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稀土Ce对SnO2·Co2O3·Nb2O5压敏性能的影响 总被引:1,自引:0,他引:1
研究了掺Ce对SnO2·Co2O3·Nb2O5压敏电阻器性能的影响。研究发现Ce4+对Sn4+的取代能明显提高陶瓷的致密度,掺入x(CeO2)为0.05的陶瓷样品具有最高的密度(ρ=6.71g/cm3),最高的视在势垒电场(EB=413.6V/mm),最高的非线性系数(α=13.8),最高的势垒电压和最窄的势垒厚度。为了解释样品电学非线性性质的起源,该文提出了SnO2·Co2O3·Nb2O5·CeO2晶界缺陷势垒模型。同时,对该压敏电阻器进行了等效电路分析。试验测量与等效电路分析结果相符。 相似文献
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(Li,Nb)掺杂SnO_2压敏材料的电学非线性研究 总被引:2,自引:0,他引:2
研究了掺锂对 Sn O2 压敏电阻器性能的影响。研究发现 L i 对 Sn4 的取代能明显提高陶瓷的烧结速度和致密度 ,且能大幅度改善材料的电学非线性性能。掺入 x(L i2 CO3)为 1.0 %的陶瓷样品具有最高的密度 (ρ=6 .77g/ cm3)、最高的介电常数 (ε=185 1)、最低的视在势垒电场 (EB=6 8.86 V/ mm)和最高的非线性常数 (α=9.9)。对比发现 ,Na 由于具有较大的离子粒半径 ,其掺杂改性性能相对较差。提出了 Sn O2 · L i2 CO3· Nb2 O5晶界缺陷势垒模型 相似文献
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研究了TiO2掺杂对SnO2-Co2O3-Nb2O5系压敏陶瓷材料电学性能的影响。掺入x(TiO2)为1.00%的陶瓷样品具有最高的密度(r = 6.82 g/cm3),最高的视在势垒电场(EB= 476 V/mm),最高的非线性系数(a = 11.0),最小的相对介电常数。未掺杂的样品阻抗最大。随TiO2掺杂量的增加晶粒逐渐变小,晶粒尺寸的减小归因于未固溶于SnO2晶格而偏析在晶界上的TiO2阻碍相邻SnO2晶粒融合。为了解释SnO2-Co2O3-Nb2O5-TiO2系电学非线性性质的根源,对前人的晶界缺陷势垒模型进行了修正。 相似文献
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研究并分析了 Ni3+ 掺杂和 Co2 + 掺杂对 Sn O2 压敏电阻致密度和电学非线性性能的影响。研究了掺Mn2 +对 Sn O2 · Ni2 O3· Nb2 O5压敏材料性能的影响。发现 x(Mn CO3)为 0 .10 %时 ,压敏电阻具有最高的视在电场(EB=6 86 .89V/ m m)和最好的电学非线性性能 (α=12 .9)。样品的收缩率和致密度变化趋势不一致 ,这是因为样品的致密度是由收缩率和 Mn CO3的挥发量两因素共同决定的 相似文献
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(Ba,Co,Nb)掺杂SnO2压敏材料电学非线性的研究 总被引:2,自引:0,他引:2
通过对样品的伏安特性,晶界势垒的测量和分析,研究了BaCO3对新型(Co,Nb)掺杂SnO2压敏材料微观结构和电学性质的影响。晶界势垒高度测量表明,SnO2晶粒尺寸的迅速减小是压敏电压急剧增高的原因。对Ba含量增加引起SnO2晶粒减小的根源进行了解释。掺杂x(BaCO3)=0.4%的SnO2压敏电阻击穿电压为最小(140V/mm);掺杂x(BaCO3)-0.8%的SnO2压敏电阻具有最高非线性系数(α=19.6),最高的势垒电压(ψB=1.28eV)。 相似文献
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采用高温固相反应法制备了CaSi2O2N2:C e3+/Eu 2+荧光粉,研究了分别掺杂Ce3+、Eu2+及Ce3+/Eu2+共掺 杂时荧光粉 的发光特性。CaSi2O2N2:Ce3+在333 nm激发下得到宽波段的发射谱,发射峰 位于395nm,随着Ce3+浓度的增大,发 射波长出现明显的红移,猝灭浓度为1mol%。CaSi2O2N2:Eu2+在397nm激发下得到峰值位于540nm处的宽波段发射谱, 猝灭浓度为1mol%。对于Ca0.99-2xSi2O2N2:xCe 3+,xLi+,0.01Eu2+荧光粉,在333nm激发下,位于395nm处的发射峰十分微 弱,在540nm处有宽带发射,随着Ce3+浓度增大,位于540nm处的Eu2+的特征 发射显著增强。对于Ca0.98-ySi2O2N2: 0.01Ce3+,0.01Li+,yEu2+荧光粉,在激发光波长 为333nm,Eu2+浓度较低时,可以观察到两个发射带,峰值分 别位于395nm及540nm,随着Eu2+浓度增加,位于395nm的 发射强度一直减小,而540nm处的发射强度先增加后减小,猝灭浓 度为0.4mol%。证实了Ce3+,Eu2+之间发生了有效的能 量传递。计算出Ce 3+、Eu2+之间能量传递的效率ηT,在Eu2+浓 度为 1mol%时ηT趋于饱和,达到97.7%。通过计算,得到Ce3+ 与Eu2+之间的能量传递方式为电偶极-电偶极相互作用。 相似文献
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Wheatley R.W. Hennessy M.J. Hung Bin Zou 《Applied Superconductivity, IEEE Transactions on》1997,7(1):7-13
The temporal stability of trapped transport current in annular thin film Tl2Ba2CaCu2O8 (TBCCO) and YBa2Cu3O7 (YBCO) wafers has been accurately measured and has been found to be of suitable quality for the stringent requirements of nuclear magnetic resonance (NMR) magnets. No detectable decay, to the limit of the experimental apparatus (2*10-14 Ω), was detected in those wafers with transport current at or below the critical current density Jc. The critical current density, as previously determined from 12 μm meander lines, was confirmed in a wafer with a width of 1.9 cm. The profile of trapped magnetic field resulting from induced current was modeled in order to assess its effect on the uniformity of an NMR magnet 相似文献
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An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2-V2O5-Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 mol%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO2 makes the highest α value (α = 12.8), the lowest breakdown voltage V1mA (V1mA = 15.8 V/mm) and the highest grain boundary barrier ΦB (ΦB = 1.48 eV), which is remarkably superior to the TiO2-V2O5-Y2O3 varistor ceramics undoped with Ge and GeO2 and mono-doped with Ge or GeO2. The TiO2-V2O5-Y2O3-Ge-GeO2 ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties. 相似文献
