纳米Bi_2O_3掺杂对ZnO压敏电阻片电学性能的影响

为获得电学性能优异、生产成本低的ZnO压敏电阻片,本文采用传统陶瓷烧结技术制备ZnO压敏电阻片,研究不同含量纳米Bi_2O_3掺杂对ZnO压敏电阻片的电位梯度、漏电流、非线性系数等电性能的影响。采用压敏电阻直流参数仪对ZnO压敏电阻片的电学性能进行表征。实验结果表明,随着纳米Bi_2O_3含量的增加,ZnO压敏电阻片的电位梯度先升高后降低,漏电流变化不显著,非线性系数先增大后减小。当掺杂纳米Bi_2O_3摩尔分数为0.80%时,ZnO压敏电阻片的电学性能最佳。     

TiO2掺杂对ZnO压敏电阻低压化过程的影响

近年来，加入晶粒助长剂TiO2以实现低压化的低压ZnO压敏电阻发展迅速。实验所用配方为掺杂TiO2的98.3％ZnO-0.7％Bi2O3-1.0％TiO2(摩尔分数)和相应无TiO2掺杂的配方，在900～1200℃下烧结制备样品。给出了相分析、半定量分析及电性能测试结果。发现TiO2可以有效促进ZnO晶粒长大，降低压敏电压梯度。1100℃下，TiO2掺杂试样的平均晶粒尺寸为56.4μm，远大于无TiO2掺杂的31.8μm。大部分TiO2首先与Bi2O3反应生成Bi4(TiO4)3液相，这大大促进了ZnO晶粒生长。高于1000℃时Bi4(TiO4)3分解，分解出的TiO2与ZnO发生反应，生成Zn2TiO4尖晶石相，晶粒生长受阻，直至停止。     

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。     

V2O5掺杂ZnO-Bi2O3-CO2O3-MnCO3-TiO2低压压敏陶瓷的微结构和电性能

采用固相反应法制备V2O5掺杂的ZnO–Bi2O3–Co2O3–MnCO3–TiO2（ZBCMT）低压压敏陶瓷。利用X射线衍射、扫描电子显微镜、压敏电阻直流参数仪和阻抗分析仪研究了V2O5掺杂对ZBCMT陶瓷微结构、压敏性能、电场强度–电流密度特性和介电性能的影响。结果表明：掺摩尔分数为0.010%的V2O5时,ZBC...     

CeO2掺杂Pr6O11系氧化锌压敏电阻的研究

探讨了添加不同CeO2含量对Pr6O11系ZnO压敏电阻显微结构及电性能的影响,以期能满足特高压用高电位样度的应用需求.结果表明:随着CeO2掺杂量的增加,ZnO-Pr6O11系压敏电阻电位梯度和非线性系数有明显的提高,在掺杂量为1.0mol%时达到峰值,分别为548V/mm和42.XRD、SEM检测分析表明,CeO2并不与ZnO及其他氧化物生成新相,而是以CeO2的形式独立存在,抑制了ZnO的生成,致使填隙锌离子的传质能力下降,从而减小ZnO晶粒尺寸,并改善了压敏电阻的晶界结构和成分.     

自蔓延燃烧法合成ZnO粉体及其压敏电阻的制备

以硝酸锌、尿素以及其它添加剂为原料,通过自蔓延燃烧法一次性合成了ZnO压敏电阻用掺杂纳米粉体.用X射线衍射、扫描电镜、比表面测试、激光粒度分析等手段对所制备粉体的性能进行了表征.研究了反应物质量比对粉体性能的影响,以及煅烧温度对ZnO压敏电阻电性能的影响,并对自蔓延燃烧合成反应进行了初步探讨.结果表明:在点火温度为600℃,尿素/金属离子盐质量比为1∶1时,所制备的掺杂纳米ZnO粉体的综合性能最好.用此粉体制备的ZnO压敏电阻的电性能最佳,电位梯度为745.27V/mm,非线性系数为56.53,漏电流为6μA.     

气相火焰燃烧合成锌掺杂TiO2纳米晶的光催化性能

以四氯化钛和乙酰丙酮锌为原料,采用气相火焰燃烧合成锌掺杂TiO2纳米晶,利用XRD, XPS和ICP-AES研究了纳米晶结构,考察了锌掺杂TiO2纳米晶在紫外光辐照下催化降解罗丹明B(Rhodamine B)的活性,探讨了光催化机理. 研究结果表明,掺杂相锌主要分布在TiO2表相,并形成均匀分散的ZnO团簇;燃烧过程中锌掺杂对纳米TiO2的晶相组成及晶粒尺寸影响不大. 当掺杂量为0.21%(mol)时,样品具有最高的光催化活性. 光催化机理分析表明,TiO2与ZnO不同的能带位置使光生载流子能够有效分离,改善了纳米TiO2光催化活性.     

