MnO对SrTiO_3压敏电阻组织性能的影响

本文研究了MnO加入量对SrTiO3压敏电阻器组织性能的影响。通过金相显微组织的观察,发现当MnO加入量达到0.1mol%时,压敏电阻晶粒尺寸比较大,且均匀致密。而对电性能的测试发现,压敏电压(E10、E1)、非线性系数α、损耗tgδ也是在MnO加入量达到0.1mol%时处于最低值,此时E10为5.09V,E1为3.42V,α为5.79,tgδ为0.38,电容量C却在此时取最大值,为105.21nf。同时还研究了压敏电阻器的焊接变化率,发现ΔE10、Δα都比较小,由此可见,焊接前后的性能比较稳定。     

TiO_2和CuO掺杂对ZnO导电陶瓷中电子密度和电阻率的影响

测量了ZnO-TiO2和ZnO-CuO导电陶瓷的正电子寿命谱及其电阻率,研究了TiO2和CuO掺杂对ZnO陶瓷中电子密度和电阻率的影响。结果表明:在ZnO中加入少量的TiO2,随着ZnO陶瓷中TiO2含量的增加,样品中的自由电子密度升高,电阻率降低;在ZnO中加入少量的CuO,随着ZnO陶瓷中CuO含量的增加,样品中的自由电子密度降低,电阻率升高。     

Y2O3掺杂对低压氧化锌压敏电阻材料结构和电学性能的影响

通过掺杂研究了微量Y2O3对低压氧化锌压敏电阻的电性能影响,并采用SEM测试手段对其微观组织结构进行了分析研究,从理论上探讨了Y2O3影响低压氧化锌压敏电阻电性能与组织的机理.研究结果表明,在0～0.07%(摩尔分数)掺杂范围内,随着Y2O3含量的增加,低压氧化锌压敏电阻的电场强度明显提高;当Y2O3含量超过0.07%时,电场强度又呈下降趋势.低压氧化锌压敏电阻掺杂Y2O3后,非线性指数α增大,漏电流IL减小,但当掺杂量在0.06%～0.09%(摩尔分数)的范围内,漏电流IL和非线性指数α的变化不大.其原因是Y2O3加入到氧化锌压敏电阻中,Y主要以固溶的形态分布于ZnO晶内和晶界处,使ZnO晶体的自由电子浓度增大,进而使填隙锌离子Zni的总浓度下降,引起填隙锌离子的传质能力下降,抑制了ZnO晶粒的生长,因而晶粒尺寸随Y2O3掺杂量的增加而减小.     

Bi2O3掺杂对ZnO压敏电阻性能的影响及其机理

采用传统电子陶瓷工艺制备了ZnO压敏电阻陶瓷,研究了Bi_2O_3的掺杂浓度对压敏陶瓷的显微结构和电学影响。利用多种表征手段对样品的性能进行分析。研究结果表明:压敏陶瓷的主晶相为铅锌矿型结构;随着Bi_2O_3浓度增大,压敏陶瓷的主要衍射峰逐渐向低角度方向偏移,同时出现明显的晶界相,且压敏陶瓷的平均晶粒尺寸呈先增大后减小趋势;当Bi_2O_3浓度为2.5mol%时,压敏陶瓷具有均匀的显微结构和较好的电学参数,此时平均晶粒尺寸D为225nm,击穿场强E_(1mA)达到最小值4600V/cm,非线性系数α达到最大值55.8,电阻在100KHz时的损耗角正切tanδ达到极小值(约0.1),相对介电常数ε_r约为232。所制备的ZnO压敏陶瓷具有较好的压敏特性和较低的损耗,有利于改善ZnO基避雷器的综合性能。     

Cr2O3对(Co,Ta)掺杂的SnO2压敏电阻电学特性的影响

研究了Cr对(Co,Ta)掺杂的SnO2压敏材料电学性质的影响.当Cr2O3的含量从0增加到0.15mol%时,(Co,Ta)掺杂SnO2压敏电阻的击穿电压从206V/mm增加到493V/mm;1kHz时的相对介电常数从1968猛降至498;晶界势垒高度分析表明,SnO2晶粒尺寸的迅速减小是样品击穿电压增高、相对介电常数急剧降低和电阻率迅速增大的主要原因.对Cr含量增加引起SnO2晶粒减小的原因进行了解释.掺杂0.15mol% Cr2O3的SnO2压敏电阻非线性系数为24,击穿电压达498V/mm,在高压保护领域有很好的应用前景.     

