Nonlinear Electrical Properties of SnO2—LiO—Nb2O5 Varistor System

The electrical properties of (Nb,Li)-doped SnO2 ceramics as a new varistor material were investigated.The sample 97.95% SnO20.50%Li2O0.05%Nb2O5( mol fraction)sintered at 1450℃ possess the highest density(p=6.77g/cm^3) and nonlinear electrical coefficient(α=11.6).The substitution of Sn^4 with Li^ increases the concentration of oxygen vacancies,together with the formation of solid solution ,which will increase the sintering rate greatly and decrease the optimized sintering temperature.The substitution of Sn^4 with Li^ and the variation of temperature play very important effects on the densities,dielectric constant,nonlinear electrical properties and other characteristics of the samples.The properties of the grain boundary barrier and the microstructural characteristics were investigated to ensure the effect of the dopants and the temperature.A grain boundary defect barrier model was used to illustrate the grain boundary barriers formation in SnO2-Li2O-Nb2O5 varistors.     

Sb掺杂对ZnO-V2O5多元系压敏电阻的影响

本文研究了V/Sb预合成粉、SbVO4和Sb2O3等三种不同形式的Sb掺杂对ZnO-V2O5基压敏陶瓷结构和性能的影响.化学计量比不变情况下,上述Sb掺杂方式的改变,使烧结过程中Sb3 离子在陶瓷样品中的浓度上升,促进Zn7Sb2O12型尖晶石相形成,材料晶粒随之细化.同时材料的压敏电压出现大幅上升,而非线性系数和漏电流密度受Sb掺杂形式的变化影响不大.Sb以V/Sb预合成粉进行掺杂可以获得较大尺寸的晶粒,有利于材料在低压方面的应用.     

Improvement of electrical properties of V2O5 modified ZnO ceramics by Mn-doping for varistor applications

The dependence of microstructure, electrical properties, dielectric characteristics, and stability of conduction characteristics in ternary ZnO–V₂O₅–Mn₃O₄ system on the amount of Mn₃O₄ present in them was investigated. For all compositions studied, the microstructure of the ternary ZnO–V₂O₅–Mn₃O₄ system consisted of mainly ZnO grains and Zn₃(VO₄)₂ as a secondary phase. The incorporation of Mn₃O₄ to the binary ZnO–V₂O₅ system was found to restrict abnormal grain growth of ZnO. The breakdown field in the electric field–current density characteristics increased from 175 to 4,635 V/cm with the increase of Mn₃O₄ amount. The ternary system doped with 0.5 mol% Mn₃O₄ exhibited the highest non-ohmic properties, in which the non-ohmic coefficient is 22.4 and the leakage current density is 0.22 mA/cm². Furthermore, the sample doped with 0.5 mol% Mn₃O₄ was found to possess 0.43 × 10¹⁸/cm³ in donor density and 2.66 eV in barrier height.     

Type Inversion and Certain Physical Properties of Spray Pyrolysed SnO::A1Films for Novel Transparent Electronics Applications

Aluminium doped tin oxide films have been deposited onto glass substrates by using a simplified and low cost spray pyrolysis technique.The Al doping level varies between 0 and 30 at.%in the step of 5 at.%.The resistivity(ρ) is the minimum(0.38 Ω cm) for 20 at.%of Al doping.The possible mechanism behind the phenomenal zig-zag variation in resistivity with respect to Al doping is discussed in detail.The nature of conductivity changes from n-type to p-type when the Al doping level is 10 at.%.The results show that20 at.%is the optimum doping level for good quality p-type SnO_2:AI films suitable for transparent electronic devices.     

Co2O3掺杂对SnO2-Ni2O3-Nb2O5系压敏材料性能的影响

研究并分析了Ni^2＋掺杂和Co^2＋掺杂对SnO2压敏电阻致密度和电学非线性性能的影响。研究了掺Co^3＋对Sno2-Ni2O3-Nb2O5压敏材料性能的影响。实验结果表明，Co2O3在高温下可转变为CoO。Co^2＋的掺入不仅能够增大Sno2-Ni2O3-Nb2O5材料的质量密度，而且在线性系数，在较大程度上提高了Sno2-Ni2O3-Nb2O5压敏材料的性能。     

Dependence of La2O3 content on the nonlinear electrical behaviour of ZnO, CoO and Ta2O5 doped SnO2 varistors

The effects of La₂O₃ on the properties of (Zn, Co, Ta) doped SnO₂ varistors were investigated in this study. The samples with different La₂O₃ concentrations were sintered at 1400 °C for 2 h and their properties were characterized by XRD, SEM, I-V and impedance spectroscopy. The grain size was found to decrease from 13 μm to 9 μm with increasing La₂O₃ content. The addition of rare earth element leads to increase the nonlinear coefficient and the breakdown voltage. The enhancement was expected to arise from the possible segregation of lanthanide ion due to its larger ionic radius to the grain boundaries, thereby modifying its electrical characteristics. Furthermore, the dopants such as La may help in the adsorption of O′ to O″ at the grain boundaries characteristics.     

