低压双功能TiO2压敏陶瓷的研究

采用一次烧成工艺制备了具有电容性和压敏性双功能TiO2陶瓷.考察了Nb2O5施主掺杂对TiO2压敏陶瓷的显微结构、介电性能和压敏性能的影响.结果表明随Nb2O5掺杂量的增加,样品的晶粒粒径变大、晶界层变薄;压敏电压V1mA减小、非线性系数α和介电常数ε增大.当Nb2O5掺杂量为2 mol%时,TiO2压敏陶瓷有较好的压敏特性ε=22 000、V1mA=2.8 V和α=3.8.     

复合纳米添加法制备ZnO压敏电阻器

提出了一种利用复合纳米添加剂改善ZnO压敏电阻的晶界效应和微观特性，以获得高性能ZnO电阻片的方案，并通过化学共沉淀法制备了多元复合纳米添加剂。实验分析表明，此方案能提高通流50％以上，并能显著改善器件的微观均一性，制得的复合添加剂选择性好，易于实现工业化生产。     

籽晶法制备低压ZnO压敏电阻器

研究了ＺｎＯ籽晶粒度、掺入量及其制备方法对压敏电压的影响。实验结果表明：掺入适量粒度合适的籽晶，勿需在高温下长时间烧结，也可制成压敏电压较低，漏电流较小的ＺｎＯ压敏电阻器。     

Monolithic Device with Dual Capacitor and Varistor Functions

Protective devices are needed in electronic systems to protect against voltage surges. In this paper, a monolithic device incorporating both the functions of a capacitor and a varistor is described. The device has a capacitance of 1 μF and a dissipation factor less than 0.05 between 1 and 100 kHz. At voltages greater than the threshold voltage, V₀, of about 15 volts, the device conducts a current, I, according to the power-law relation of varistors, I=AV^α. The nonlinearity index, α, is 11.4. In this device, the capacitor function protects against the lowamplitude and high-frequency transients while the varistor function protects against the high-amplitude voltage surges. Appropriate capacitor and varistor composition can be found to have similar sintering temperatures, allowing the fabrication of monolithic devices with a range of sintering temperatures between 900° and 1350°C.     

ZnO压敏陶瓷材料导纳谱的自动测试

阐述了ＺｎＯ压敏陶瓷材料导纳谱测试的原理和方法,重点介绍了作者组建的自动测试系统以及由该系统测得的某些ＺｎＯ压敏陶瓷试样的Ｄ～ｆ、Ｇ～Ｔ和Ｃ’～Ｃ”曲线。     

Improved dielectric properties in A′‐site nickel‐doped CaCu3Ti4O12 ceramics

The improved dielectric properties and voltage‐current nonlinearity of nickel‐doped CaCu₃Ti₄O₁₂ (CCNTO) ceramics prepared by solid‐state reaction were investigated. The approach of A′‐site Ni doping resulted in improved dielectric properties in the CaCu₃Ti₄O₁₂ (CCTO) system, with a dielectric constant ε′≈1.51×10⁵ and dielectric loss tanδ≈0.051 found for the sample with a Ni doping of 20% (CCNTO20) at room temperature and 1 kHz. The X‐ray photoelectron spectroscopy (XPS) analysis of the CCTO and the specimen with a Ni doping of 25% (CCNTO25) verified the co‐existence of Cu⁺/Cu²⁺ and Ti³⁺/Ti⁴⁺. A steady increase in ε′(f) and a slight increase in α observed upon initial Ni doping were ascribed to a more Cu‐rich phase in the intergranular phase caused by the Ni substitution in the grains. The low‐frequency relaxation leading to a distinct enhancement in ε′(f) beginning with CCNTO25 was confirmed to be a Maxwell‐Wagner‐type relaxation strongly affected by the Ni‐related phase with the formation of a core‐shell structure. The decrease of the dielectric loss was associated with the promoted densification of CCNTO and the increase of Cu vacancies, due to Ni doping on the Cu sites. In addition, the Ni dopant had a certain effect on tuning the current‐voltage characteristics of the CCTO ceramics. The present A′‐site Ni doping experiments demonstrate the extrinsic effect underlying the giant dielectric constant and provides a promising approach for developing practical applications.     

ZnO一玻璃系压敏电阻的微观结构

制备了ZnO一玻璃系压敏电阻．用SEM．TEM，Et’MA等微观分析手段研究TZnO-玻璃系压敏电阻的微观结构，相组成与元素分布。ZnO-玻璃系压敏电阻由ZnO主晶相、Zn7Sb，O12尖晶石相以及粒问相组成。L、。离子有较大部份已溶入ZnO晶粒内，而Mn离子只有少量进人zr、L)晶粒之表层．sb离子主要分布在粒间处。品界层厚度约为10～100mm．其成分与ZuO晶柱内成分基本相近。在一定的烧结温度下，粒间相中还生成了，Zn～B结晶相．该相的产生有利于增强压敏电阻的非线性特性。     

Processing of Novel Strontium Titanate-Based Thin-Film Varistors by Chemical Solution Deposition

Strontium titanate (SrTiO₃)-based multilayered film with varistor characteristics has successfully been fabricated by a chemical solution deposition (CSD) method. Homogeneous precursor solutions of SrTiO₃ and Nb:SrTiO₃ with long-term stability could be prepared by optimizing the reaction conditions among strontium ethoxide, titanium isopropoxide, and niobium ethoxide. Films were prepared using the precursor solutions on fused silica substrates at 700°C. Triple layered films with SrTiO₃/Nb:SrTiO₃/SrTiO₃ structure were also successfully crystallized on Pt/Ti/SiO₂/Si substrates at 700°C. The current–voltage ( I - V ) curve of the multilayered film was characteristic to varistors and the nonlinear coefficient α of the synthesized film was ∼3.0. The varistor voltages ( E _0.01) of 0.6-μm-thick film were 140 kV/cm for the forward direction and −120 kV/cm for the reverse direction, respectively, at room temperature.     

铌掺杂对Ce-Nb-TiO_2系压敏陶瓷结构与电性能的影响

研究了铌对Ce,Nb掺杂的二氧化钛压敏陶瓷结构和电性能的影响。结果表明,在1 350℃烧结条件下,掺入0.8%Nb2O5的样品具有优良的综合电性能,显示出低的压敏电压(U1mA=7.22V/mm)、高的非线性系数(α=5.76),是一种很有潜力的新型电容-压敏陶瓷材料。铌掺杂主要是Nb5+对Ti4+的掺杂取代,该掺杂存在一饱和值。Nb2O5在不同的掺杂浓度下,存在的形式和位置不同,同时与一些低熔点化合物相如Ce2Ti2(Si2O7)O4等相互作用,使得样品的电性能发生变化。     

Nb2O5掺杂对TiO2陶瓷性能的影响

在Nb2O5含量x为0.1～1.5%的范围内,研究了Nb2O5掺杂对TiO2压敏陶瓷电性能的影响.发现x＝0.7%的样品显示出最低的压敏电压(Eb=8.57V/mm )以及最高的相对介电常数2.385×104.分析认为Nb2O5掺杂的实质是Nb5 固溶于 TiO2中取代Ti4 使晶粒半导化,但掺杂量受晶格畸变作用有一定限制.