稀土氧化物Pr2O3掺杂对高压ZnO压敏电阻性能的影响

采用低温固相化学反应法制备了Pr2O3掺杂的ZnO纳米复合粉体,并用此粉体在不同烧结温度下制备了高压ZnO压敏电阻.采用X射线衍射、比表面测试、透射电镜、扫描电镜等手段对制备的ZnO纳米复合粉体及高压ZnO压敏电阻进行了表征,并与未掺杂ZnO压敏电阻进行了对比研究,探讨了稀土氧化物Pr2O3掺杂对高压ZnO压敏电阻电性能的影响机制.结果表明:较低的烧结温度(1030～1130℃)时,掺杂的稀土氧化物Pr2O3偏析于ZnO晶界中,有活化晶界、促使晶粒生长的作用;同时,Pr2O3掺杂导致1080℃烧结的ZnO压敏陶瓷体中晶体相互交织形成晶界织构,比未掺杂的更均匀和致密,这有助于高压ZnO压敏电阻晶界性能的改善,从而提高其综合电性能.当烧结温度为1080℃时,Pr2O3掺杂的高压ZnO压敏电阻的综合电性能最佳:电位梯度为864.39 V/mm,非线性系数为28.75,漏电流为35 μA.     

CuO掺杂SrFe0.9Sno.1O3-δ负温度系数厚膜热敏电阻的电学性能

采用印刷法制备了CuO掺杂SrFe0.9Sn0.1O3-δ(CSFS)厚膜负温度系数(NTC)热敏电阻(掺杂量为20mol%～50mo1%).对其微观结构及电性能研究发现:随着CuO掺杂含量的增加,厚膜表面变得更加致密,室温电阻逐渐降低至0.46 MΩ,而热敏常数基本保持在3300K附近.CuO的加入导致SrFe0.9...     

WO_3电变色涂层的研究

本文对真空热蒸发 WO_3涂层的电变色特性进行了研究,在室温、真空度为7.5×10~(-7)～7.5×10~(?)Pa 条件下,蒸发沉积的 WO_3涂层为无定形氧化物,经热处理后,无定形氧化物可转化为结晶型。该涂层于液态电解质中,加电场后具有可逆的变色和褪色效应。X 光衍射实验发现,变色后的涂层由原来的三斜 WO_3晶体变成了 H_(0.1)WO_3斜方晶体。本文还用扫描电子显微镜对热处理前后涂层的表面形貌进行了分析。     

CuO掺杂对10NiO-NiFe2O4复合陶瓷导电性能的影响

利用冷压-烧结技术制备了CuO 掺杂的10NiO-NiFe2O4复合陶瓷,研究了CuO 掺杂量对10NiO-NiFe2O4复合陶瓷物相组成、显微结构、致密度及导电率的影响.结果表明:当CuO掺杂量为0～12.5%(质量分数)时, 烧结样品中主要含有NiO、Cu和NiFe2O4、CuO在氮气气氛下分解为金属Cu,在烧结温度下为液相促进了致密化烧结;1473K烧结时,8.75%CuO掺杂样品的相对密度最大,达到94.43%,比未掺杂样品的相对密度提高了18.16%;当CuO掺杂量为4%时,在1233K温度下样品达到最大导电率5.169S/cm,是未掺杂样品的导电率1.026S/cm的5倍.     

