锰掺杂诱导正交相SnO2的生长行为
2021-12-22
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第19卷第5期 2013年10月 上洛戈 报(自然科学版) V01.19 NO.5 Oct.2013 JOURNAL OF SHANGHAI UNIVERSITY(NATURAL SCIENCE) DOI:10.3969/j.issn.1007—2861.2013.05.004 锰掺杂诱导正交相SnO2的生长行为 王利军, 陈 琛, 刘延雨, 陈志文 (上海大学环境与化学工程学院射线应用研究所,上海200444) 摘要: 通过一种简单的共沉淀方法制备了Mn掺杂二氧化锡(SnO2)颗粒,对前驱体在不同温度下热处理,并通 过x射线衍射fx—ray difraction,XRD) ̄tl高分辨电子显微学(high—resolution transmission electron microscopy, HRTEM)对样品的微纳米结构进行了表征.结果表明:样品中除了四方相SnO2外,还存在正交相SnO2.XRD测 试结果显示,随着退火温度的增加,正交相Sn02的峰强减弱,四方相的峰强增加.HRTEM分析表明:样品中可 以同时找到四方相和正交相SnO2的晶格像,进一步证实了正交相SnO2的存在.Mn掺杂Sn02后,Mn离子进入 SnO2晶胞,替代了Sn离子,因此引起晶格扭曲畸变,对正交相SnO2的形成起着重要的作用. 关键词:二氧化锡(SnO2);四方相;正交相;晶格畸变;微纳米结构 中图分类号:O 649.1 文献标志码:A 文章编号:1007-2861f2013)05—459—06 Growth Behavior of Orthorhombic SnO2 Induced by Mn-Doped SnO2 WANG Li—jun, CHEN Chen,LIU Yan-yu,CHEN Zhi—wen (Applied Radiation Institute,School of Environmental and Chemical Engineering,Shanghai University Shanghai 200444,China) Abstract:Tin dioxide(SnO2)is an n—type semiconductor material with tetragonal rutile crystal structure under normal conditions and displays many interesting physical and chemical properties.Another form of SnO2 with an orthorhombic crystal structure is known to be stable only at high pressures and temperatures.However, there are limited reports on effects of Mn—doped tetragonal phase SnO2 on micro/nano8tructured characteristics. In this article,micro/nanostructures of Mn—doped tetragonal phase SnO2 have been successfully prepared with a chemical co-precipitation method.The micro/nanostructural evolution of Mn—doped tetragonal phase SnO2 under diierent heat treatment temperatures ifS evaluated with X—ray diiractifon fXRD1 and a high—resolution transmission electron microscopy(HRTEM).It is surprisingly found that the orthorhombic phase SnO2 is formed in Mn—doped tetragonal phase SnO2.The obvious diffraction peaks and clear lattice fringes confirm that the orthorhombic phase SnO2 nanocrystals evidently exist in Mn—doped SnO2 samples.Experimental results indicate that the XRD peak intensities and crystal planes of the orthorhombic phase SnO2 decrease with increasing of heat treatment temperatures.Formation of orthorhombic phase Sn02 iS attributed to the lattice distortion of tetragonal phase SnO2 due to the Mn—doped tetragonal phase SnO2. Key words:tin dioxide(SnO2);tetragonal;orthorhombic;lattice distortion;micro-nanostructure 二氧化锡(SnO2)是一种具有广泛应有价值的功能 材料,且是一种重要的n型宽禁带氧化物半导体材 传感器[7—8]、电极材料[9_103、有机化合物的氧化催化  ̄lj[11]、光电设备[12_l3]等许多领域得到了广泛的应用. 料(300 K时,Eg=3.64 eV),具有良好的透明性和化学 稳定性性能,因此在过去几十年里一直被作为广泛研 究的对象[ 一 .近年来,SnO2在太阳能电池[ 一6】、气敏 收稿日期:2013—04—21 研究表明:SnO2主要以金红石四方相锡石结构稳定 存在,在室温条件下,四方相一氧化锡(SnO具有PbO 型结构)也是稳定存在的.