锑掺杂二氧化锡薄膜的导电机理及其理论电导率

归纳总结了锑掺杂二氧化锡(ATO)的导电机理。晶格的氧缺位、5价Sb杂质在SnO2禁带形成施主能级并向导带提供n型载流子是ATO导电的两种主要机理。从材料的电导率公式出发,定性分析了二氧化锡中掺杂锑的含量存在理论最佳值,根据已有模型计算证明了锑掺杂二氧化锡电导率存在理论上限。掺杂二氧化锡中锑的最佳理论含量为1.49%(质量百分数),锑掺杂二氧化锡理论电导率最高为0.217×104(Ω·cm)-1,氧空位对ATO电导率的贡献为0.1506×104(Ω·cm)-1。     

化学氧化法聚吡咯导电性能与导电机理

采用化学氧化法制备了导电聚吡咯(PPy).运用SEM和TEM表征了PPy的形貌,利用四探针技术测试了材料的电导率,对影响其电导率的因素进行了讨论,并对其导电机理进行研究.结果表明,氧化剂用量、反应温度、反应时间、掺杂剂的种类等对最终所得材料的导电性能及结构形态有较大的影响.以苯磺酸钠作掺杂剂,FeCl3/Py摩尔比为1.0,冰浴条件下,反应0.5h所得材料电导率最高,为58.82S/cm,其中以2-萘磺酸为掺杂剂所得PPy微观形貌呈现罕见的纤维状.电导率相对较高的PPy,说明其本身掺杂状况使它在氧化掺杂时随导带和价带间的能级差减小,禁带变窄,载流子移动阻力小;阴离子的掺杂和脱掺杂变得容易,因而电导率高.     

化学氧化法聚吡咯导电性能与导电机理

采用化学氧化法制备了导电聚吡咯(PPy).运用SEM和TEM表征了PPy的形貌,利用四探针技术测试了材料的电导率,对影响其电导率的因素进行了讨论,并对其导电机理进行研究.结果表明,氧化剂用量、反应温度、反应时间、掺杂剂的种类等对最终所得材料的导电性能及结构形态有较大的影响.以苯磺酸钠作掺杂剂,FeCl3/Py摩尔比为1.0,冰浴条件下,反应0.5h所得材料电导率最高,为58.82S/cm,其中以2-萘磺酸为掺杂剂所得PPy微观形貌呈现罕见的纤维状.电导率相对较高的PPy,说明其本身掺杂状况使它在氧化掺杂时随导带和价带间的能级差减小,禁带变窄,载流子移动阻力小;阴离子的掺杂和脱掺杂变得容易,因而电导率高.     

不同掺氮量的类金刚石薄膜的电导性能

研究了不同含氮量的类金刚石薄膜（DLC:N）的导电性能，发现随着氮含量的增加，薄膜的电导率增加较缓，当氮含量达到一定值（12.8at%)后，薄膜电导率反而随氮含量的继续增加而下降。将薄膜在300℃下退火30min，结果表明低参氮的薄膜退火后导电性能有了较大的提高，而高掺氮的薄膜退火后电导率有所下降。Raman和XPS光谱研究表明，当薄膜中的氮含量达到一定值后，在薄膜中会出现非导电（a-CNx）的成分，因此高掺杂的类金刚石薄膜的电导率下降。FTIR光谱表明，充当施主杂质中心的氮原子在薄膜退火过程中存在被“激活”的现象，从而提高了电导率。因此氮对高掺杂和低掺杂薄膜导电性能的影响是不同的。     

喷墨印刷沉积的PEDOT/PSS薄膜导电性能

利用压电喷墨印刷技术沉积了PEDOT/PSS有机导电薄膜,研究了退火温度和乙二醇掺杂对薄膜导电性能的影响。实验结果表明:未退火和退火温度为120,140,160℃时,薄膜表面平均粗糙度分别为8.15,4.10,3.36,2.66nm;乙二醇掺杂使导电激活能由未掺杂时的0.096eV减小为0.046eV;电导激活能减小表明PEDOT分子链从低电导率的卷曲构象向高电导率的伸展构象转变;此外,乙二醇掺杂促使PSS与PE-DOT/PSS分离,使团聚的PEDOT/PSS颗粒变小从而分散更均匀,降低了表面粗糙度。     

铜酚醛树脂导电油墨的研究

高性能导电油墨的开发是印制电子技术研究焦点之一。本文利用自制热固性酚醛树脂做联接剂,铜粉做导电填料来制备导电油墨。通过试验获得的最佳配方中各组分比例为:合成树脂组分中苯酚:甲醛溶液:氢氧化钠=1:(4-5):3,铜粉重量占固化后油墨总重的75%-80%。在此配比范围内,150℃加热固化后导电油墨的电阻率可以达到实际应用要求的100Ω/cm。     