Nb、Y共掺杂对PZT陶瓷微结构和电学性能的影响

研究了在Pb(Zr0.52Ti0.48)O3基体中同时掺入高价离子Y3+和Nb5+后,固溶体Pb1.03-xYx[(Zr0.52Ti0.48)1-x]O3(x=0～0.05)的晶相、微观结构及电学性能.实验结果表明共掺的Y3+和Nb5+离子抑制晶粒生长,改善材料的烧结致密度;随掺杂量x的增加,晶格常数c和晶格四方度c/a减小,晶相由四方相逐渐向菱形相转变,影响晶相和晶格参数的主要因素是Y3+离子;当掺杂量x=0.015时,材料的电性能最佳(介电常数ε33/εo=1366,压电系数d31=-139.8pN/V,e31=-9.2N/V·M,机电耦合系数kp=0.60和剩余极化值Pr=44).     

稳定WO3乳液的制备及其电变色性能的研究

在两亲高分子化合物的存在下,于水溶液中合成了稳定的WO3颗粒悬浮乳液,颗粒分布在100～230nm范围内.乳液放置数月不会发生沉降.SEM表征结果表明,由此乳液形成的薄膜的表面呈多孔颗粒状.电变色性能测试表明薄膜的变色具有良好的可逆性.在扫描速度为100mV/s时,薄膜第一次循环的还原电量QR为10.8mC·cm-2,氧化电量QO为10.3mC·cm-2,电量损失率仅为5%,着色效率(CE)为69.8cm2/C.现场计时电流实验表明,薄膜具有很快的电变色速度.     

Effects of CuO doping on the electrical properties of 0.98K0.5Na0.5NbO3-0.02BiScO3 lead-free piezoelectric ceramics

CuO-doped 0.98K_0.5Na_0.5NbO₃-0.02BiScO₃ (0.98KNN-0.02BS-xCu) lead-free piezoelectric ceramics have been fabricated by ordinary sintering technique. The effects of CuO doping on the dielectric, piezoelectric, and ferroelectric properties of the ceramics were mainly investigated. X-ray diffraction reveals that the samples at doping levels of x ≤ 0.01 possess a pure tetragonal perovskite structure. The specimen doped with 1 mol% CuO exhibits enhanced electrical properties (d₃₃ ~ 207 pC/N, k_p ~ 0.421, and k_t = 0.424) and relatively high mechanical quality factor (Q_m = 288). These results indicate that the 0.98KNN-0.02BS-0.01Cu ceramic is a promising candidate for lead-free piezoelectric ceramics for applications such as piezoelectric actuators, harmonic oscillator and so on.     

CuO掺杂对 SnO2压敏材料性能的影响

研究了掺杂 CuO对 SnO2· Ni2O3· Ta2O5压敏材料电学性能的影响.实验发现,随着 CuO的 掺杂量从 0.50mol%增加到 1.50mol%,材料的压敏电场强度从 132V/mm升高到 234V/mm,相对 介电常数从 4663减小到 2701.电场强度变化的原因是 CuO掺杂引起的晶粒尺寸变化,随掺杂量 增加晶粒尺寸从 18.8μ m减小到 13.3μ m.未固溶于 SnO2晶格而偏析在晶界上的 CuO阻碍了相 邻 SnO2晶粒的融合 ,这导致了晶粒尺寸的减小.为了解释 SnO2· Ni2O3· Ta2O5· CuO电学非线性 性质的起源,本研究对前人的晶界缺陷势垒模型进行了修正.对该压敏材料进行了等效电路分析, 实验测量与等效电路分析结果相符.     

Al doping effect on microstructure, electrical properties, dielectric characteristics, and aging behaviors of ZPCCY-based varistors

The Al doping effect on the microstructure, electrical properties, dielectric characteristics, and aging behaviors of ZPCCY-based varistors was investigated in the range of 0.0–0.1 mol%. The breakdown electric field in the E-J characteristics decreased in a wide range from 4,921 to 475 V/cm with increasing amounts of Al₂O₃. The nonlinear properties were improved by increasing amounts of Al₂O₃ up to 0.005 mol%, whereas the further additions caused it to decrease. The highest nonlinear coefficient (α = 45.2) was obtained when Al₂O₃ concentration is 0.005 mol%. The Al₂O₃ acted as a donor due to the increase of electron concentration in the small range of 0.0–0.1 mol%. On the other hand, an appropriate addition of Al₂O₃ in the range of 0.001–0.005 mol% was found to significantly improve the electrical stability against DC accelerated aging stress.     