Fe_2O_3掺杂对ZnO-Pr_6O_(11)系压敏电阻材料电学性能的影响

通过烧结法制备了Fe2O3掺杂的ZnO–Pr6O11压敏电阻材料,研究了Fe2O3掺杂量对ZnO–Pr6O11系压敏电阻材料电学性能的影响。实验表明:当Fe2O3掺杂量小于0.005%(摩尔分数,下同)时,ZnO–Pr6O11系压敏电阻材料的非线性系数和压敏电压随Fe2O3掺杂量增大而逐渐提高。当Fe2O3掺杂量为0.005%时,压敏电压达到最大值571V/mm,非线性系数达到最大值26。当Fe2O3掺杂量大于0.005%时,非线性系数和压敏电压均急剧下降。过量Fe2O3使ZnO压敏电阻材料非线性下降的主要原因是:Fe元素偏析在晶界处,提供额外载流子降低了晶界电阻率,同时晶界处PrFeO3相的堆积会破坏晶界结构,从而影响压敏电阻材料的电学性能。     

室温固相合成掺杂ZnO纳米粉体制备ZnO压敏电阻

以金属离子盐和草酸为原料,采用室温固相化学反应合成掺杂ZnO前驱物,根据DSC-TG分析结果,将其在450℃热分解2 h,得到掺杂ZnO粉体,并用此粉体制备了片式ZnO压敏电阻。借助XRD、TEM、BET等检测手段对粉体产物的物相、形貌、粒度等进行了表征。研究了烧结温度对ZnO压敏电阻电性能的影响。结果表明,所制备的粉体为平均粒径24 nm左右、颗粒呈球状、分散性好的纤锌矿结构掺杂ZnO。在1 080℃烧结时,ZnO压敏电阻的综合电性能达到最佳,电位梯度为791.64 V/mm,非线性系数为24.36,漏电流为43μA。     

ZnO压敏电阻器的性能及发展

简要回顾了ZnO压敏电阻器的历史，阐述了ZnO压敏电阻器的性能以及当前基础性研究的现状，并对其发展进行了展望。研究了Bi2O3和TiO2的掺杂对低压ZnO压敏电阻性能和微观结构的影响规律，从理论上分析了Bi2O3和TiO2添加剂的作用机理。为ZnO压敏电阻的低压化提供了理论依据和方法。     

Effect of NiO doping on grain growth and electrical properties of ZnO-based varistors

The effects of NiO content on the grain growth and the electrical properties of the ZnO varistors were studied. The effect on the grain growth was characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometer, while the effects on the electrical properties were investigated by varistor tester, pulse surge tester and precision impedance analyzer. The results showed that the growth of the (0002) plane of the ZnO varistors was inhibited by doping NiO, which improved the electrical properties of the varistors, especially the surge shock stability. The sample doped with 1.56 mol% NiO exhibited excellent electrical properties with breakdown voltage gradient of 184.0 V/mm, nonlinear coefficient of 72.7, leakage current of 0.37 µA, clamp voltage ratio of 2.20 under 8/20 μs waveform impact of 20 kA and change rates of positive and negative breakdown voltages of < 4% under 20 times impacts of 20 kA.     

High improvement of degradation behavior of ZnO varistors under high current surges by appropriate Sb2O3 doping

The effects of Sb₂O₃ content on the microstructures and electrical properties of the ZnO varistors, especially on the degradation behavior under pulse current stress were studied. The results showed that the degradation behavior was effectively improved by doping appropriate amount of Sb₂O₃, which attributed to the homogenized microstructure and the compression of the interstitial void. The change rates of positive and negative breakdown voltage gradients of samples doped with 0.92 mol% Sb₂O₃ under 20 * 20 kA + 2 * 30 kA surges were -1.76 % and 1.56 % respectively, which was one of the best levels reported in the previous literatures. In addition, the sample exhibited excellent comprehensive electrical properties, with breakdown voltage gradient of 207.74 V mm^?1, nonlinear coefficient of 119.1, leakage current density of 1.03 × 10^-2 μA cm^-2, and clamping voltage ratio of 2.17 under 20 kA surge, making it a promising candidate for surge protector devices.     

Processing and characterizations of flash sintered ZnO-Bi2O3-MnO2 varistor ceramics under different electric fields

The dense ZnO-Bi₂O₃-MnO₂ (ZBM) varistors were prepared by flash sintering under electric fields ranging from 200 V/cm to 400 V/cm at constant heating rate (CHR) and constant furnace temperature (CFT), respectively. The structure and electrical properties of the ZBM varistors were studied via the XRD, SEM and a DC parameter instrument. The onset temperature and incubation time of flash sintering decrease with increasing electric field. The effects of the maximum limiting current on the density of the samples were also investigated. The results showed that the density of samples increase with the increasing current values. The improved electrical characteristics were obtained during constant furnace temperature flash sintering. The ZBM varistor ceramics exhibited superior comprehensive electrical characteristics under a field of 250 V/cm, in which the nonlinear coefficient is 26.4, the threshold voltage and the leakage current is 466 V/mm and 12.32 μA, respectively.     

