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1.
YFeO3复合氧化物半导体材料的制备,掺杂和气敏性能研究   总被引:4,自引:0,他引:4  
用化学共沉淀法制备了YFeO3及其掺锌固溶体Y1-xZnxFeO3气敏材料,并对其制备条件、相结构、电导和气敏性能进行了研究。结果表明:Fe与Y物质的量比为1:1,850℃以上热处理一定时间可得钙钛矿结构的纯相YFeO3;电导测量显示,该系列材料呈p型半导体导电行为,且固溶体导电优于纯相。Y0.94Zn0.06FeO3电导突变温度400℃,较纯相YFeO3低70℃,900℃下热处理4h所得微粉制作  相似文献   

2.
采用固相反应法在900℃下制备出具有烧绿石结构的莳地导体气敏材料Cd2Nb2O7,研究了制备条件对产物物相和气敏性能的影响,探讨了高温固相反应机理。电导测试表明:Cd2Nb2O7是一种典型的表面电阻控制型半导体材料;而气敏测试表明:Cd2Nb2O7对乙醇具有较高的灵敏度、较好的选择性以及快的响应恢复速度。  相似文献   

3.
测试分析了La0 .8Sr0 .2 MnO3 材料的电导温度特性 ,发现电导随温度变化可以分成两个区域 :在 2 0 0~70 0℃ ,材料表现为半导体导电 ,此时材料的导电性能主要是由小极化子导电决定 ;在 70 0~ 10 0 0℃ ,材料呈现出金属导电 ,这是由于温度的升高 ,电子获得足够大的能量后由局域态变为自由态或准自由态  相似文献   

4.
利用简单的一步水热法成功制备了α-MoO3纳米带,之后采用光照法将Ag纳米粒子负载于α-MoO3纳米带表面,制备了Ag/MoO3纳米带复合材料.将制备的Ag/MoO3纳米带制备成气敏元件,测试了对三乙胺气体的气敏性能.结果表明,在温度170℃时,Ag/MoO3纳米带复合材料对三乙胺气体表现出良好的气敏性能,与纯相MoO...  相似文献   

5.
在100℃以下制备了一系列Ba0.9Sr0.1Ti1-xNdxO3固溶体纳米粉末(0≤x≤0.1),TEM观察粒子为均匀球形,平均粒径70 nm.制陶实验发现材料的室温介电常数达86000,比BaTiO3纯相提高近30倍,纳米粉体的烧结温度为1 150℃,比传统微米级粉体的烧结温度降低200℃.  相似文献   

6.
以尿素为沉淀剂,基于溶剂热法制备出具有特殊三维结构的纳米ZnO,并通过改变Ag的掺杂量制备乙醇气敏材料.利用XRD和SEM对所得产物的晶体结构及微观形貌进行表征, 采用静态配气法对制得的气敏元件进行性能检测.实验结果表明:与纯3D-ZnO相比,掺杂Ag可以有效地改善三维ZnO材料对乙醇气体的气敏性能.且当Ag掺杂质量分数为1.5 % 时,气敏元件对体积分数0.1%乙醇气体的响应值达31.61,工作温度由350℃降至200℃,同时响应/恢复时间缩短至10s/10s且乙醇选择性提高.  相似文献   

7.
ZnO—CdO二元体系的导电机制和气敏效应   总被引:1,自引:0,他引:1  
采用化学共沉淀与固相反应相结合的方法,合成了一系列不同Zn/Cd比氧化物粉料。研究了不同Zn/Cd比对相结构,电导与气敏性能的影响。没有发现Zn,Cd氧化物形成明显的置换固溶体或第三相,但存在间隙固溶体现象。  相似文献   

8.
用粉末溅射方法制备了体掺杂型SnO2 :Pt薄膜和表面层掺杂SnO2 /SnO2 :Pt双层膜 .实验结果表明 ,由室温至 2 0 0℃ ,这两种薄膜对CO气体均显示了较高的灵敏度和选择性 .单层膜厚度和双层膜导电层及气敏层厚度对灵敏度有明显的影响 .通过对掺杂单层膜和双层膜气敏特性的比较 ,对粉末溅射SnO2薄膜的气敏响应机理进行了探讨 .  相似文献   

9.
以二甲苯为油相 ,氧氯化锆、氯化钇和氯化铝的混合水溶液为水相 ,聚氧乙烯失水山梨醇单油酸酯为表面活性剂 ,采用溶胶 -乳状液 -凝胶法合成了掺杂Al2 O3的Y -TZP超细粉末 .通过热重 (TG)、差热 (DTA)、XRD ,分析了由凝胶粉末热解至Y -TZP粉末的转变过程 .用TEM观察了粉末的形貌和分散状态 .探讨了Y -TZP粉末形成和生长过程 .实验表明 ,约在 50 0℃ ,凝胶转变为Y -TZP固溶体 ;在 550℃下焙烧制备的Y -TZP粉末粒径为 8~ 1 0nm ;在 1 1 0 0℃下所得烧结体的相对密度达 96% ;粉末在高温下能保持很高的四方相含量  相似文献   

10.
研究了掺Mn对LaCrO3材料晶体结构和导电性能的影响及Mn离子的作用机制 .实验发现 :①LaCr1 -xMnxO3(0≤x≤ 1 ) 为正交钙钛矿结构 ,且随Mn含量的增多 ,材料晶格面间距逐渐增大 .②LaCr1 -xMnxO3固溶体在x =0 .1时电阻率异常增高 3个数量级 ,且随x的增大 ,电阻率逐渐下降 .应用缺陷化学理论对LaCrO3中掺Mn的电荷补偿过程进行了分析 ,揭示了过渡金属Mn对LaCrO3固溶体导电性能的作用机制  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

18.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

19.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

20.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

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