Effects of cobalt doping on the electrical characteristics of Al-doped ZnO varistors

The effects of cobalt additive on the electrical characteristics of the Al-doped ZnO varistors are studied in this paper. The current-voltage characteristics of the varistor samples have been investigated in a range from small to large current. With the amount of the doped cobalt increased, the leakage currents of the Al-doped ZnO varistors are inhibited, and their nonlinear coefficients increase remarkably as well. In addition, their breakdown electric fields increase in a small extent and their residual voltage ratios change slightly. Furthermore, the donor densities and the barrier heights of samples decrease with the cobalt content increased. The XRD patterns show that the Bi-rich phase and the willemite phase vary obviously in the varistor samples with various content of cobalt additive.     

Effects of In2O3 doping on microstructure and electrical properties of ZnO low-voltage varistor

Journal of Materials Science: Materials in Electronics - In this work, high-performance ZnO–Bi2O3 based low-voltage varistors were prepared by doping In2O3. When the breakdown voltage was...     

光致变色纳米WO3薄膜研究进展

介绍了纳米WO3薄膜的光致变色机理,并对WO3薄膜的各种制备方法进行了分析比较.概述了WO3薄膜的各种表征手段和近年来国内外的研究现状等,并对其未来发展趋势进行展望.     

Effect of microwave sintering on the microstructure and electrical properties of low-voltage ZnO varistors

Coarse-grained ZnO varistors for low-voltage applications were prepared by microwave sintering technique under different soaking times of 5–150?min. For comparison, a low-voltage ZnO varistor was also prepared through a conventional sintering process. Microwave sintering remarkably enhanced the grain growth rate of ZnO varistors. Average grain size of the sample prepared by microwave sintering in 15?min was about 20?µm, which is similar to the grain size of sample prepared conventionally in 150?min time. In addition to grain growth, an increase in microwave sintering time led to precipitation of zinc titanate (Zn₂TiO₄) on the top surface of samples which sintered for long dwell times. X-ray diffraction and scanning electron microscopy results from different points of the samples declared that precipitation of Zn₂TiO₄ phase is due to the high rate of bismuth evaporation of Bi-rich liquid from top surface and the reaction between remaining titanium ions on the surface with ZnO. The results showed that increasing sintering time from 5 to 150?min increased the grain size from 14 to 33?µm, consequently, the breakdown field decreased from 90 to 27?V/mm, respectively. These changes led to a switch in the varistor application, from low to very low voltage.     

AST液相掺杂对低电阻率、高抗电强度BaTiO3半导瓷显微结构及电性能影响

通过改变低电阻率BaTiO3半导体陶瓷中液相添加剂AST的含量，采用XRD和SEM显微分析方法研究了AST含量对低电阻率，高抗电强度BaTiO3半导体陶瓷显微结构的影响，研究结果指出，BaTiO3半导体陶瓷中AST的引入量对晶界厚度的控制存在两个临界点，晶界厚度对低电阻率，高抗电强度BaTiO3半导体陶瓷的显微结构和电性能产生重要影响。     

Influence of processing parameters on the microstructure and electrical properties of multilayer-chip ZnO varistors

Multilayer-chip varistors based on ZnO with lead zinc borosilicate glass instead of Bi₂O₃ were prepared by tape casting and green-sheet lamination processes using a non-aqueous slurry system. The influences of slurry composition and the degassing process on the microstructure and non-ohmic properties of multilayer-chip varistors were studied. The electrical properties of chip varistors can be influenced substantially by the pore defects resulting from an unsuitable slurry formulation for the tape-casting process. The sintering temperature of the chip varistors was lowered to 1100 C and silver-palladium alloys were employed as internal electrodes. The non-linear coefficients of 27–32 and breakdown voltages of 7.6–24.5 V were achieved by controlling the green-sheet thickness and sintering temperatures in the present study. The V _br/V _br values for the chip varistors lie within ± 10%, indicating excellent surge-withstanding capability.