ZnO-V2O5-MnO2中压体系压敏电阻的微观组织和电学性能

研究了中压体系ZnO-V2O5 -MnO2 (ZVM)压敏电阻的微观组织和电学性能.结果表明,MnO2含量增加有利于细化ZVM陶瓷晶粒,改善电性能,提高压敏电压;提高烧结温度可以促进ZVM陶瓷晶体生长,改善致密度,降低压敏电压,提高非线性系数.中压体系ZVM陶瓷可以通过控制MnO2含量以及烧结温度获得.     

Nonlinear current-voltage properties and accelerated aging behavior of ZPCCL-based varistors with sintering temperature

The nonlinear electrical properties and accelerated aging behavior of the varistors, which are composed of ZnO-Pr₆O₁₁-CoO-Cr₂O₃-La₂O₃ (ZPCCL)-based ceramics, were investigated for different sintering temperatures. The increase of sintering temperature led to more densified ceramics, whereas it decreased the nonlinear properties and varistor voltage. The highest nonlinearity of varistors was obtained from sintering temperature of 1240 °C, in which the nonlinear coefficient is 79.4 and the leakage current is 0.3 μA. However, the highest stability of varistors was obtained from sintering temperature of 1260 °C, in which the %ΔV_1 mA is + 1.9%, the %Δα is − 10.6%, and the %ΔI_L is + 20% for stress state of 95 V_1 mA/150 °C/24 h.     

Luminescent properties of vanadium-doped SnO2 nanoparticles

This paper reports the influence of doping degree and annealing temperature on XRD, Raman, EPR and PL spectra of Sn_1−xV_xO₂ nanoparticles with x = 0, 0.01 and 0.05 annealed at 600 and 800 °C. XRD studies reveal a tetragonal rutile crystalline phases of tin oxide, while the formation of V₂O₅ secondary phase was evidenced for all doped nanoparticles only by Raman scattering. In function of the doping degree and annealing temperature, from EPR spectroscopy was evidenced the presence of three different positions for V⁴⁺ ions in the samples: isolated ions disposed on the nanoparticles surface, ions which are coupled by dipolar or exchange interactions and cluster ions. The luminescence emissions associated with oxygen vacancies and structural defects are influenced by doping degree and annealing temperature and could be correlated with the crystallite size determined from XRD patterns.     

Effect of sintering temperature on microstructure and electrical properties of ZVMCDN ceramics

The microstructure and electrical properties of ZnO-V₂O₅-MnO₂-Co₃O₄-Dy₂O₃-Nb₂O₅ (ZVMCDN) ceramics were investigated in accordance with sintering temperature (850-950 °C). The microstructure of the samples consisted of mainly ZnO grain as a main phase, and Zn₃(VO₄)₂, ZnV₂O₄, and DyVO₄ as the minor secondary phases. The sintered density decreased from 5.69 to 5.52 g/cm³ due to the volatility of V₂O₅ in accordance with increasing sintering temperature. The maximum nonlinear coefficient (57) was obtained at 925 °C. The donor concentration increased from 1.15 × 10¹⁸/cm³ to 11.1 × 10¹⁸/cm³ in accordance with increasing sintering temperature and the barrier height exhibited the maximum value (1.03 eV) at 925 °C.     

Optical properties of SnO2:F films deposited by atmospheric pressure CVD

Atmospheric pressure chemical vapor deposition (APCVD) system, designed for the deposition of F-doped SnO₂ thin films, is compatible with industrial requirements such as high process speed, scaling to wide substrate widths and low costs. Precise method for measuring the optical absorptance in the spectral range 300–1700 nm combines transmittance, reflectance and photothermal deflection (PDS) spectra measured on the same spot of the sample immersed in the transparent liquid with a relatively high index of refraction. The effects of the film thickness, doping gas addition and the susceptor temperature on the optical absorptance and electrical resistivity of the TCO films are assessed. We show that the doping gas concentration and the susceptor temperature influence both the incorporation ratio of dopants into SnO₂ film as well as the defect concentration. The SnO₂ films growth at optimum APCVD conditions have thickness 0.7 µm, average surface roughness about 40 nm, sheet electrical resistance 10 Ω/sq and the optical absorption 1% at 500 nm and about 5% at 1000 nm.     