Li_2CO_3掺杂对SnO_2基导电陶瓷结构及性能的影响

采用固相法制备了SnO_2导电陶瓷,研究了Li_2CO_3掺杂量对SnO_2导电陶瓷的导电性能和体积密度以及微观结构的影响。结果表明:Li_2CO_3的掺杂不改变SnO_2导电陶瓷的晶体结构,在一定的掺杂范围内有利于晶体的生长。随着Li_2CO_3掺杂量的增加,SnO_2导电陶瓷的电阻率先降低,然后升高;体积密度先增加然后减小。当烧结温度为1 350℃,Li_2CO_3掺杂量为质量分数0.7%时,SnO_2导电陶瓷的综合性能较好,体积密度为5.027 g/cm3,电阻率为5.638×10–3?·cm。     

定向排列石墨烯/丁苯橡胶复合材料的电热性能研究

采用石墨烯纳米片作为发热材料,水性丁苯橡胶为基体,制备了定向排列石墨烯/丁苯橡胶复合材料。探究了石墨烯的含量对该复合材料电导性能的影响,研究了电导性和电压对该复合材料的电热性能的影响。实验结果表明,该复合材料的电导率随石墨烯含量的增加而增加,当石墨烯质量分数为3%时,该复合材料的电导率为0.53 S/cm;该复合材料的电热性能随电导率和电压的增加而增加,当施加12 V的激励电压,电导率为0.53 S/cm的复合材料的加热饱和温度为88℃。     

用纳米银棒和颗粒制备高导电性油墨

研制了一种高导电性油墨。首先,分别以乙二醇和N,N-二甲基甲酰胺为还原剂,还原硝酸银溶液得到纳米银棒和纳米银球形颗粒。用纳米银棒和纳米银球形颗粒混合银粉、双酚A环氧树脂/酚醛树脂、丁酮等其他助剂配制导电油墨。研究了不同固化温度、固化时间对所制油墨导电性能的影响。结果表明,在150℃固化20 min该油墨印刷的导电图形具有很致密的表面结构和丰富的三维导电网络,其体积电阻率达3.6 10–6.cm。     

α-Si:H薄膜的制备及掺杂样品电导率

本文介绍了运用辉光分解硅烷法制备a-Si:H薄膜的基本原理、设备及工艺,采用不同的工艺条件制备了一系列不同的掺杂和本征a-Si:H薄膜,对掺杂样品的电导率进行了检测.结果表明,掺杂显著地提高了材料的电导率.     

Conductivity mechanisms of isotropic conductive adhesives (ICAs)

Isotropic conductive adhesives (ICAs) are usually composites of adhesive resins with conductive fillers (mainly silver flakes). The adhesive pastes before cure usually have low electrical conductivity. The conductive adhesives become highly conductive only after the adhesives are cured and solidified. The mechanisms of conductivity achievement in conductive adhesives were discussed. Experiments were carefully designed in order to determine the roles of adhesive shrinkage and silver (Ag) flake lubricant removal on adhesive conductivity achievement during cure. The conductivity establishment of the selected adhesive pastes and the cure shrinkage of the corresponding adhesive resins during cure were studied. Then conductivity developments of some metallic fillers and ICA pastes with external pressures were studied by using a specially designed test device. In addition, conductivity, resin cure shrinkage, and Ag flake lubricant behavior of an ICA which was cured at room temperature (25°C) were investigated. Based on the results, it was found that cure shrinkage of the resin, rather than lubricant removal, was the prerequisite for conductivity development of conductive adhesives. In addition, an explanation of how cure shrinkage could cause conductivity achievement of conductive adhesives during cure was proposed in this paper     

Direct imprint of conductive silver patterns using nanosilver particles and UV curable resin

The direct nanoimprinting of device patterns on functional resist has attracted increasing attention since it has the potential to extend nanoimprinting applications and improve productivity. Considerations of device-oriented functional resins are currently limited to optical or optoelectronic applications where the optical properties of the imprint resin can be selectively controlled. Either nanosilver particle dispersions or conductive polymers are candidate resins for the direct imprinting of electrode line patterns. In this paper, we describe direct ultraviolet (UV) imprinting using acrylate-based resin incorporating nanosilver colloid, with optimized post-imprinting steps involving heat treatment and wet etching. Resin mixtures with 40, 50, and 60 wt% of nanosilver loading were prepared, and UV imprinting was performed on the dispensed resin mixtures, followed by heat treatment to sinter the nanosilver particles and wet etching of the imprint residues. The pattern shrinkage that occurred during the post-imprinting steps reached 25–35%, and was strongly dependant on the nanosilver concentration. The electrical resistivity for 60 wt% Ag loading was roughly 2.5 times higher than that of bulk silver. In addition, surface texturing effects on the imprinted patterns were investigated using selective oxygen plasma etching.     