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Aluminium oxide displays a very low tanδ at microwave frequencies. It also possesses a remarkably high thermal conductivity, ideal for heat dissipation in high power satellite filters. However, its temperature coefficient of the resonant frequency (τf) is approximately 60 ppm/K. It is shown that the application of a film of titanium oxide which has a Tf of opposite sign (45O ppm/K) produces a composite in which the τf can be tuned to be zero over a wide temperature range. The tanδ of the composite at zero Tf is 3.3×105 (Q=30000) at room temperature and at 10 GHz 相似文献
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Tajima K. Ohashi M. Shiraki K. Tateda M. Shibata S. 《Lightwave Technology, Journal of》1992,10(11):1532-1535
The Rayleigh scattering and infrared absorption losses of P2 O5-F-doped silica glass, which is a candidate material for ultra-low-loss optical fiber, were investigated experimentally. The Rayleigh scattering loss of 8.5 wt.% P2O5 and 0.3 wt.% F-doped SiO2 glass is found to be 0.8 times that of pure silica glass. It is also found that the infrared absorption property of P2O5-F-SiO2 glass is almost the same as that of pure silica glass. The minimum loss for the proposed composition is estimated to be 0.11 dB/km at 1.55 μm wavelength, and 0.21 dB/km at 1.3 μm wavelength 相似文献
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A low-loss polyimide-Ta2O5-SiO2 hybrid antiresonant reflecting optical waveguide (ARROW) is presented. The ARROW device was fabricated using both the organic and dielectric thin-film technologies. It consists of the fluorinated polyimide, tantalum pentoxide (Ta2O5), and silicon dioxide (SiO2) hybrid layers deposited on a Si substrate. For transverse electric polarized light, the propagation loss of the waveguide as low as 0.4 dB/cm was obtained at 1.31 μm. The propagation loss for transverse magnetic polarized light is 1.5 dB/cm. An ARROW waveguide fabricated using the polyimide-Ta2O5 -polyimide material system is also presented for comparison 相似文献
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Ebbers C.A. DeLoach L.D. Webb M. Eimerl D. Velsko S.P. Keszler D.A. 《Quantum Electronics, IEEE Journal of》1993,29(2):497-507
The harmonic generating properties of potassium lanthanum nitrate (KLN) and potassium cerium nitrate (KCN) are described. These crystals have much larger nonlinear coefficients than potassium dihydrogen phosphate (KDP) and are nearly noncritically phase matched at room temperature for Type I frequency doubling of 1.064-μm light, and for Type II doubling of light near 0.95 μm. Thus, these crystals are useful for generating blue-green light by frequency doubling high-power near-infrared lasers. The crystal growth of KLN and KCN are described by the three component phase diagrams. Crystallographic data for KCN that confirms its structural similarity to KLN are presented. The optical absorption spectra of the two materials are discussed, and the linear refractive indexes are given 相似文献
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The impact of various rapid thermal annealing used during the integration on the La2O3/HfO2 and HfO2/La2O3 stacks deposited by Atomic Layer deposition was analyzed. The consequences of lanthanum localization in such stacks on the evolution of the films during the rapid thermal annealing are investigated in term of morphology, crystalline structure, silicate formation and film homogeneity as a function of the depth. It appeared that the La2O3 location has an impact on the temperature of the quadratic phase formation which could be linked to the formation of SiOHfLa silicate and the resistance of the films to dissolution in HF 0.05 wt%. 相似文献