四方相SnO2在光学、电学 基金项目:国家自然科学基金资助项目(11074161);上海市科委基金资助项目(10JC1405400);上海市重点学科建设资助项目(¥30109) 通信作者:陈志文(1962一),男,教授,博士生导师,博士,研究方向为纳米材料的合成与性质.E—mail:zwchen@shu.edu.cn 460 上海戈 报(自然科学版) 第l9卷 和气敏元件技术上的应用使更多的学者对其特性进行 了广泛的研究[14-22]. 具体制备过程如下:在0.2 mol/L SnCI2溶液中滴加 MnC12溶液(5 mol%,即同体积下MnC12物质的量为 SnC12的5%),充分搅拌使其混合均匀.接着将混合溶 液在130。C回流36 h,冷却后,滴加氨水使pH=5时, 反应停止.陈化24 h,过滤洗涤,将产物在真空干燥箱 中80。C干燥10 h.将烘干的产物分为若干份,分别 在250,350,450,550。C退火3 h. SnO2除了以四方相结构存在之外,还以正交相 的晶体结构a=0.471 4 nm,b=0.572 7 nill c= 0.521 4 nm)【14】存在.正交相SnO2作为一种亚稳相, 不易合成,相关的文献报道比较少.研究表明:在高 温高压的条件下,正交相SnO2才能稳定存在.Suito 等[23]在高压11.8 GPa、高温800。C条件下第一次成 功合成了正交相SnO2粉末.Lu等_24_在铁掺杂SnO2 为了对比Mn离子的作用,按照相同工艺制备 了未掺杂的SnO2,并采用日本日立公司的Rigaku— 纳米颗粒中发现了正交相SnO2.大量实验研究表明: D/MAX一2200VPC型xRD f用Cu—K 为辐射源,波 当压力释放时,反方向转化发生,转化为正交相SnO2 氟石结构.Lai等[25]首次在无挤压SnO2粉末中发现 了正交相SnO2,在惰性气体氛围和低氧压下,他们通 过蒸发凝聚方法合成超细SnO2纳米颗粒(大约6 nm). 他们还发现了另外一个现象:当样品在富氧环境下退 火时,正交相SnO2的形成会受到抑制.这是由于氧原 子通常局域在四方晶格的间隙位置 当在空气中退火 时,氧空缺浓度增加,导致晶格畸变,而有利于正交相 SnO2的形成.Kaplan等_26_则应用真空电弧沉积方法 制备了SnO2薄膜,薄膜在350 ̄500。C范围内热处理, 发现薄膜组成为正交相和四方相SnO2混合物.Kong 等I27]用金属有机气相沉积法(metal organic vapor de— position method,MOCVD)合成了正交相SnO2,这种 正交相SnO2具有OZ—PbO2型结构.本课题组运用脉 冲激光沉积(pulsed laser deposition,PLD) ̄0备了正 交相Sn02薄膜[28].实验结果表明:正交相SnO2可 以应用多种方法制备,而高温、高压或高应力可能是 正交相SnO2合成的重要因素. 本工作通过一种简单的共沉淀方法制备了Mn掺 杂Sn02颗粒,对前驱体在不同温度下热处理,并通过 x射线衍射(X—ray difraction,XRD)分析和高分辨透 射电子显微镜(high-resolution transmission electron microscopy,HRTEM)对样品的微纳米结构进行了表 征.结果表明:在不同热温度处理下,四方相和正交相 SnO2纳米晶共存于Mn掺杂的SnO2样品中.XRD 测试结果表明:随着退火温度的增加,正交相SnO2的 峰强减弱,四方相SnO2的峰强增加.HRTEM分析表 明:样品中可以同时找到四方相和正交相SnO2的晶 格条纹像,这进一步证实了正交相SnO2的存在.微 纳米结构分析证明:四方相和正交相SnO2界面晶格 错位生长和缺陷等是影响其微纳米结构特征的重要因 素.由于锰离子掺杂SnO2导致其晶格参数发生改变 而产生应力,这在正交相SnO2的形成过程中起着关 键的作用. 1 实验部分 通过化学共沉淀的方法制备了Mn掺杂Sn02. 长为0.154 178 nm,入射狭缝Ds=0.05 mm,接收狭缝 =0.15 mm.电压设置为40 kV,电流设置为40 mA, 扫描速度为8。/min,扫描范围10。^80。1和日本JEOL 公司的JSM一6700F型HRTEM对样品进行表征. 2结果与讨论 通过XRD技术测试分析不同退火温度下样品 的结晶学变化.图1分别是SnO2前驱体以及在 250,350,450,550。C退火温度下的XRD实验结 果.从XRD图谱可以看出,经过退火处理的SnO2 样品的峰强比前驱体明显增加,衍射峰变得更加尖 锐,表明退火之后样品晶化得更好.根据Scherrer’S公 式:D=KA/ ̄cos 0的分析,如图l(a1的衍射峰宽 而弱,表明前驱体SnO2颗粒的大小要小于退火处理 的样品.SnO2的主要衍射峰所对应的晶面指数分别 为(110),(101),(200),(211),(220)和(002),晶格常 数a=4.738×10_lo,C=3.187x 10_。0,其晶面指数与 JCPDS标准粉末衍射卡片(PDF文件No.41—1445) 四方相金红石型SnO2晶体结构一致. 20/( ) (a)前驱体;(b)250。c;(C)350。c;(d)450。c;(e)550。C 图1不同退火温度下SnO2颗粒的XRD图谱 Fig.1 Typical XRD patterns of pure tetragonal phase Sn02 nanoparticles after heat treatment jn air 对比图1中的(a)和(b)一(e),退火温度对Sn02 第5期 王利军,等:锰掺杂诱导正交相SnO2的生长行为 463 晶面数下降.正交相SnO2的形成是由于Mn掺杂四 方相SnO2引起的晶格畸变.本研究结果有望使SnO2 更为广泛地应用于光电子器件和气敏传感器领域. 参考文献: [1】YUSTA F J,HITCHMAN M L,SHAMLIAN S H.CVD preparation and characterization of tin dioxide films for electrochemical applications[J].J Mater Chem, 1997,7(8):1421—1427. 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