高能球磨对Pr_6O_(11)和Y_2O_3掺杂ZnO压敏电阻微观结构和电学性能的影响

利用高能球磨法制备Pr6O11、Y2O3掺杂ZnO压敏电阻,并对球磨时间对微观结构、物相组成及电学性能的影响进行了研究和分析。高能球磨有利于微观组织的均匀化和晶粒的细化,从而提高了电学性能。当球磨时间从0到10 h时,烧结后的ZnO晶粒尺寸变化从8.7到4.0μm,坯体烧结密度变化从5.40到5.62 g/cm3。最佳的制备工艺为球磨时间为7.5 h,烧结温度为1100℃,其对应的电学性能分别为:电位梯度(V1mA)是542 V/mm,漏电流(IL)是2.88μA,非线性系数(α)是47。     

Er2O3 Doping Effect on Varistor Properties and Multiimpulse Stress Behavior of ZnO–PrO1.83–CoO–Cr2O3–Dy2O3 Ceramics

The Er₂O₃ doping effects on varistor properties and impulse aging behavior of the ZnO–PrO_1.83–CoO–Cr₂O₃–Dy₂O₃ ceramics were investigated in the range of 0–2.0 mol%. The nonlinear coefficient increased from 42 to 56 with an increase in the amount of Er₂O₃. The clamp voltage ratio (K) decreased with an increase in the amount of Er₂O₃. The varistors doped with 2.0 mol% in the amount of Er₂O₃ exhibited the best clamping characteristics, with K = 1.43–1.83 at an impulse current of 1–50 A. The varistors doped with 0.25 mol% in the amount of Er₂O₃ exhibited the strongest electrical stability, with the variation rate of the breakdown field of ?0.5%, the variation rate of the nonlinear coefficient of ?5.5%, and the variation rate of the leakage current of ?1.5% after applying 400 times at an impulse current of 400 A     

Al-doped ZnO varistors prepared by a two-step doping process

ABSTRACT

It is difficult to dope Al into main grains of ZnO varistor ceramics, especially for small doping amount. Generally, all raw materials including Al dopant are directly mixed together and sintered into ceramics. However, in this direct doping process, Al is apt to stay in grain boundaries, and almost does not enter grains. This does harm to the electrical properties of ZnO varistors. In this paper, we proposed a two-step doping process. Al₂O₃ powder was first mixed only with a part of the ZnO powder and pre-sintered. The pre-sintered powder was mixed with other additives such as Bi₂O₃ and the rest ZnO. Then ZnO varistor ceramics were prepared via solid state sintering processes. Results showed that two-step doped ZnO varistors exhibited improved electrical properties with a significant increased nonlinear coefficient and a great decreased leakage current compared to directly doped ones because more Al was incorporated into ZnO grains.     

TiO2体系对酸性红B的催化超声降解过程的影响

采用处理过的市售的锐钛型和金红石型纳米TiO2作为声催化剂,低功率的超声波作为激发源,研究了纳米TiO2对酸性红B催化超声降解过程的影响.结果表明:锐钛矿纳米TiO2和金红石型纳米TiO2对酸性红B有着不同的超声降解过程.锐钛型纳米TiO2以空穴氧化为主,使酸性红B脱色和降解过程同时进行,而金红石型纳米TiO2则以自由基氧化为主,是先脱色后降解.锐钛型纳米TiO2降解效果明显优于金红石型纳米TiO2.单纯超声照射下酸性红B没有明显的脱色和降解过程发生.因此,锐钛型纳米TiO2催化超声降解有机污染物的方法具有很好的应用前景.     

ZnO片式压敏电阻厚膜中Cr_2O_3含量的优化(英文)

研究三氧化二铬(Cr2O3)对氧化锌(ZnO)片式压敏电阻厚膜物相结构、微观结构和电性能的影响。X衍射分析表明:Cr2O3降低Bi4Ti3O12相的分解温度,并最终影响陶瓷厚膜的致密度、晶粒尺寸及电性能。当烧结温度为880℃时,Cr2O3摩尔(下同)掺量为0.3%的陶瓷厚膜能够得到良好性能:体积密度ρv=5.52g/cm3,晶界势垒Φb=0.116eV,非线性系数α=24.8。研究烧结温度与片式压敏电阻微观结构和电性能的关系,Cr2O3掺量为0.3%的片式压敏电阻在880℃烧结时,能够获得最佳电性能:压敏电压V1mA=25V,α=23.6,漏电流Il=2.8μA。该片式压敏电阻的低烧结温度和高非线性在工业生产中具有很大优势。     

功能型内墙真石漆的制备与性能研究

真石漆在内墙和外墙涂料中得到广泛应用。通过在内墙真石漆中添加掺杂Gd的纳米TiO2粉体,达到分解甲醛气体的目的,实现真石漆的功能化。同时对掺杂Gd的纳米TiO2粉体的加入量及其对真石漆的整体性能的影响进行了研究,获得了理想的效果。