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1、重庆大学硕士学位论文铌氧化物纳米材料的合成及性质研究姓名:张密超申请学位级别:硕士专业:材料物理与化学指导教师:胡陈果20090530重庆大学硕 +学位论文 中文摘要摘 要作为一种重要的氧化物材料,氧化铌(Nb205)在电子工业、陶瓷材料、光催化、 光学玻璃和航空航天工业中得到了广泛应用。近年来,随着新材料和纳米技术的 迅速发展,基于纳米级 Nb=05的相关材料在一些功能性陶瓷中的应用也越来越广 泛。因此,基于氧化物纳米材料的制备、性质及应用研究己成为一个迫切需要研 究的课题。本文研究了Nb205:Tb”和BaNb03纳米晶的性质及其制备方法。采用了一种低 温常压、操作简单、成本低廉、便于工业
2、化推广的制备新方法一复合氢氧化物媒 介法 (Composite-Hydroxide-Mediated, CHM)。利用该方法对氧化铌进行铽掺杂后, 制备了一种新型的晶体材料一鸟巢状 Nb=05: Tb3+微球。通过 X射线衍射 (XRD)和场发射扫描电子显微镜(FnSEM)的表征,发现它为单相且为单斜结构,具有独特的分等级鸟巢形状,平均尺寸为lima。对Nb205:Tb”的光学性质研究表明, 铽的掺杂使得氧化铌的发光更为显著,用535nm的激发波长去激发,发现在613nm 处有一个强度很强的发射峰,这表明所合成的Nb205:Tb3+样品作为红色荧光粉可 在发光系统和光器件方面有重要应用。文章同
3、时探讨了复合氢氧化物媒介法制备纳米级(平均粒径为1100nm的超细 粉末 )BaNb03粉末的最佳工艺条件,研究了反应时间对形成 BaNb03纳米晶粒径的 影响,以及基于BaNb03纳米晶的湿敏性质。通过XRD、FE-SEM、TEM以及U、,-Vis 的表征,发现其颗粒均匀,形貌规则,尺寸平均为50-200nm,且粒径随着生长时 间的延长而减小。利用该纳米颗粒做成的膜电极具有良好的湿敏特性,电极电阻 随湿度变化而剧烈变化。伴随着相对湿度从10增加到80,电极电阻从9324 MI) 变化到22 MQ,当相对湿度从20增加到60时,响应时间和恢复时间分别为12 秒和 32秒,这个结果表明铌酸钡纳米
4、颗粒在高灵敏的环境监测和湿度控制电子器 件领域有着重要的应用。最后,用离子导电模型解释了该湿敏传感器的湿敏机理。关键词: CHM法,铽掺杂氧化铌,光致发光,铌酸钡,湿敏重庆大学硕士学位论文 英文摘要AB STRACTAs a valuable oxide material , niobium oxide(NbEOs)possess promising applications in electron industry , ceramcis materials , photocatalytic , optical glasse , aviation industry and SO on In r
5、ecent years,晰tll the rapid development of the new materials and nanotechnology , it is found that the related materials based llano niobiumoxide m205)has been widely applied in the areas of functional ceramcis So theresearch of synthesize , property and application of oxide nanomaterials is anintere
6、sting subjectIn this paper , we developed a novel simple method to prepare Nb20s : Tb3+ microstructure and BaNb03 nanocrystal using the composi鼬 ydroxide-mediated(CHM)method , which is a new strategy that provides a one-step , convenient , low-cost , nontoxic and the method Was suitable for large-sc
7、ale preparation As a new kind of crystal materials , the nestlike microsphere Nb20s : Zb3+was synthesized by dopingniobium oxide(Nt , 20s) with some terbium (Tb) element usingcomposite-hydroxide-mediated(CHM)method The obtained sample exhibits a unique geometrical shape , and they were characterized
8、 by X-ray diffraction(XRD)and field emission scanning electron microscopy(FE-SEM) XRD and SEM show that the Nb20s : Tbj十 particles is singl唧 hase with the monoclinic structure , average crystal sizearound l lxm The research of the luminescence of the Tb3十 ions in the Nb205 latticeindicates that the
9、terbium(Tb)element we doped make the luminescence of the niobiumoxide(Nb205)crystal more salience, and there is a strong emission peak at 6 1 3 11111when we use wavelengh of 53 5 nnl to excitated , which indicates that the Nb20s ; Tb3+ microstructure Can be used as a promising phosphor for red lumin
10、escent display systems and lighting devices At the same time , we study the best technics conditions of the BaNb03nanocrysstal powder using composite-hydroxide-mediated(CHM)method , and westudy the effect of the reaction time to grain size of BaNb03 nanocrysstal , the humiditysensitivity based on Ba
11、Nb03 nanocrysstal The products were characterized by X-raydiffraction(XRD) , field emission scanning electron microscopy(FE-SEM) ,transmission electron microscopy(TEM)and UVWis analysis , the results indicates that the morphology of sample Was regulation and homogeneous , the average size of thenano
12、paticles is found to be very small, about 5m-200nm and as the reaction time WasII重庆大学硕十学位论文 英文摘要prolong the grain size diminution Humidity sensors based on BaNb03 nanocubes、 )l恤fabricated,nle responsiveness to humidity for static and dynamic testing proved theultrasensitive properties of the sensors
13、 m resistance changed from 932 4 MQ to 2 2MQ as the relative humidity(Rrt)increases from 1 0 to 80 The response-time and recovery-time of the resistance is 12s and 32s versus the changes of relative humidity from 20 to 60 These results indicate promising applications of BaNb03 nanocubesin a hie蛐 y s
14、ensitive environmental monitoring and humidity controlled electronic device At last , we discuss the sensing principles of the humidity sensor by ionicconduction model Keywords : CHM method,Tb doping niobium oxide, Photoluminescence, Bariumniobate, Humidity sensitivityIIl学位论文独创性声明本 人 声 明 所 呈 交 的 165
15、C)常压下制备单一氧化物或者复合氧化物的方法,制备过程中不需要使用有机溶剂或者表面活性剂。该方重庆大学硕士学位论文 2铽掺杂氧化铌复合材料的研究法除了具有液相法的优点外,还具有合成温度低、高纯、组成精确、操作简单、 成本低廉等许多优点。作为制备纳米氧化物的又一种新方法,复合氢氧化物媒介法 (CHM法 )于 2006 年首次在Nano Letters上报道152。531。复合氢氧化物媒介法是以熔融的无水氢氧化钠 和氢氧化钾为反应溶剂取代传统的溶剂法中的水或有机溶剂,以廉价的金属盐类 和金属氧化物为反应物。通常金属盐类(A源)主要包括硝酸盐、氯化物、碳酸盐和 醋酸盐等;金属氧化物 (B源 )则需要与目标产物中相应元素的化合价相一致。2 2 1实验过程用CHM法制备铽掺杂氧化铌晶体的主要流程如图21所示:按照515:485