方向出
关键词:
0.5Ca0.5MnO3')" href="#">Pr0.5Ca0.5MnO3
Si
整流
正磁电阻 相似文献
19.
Yanmin Huang Danping Shi Laijun Liu Guizhong Li Shaoying Zheng Liang Fang 《Applied Physics A: Materials Science & Processing》2014,114(3):891-896
Bi0.5Na0.5TiO3 (BNT)-doped BaFe0.5Nb0.5O3 (BFN) ceramics were synthesized by a two-step solid-state reaction. Temperature dependence of dielectric properties measured at different frequencies was investigated over broad temperature and frequency ranges. Impedance spectroscopy and universal dielectric response were employed to study the relaxation behavior and conductivity mechanism of the ceramics in a frequency range from 40 Hz to 100 MHz and a temperature range from 300 K to 800 K. The complex plane impedance data revealed the bulk and grain boundary contributions toward conductivity processes in the form of semicircular arcs. The high-temperature conductivity of ceramics is attributable to thermally activated second ionized oxygen vacancy. 相似文献