Dispersion, hybrid interconnection and heat dissipation properties of functionalized carbon nanotubes in epoxy composites for electrically conductive adhesives (ECAs)

Different types of MWNTs/epoxy composites were prepared with diglycidyl ether of bisphenol F (DGEBF) and bisphenol A (DGEBA) used as epoxy resins. MWNTs were functionalized to enhance the properties of epoxy composites by treatment with strong acids (acid-treated MWNTs, a-MWNTs) followed by m-phenylenediamine grafting (amine grafted MWNTs, m-MWNTs). Raw, a-, and m-MWNTs were dispersed in DGEBF or DGEBA to a concentration of 1 wt.%. X-ray photoelectron spectroscopy and thermogravimetric analysis verified the effectiveness of acid treatment and confirmed the amine-functionalization of the MWNTs. Scanning electron microscopy of the fracture surface of the epoxy matrix showed that chemical functionalization improves compatibility between the epoxy and MWNTs. Good dispersion of MWNTs leads to the improvement in coalescence and pull strength in the quad flat package (QFP) test. Further, the thermal conductivity of MWNTs/epoxy composites was higher than that of pure epoxy resins. In particular, the m-MWNT/epoxy composite has the best heat dissipation properties, due to the formation of an effective network for heat flow.     

提高小功率白光LED热特性的新方法

在传统直插式LED封装方法的基础上,提出了一种在环氧树脂中添加氮化硼(BN)填料的改进LED封装工艺。测量了BN填料质量分数与导热系数的关系,利用有限元分析软件ANSYS分析和实验测试了采用改进封装工艺φ5 mm白光LED的芯片结温、热阻等参数,并与传统封装方法的白光LED进行比较。结果表明:采用改进封装结构φ5 mm白光LED结温比传统封装方法下降4.5℃,热阻下降了17.8%,同时提高了初始光通量,降低了光衰。     

纳米阴离子导体离子导电性能的研究进展

介绍了纳米技术在氧离子导体和氟离子导体的制备及导电性能研究方面的应用。纳米尺度的氧化物在烧结过程中致密化温度可降低50～200℃,最终产物的晶粒尺寸可小于1μm,离子电导率较高,可达到10–1S·cm–1量级。纳米氟离子导体与传统粗晶氟离子导体相比,具有明显的纳米尺寸效应,导电激活能可降低30%,离子电导率可提高1～2个数量级。     

共沉淀-熔盐法制备六方磁铅石型钡铁氧体

以FeCl2·4H2O、FeCl3·6H2O、BaCl2·2H2O和氨水为原料,采用共沉淀–熔盐法制备了六方磁铅石型钡铁氧体。通过TGA-DTA,XRD及JDAW—2000B型振动样品磁强计等手段,研究了热处理制度对粉末的矿物组成及磁性能的影响。结果表明:当w(助熔剂)为10%时,在1000℃及还原性气氛下进行热处理,所得样品的单位质量饱和磁矩最大,达到1346A·m2·kg–1。     

Sr0.3Ba0.7Bi3.7La0.3Ti4O15铁电陶瓷的烧结及介电性能

采用两步烧结工艺制备Sr0.3Ba0.7Bi3.7La0.3Ti4O15铁电陶瓷,研究了烧结工艺对陶瓷的晶相和介电性能的影响。结果表明:适当提高最高温度、保温温度和保温时间可改善陶瓷的介电性能。当最高温度为1180～1200℃,在1050～1080℃保温5～15h时,其εr为238～262,tanδ小于10–2,σ为1.0×10–11～10–12S·m–1。该烧结工艺可减少铋的挥发,降低氧空位浓度,因而减弱了陶瓷的高温低频耗散现象。随着保温时间的增加,高温电导得到有效抑制,在1050℃保温15h样品的σ降低了一个数量级,在280℃时为5.2×10–9S·m–1。     

In2O3基甲醛传感器的研制

以sol-gel法制备的In2O3纳米材料为基体,采用La2O3作为掺杂剂,研制出甲醛传感器。结果表明:La2O3的掺杂可以明显提高元件对甲醛的灵敏度,在工作温度为145℃,(甲醛)为10×10–6时,元件表现出4倍的灵敏度,通过4A分子筛的修饰提高了元件的选择性。在为期90d的追踪实验中发现元件的灵敏度变化小于10%,元件在(甲醛)为50×10–6时,响应、恢复时间分别为8s和30s。     

甲酰胺对P_2O_(5-)SiO_2系玻璃导电性能的影响

利用sol-gel法制备了P2O5-SiO2系质子导电玻璃。借助扫描电镜、电导率测试等手段,研究了甲酰胺对玻璃的结构和导电性能的影响。结果表明,甲酰胺能使玻璃形成微孔结构,提高质子电导率。在30℃,RH为50%的条件下,玻璃的电导率为10–3~10–2 S·cm–1。     

CdO对In2O3电导和气敏性能的影响

为探索新型CdO-In2O3材料的气敏性能,用化学共沉淀法制备了CdO掺杂的In2O3微粉,研究了CdO掺杂对In2O3电导和气敏效应的影响。结果表明CdO和In2O3间能形成有限固溶体In2-CdxO3(0≤x≤0.02);In1.98Cd0.02O3x的电导比纯In2O3小得多;900℃下热处理4h所得的x(CdO)为2%的In2O3传感器在183℃工作温度下,对45μmol·L–1C2H5OH的灵敏度达276、响应–恢复时间只有3s和180s。有望开发为一类新型酒敏材料。