Structural, electrical and optical characteristics of SnO2:Sb thin films by ultrasonic spray pyrolysis

Antimony-doped tin oxide (SnO₂:Sb) thin films were fabricated by an ultrasonic spray pyrolysis method. The effect of antimony doping on the structural, electrical and optical properties of tin oxide thin films were investigated. Tin(II) chloride dehydrate (SnCl₂·2H₂O) and antimony(III) chloride (SbCl₃) were used as a host and a dopant precursor. X-ray diffraction analysis showed that the non-doped SnO₂ thin film had a preferred (211) orientation, but as the Sb-doping concentration increased, a preferred (200) orientation was observed. Scanning electron microscopy studies indicated that the polyhedron-like grains observed for the non-doped SnO₂ thin films became rounder and decreased in size with the Sb-doping concentration. The lowest resistivity (about 8.4 × 10^− 4 Ω·cm) was obtained for the 3 at.% Sb-doped films. Antimony-doping led to an increase in the carrier concentration and a decrease in Hall mobility. The transmittance level in the near infrared region was lowered with the Sb-doping concentration.     

Electrical characterization of Ta2O5 films deposited by laser reactive ablation of metallic Ta

Tantalum oxide films have been deposited by 355 nm pulsed laser ablation of metallic Ta target in O₃/O₂ ambient. The structure and the composition of as-deposited and annealed films were examined by X-ray diffraction and Fourier transform infrared spectroscopy. The measurements of the current–voltage and capacitance–voltage characteristics of the Al/Ta₂O₅/Si capacitors were performed to reveal the electrical properties of the Ta₂O₅ films. The effects of annealing temperature on the characteristics of thin films have been studied. The results suggest that the films annealed above 700°C have the structure of orthorhombic β-Ta₂O₅, thc annealing treatment at high temperature decreases the bulk trap charge, the border trap, and the interface trap densities of as-deposited films, and improves significantly the dielectric and electrical properties of Ta₂O₅ film.     

P型SnO TFTs制备及其电学性能研究

采用直流磁控溅射结合光刻工艺,在室温下制备了p型SnO薄膜及薄膜晶体管器件。研究了直流磁控制备过程中的关键工艺问题。研究发现预溅射5 min、氧气比例为13%、生长压强为0.96 Pa、200℃退火1.5 h可制备高开关比的p型SnO薄膜晶体管。器件开关比可达到6.2×10³,亚阈值摆幅为9.96 V·dec^-1。通过延长退火时间至2 h,可以大幅提高线性区迁移率至1.61 cm²·V^-1·S^-1,且亚阈值摆幅仅增大了0.54 V·dec^-1。通过延长预溅射时间至8 min,可以大幅提高p型SnO薄膜晶体管的载流子迁移率,器件线性区迁移率为5.25 cm²·V^-1·S^-1,饱和区迁移率为0.43 cm²·V^-1·S^-1。     

Facile Synthesis of SnO2 Nanotube Arrays by Using ZnO Nanorod Arrays as Sacrificial Templates

SnO2 nanotube arrays have been synthesized by means of a simple and low-cost method. The ZnO nanorod arrays prepared by aqueous chemical growth method were used as templates. By liquid phase deposition, SnO2 nanotubes were obtained with proper deposition time. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used to characterize the morphologies and structures of the products, and the formation mechanism was discussed according to the experimental results.     

B2O3和Al2O3共同掺杂ZnO压敏陶瓷的性能

研究了B₂O₃(B)和Al₂O₃(Al)共掺杂对ZnO压敏陶瓷电学性能和微观结构的影响。结果表明,共掺杂B和Al的ZnO压敏陶瓷,具有低泄漏电流、高非线性和低剩余电压等优良电性能。B和Al的掺杂率为3.0%(摩尔分数)和0.015%(摩尔分数)的ZnO压敏陶瓷,其最佳样品的电参数为：击穿电压E_{1 mA}＝475 V/mm;泄漏电流J_L=0.16 μA/cm²;非线性系数α=106;剩余电压比K = 1.57。     

铌对(Y,Nb)掺杂的二氧化钛压敏-电容性能的影响

研究了铌对(Y,Nb)掺杂的二氧化钛压敏-电容性能的影响.研究中发现掺入0.10mol%Nb2O5的样品显示出最低的视在电场(EB=8.8V/mm)、最高的非线性常数(α=7.0)以及最高的相对介电常数(εr=7.6×104),与样品的晶界缺陷势垒特性、电容和电阻的频谱特性相一致.样品的性能变化可用Nb5+对Ti4+的掺杂取代和该取代存在的饱和值来解释.