热处理气氛对Co掺杂SnO_2纳米颗粒微结构及光致发光性能的影响

Annealing Atmospheres Effects on the Microstructure and Photoluminescence of Co-doped SnO_2 Nanoparticles

采用共沉淀法制备了Co掺杂SnO2纳米颗粒,并分别在氧气,氮气,真空环境下进行500℃热处理,研究热处理气氛对样品微观结构及光致发光特性的影响。纳米颗粒为单晶金红石型SnO2相,热处理不改变相结构,且没有Co金属析出和氮化物形成。X射线吸收近边谱结果说明经真空和氮气热处理的SnO2纳米颗粒存在大量氧空位,氧气热处理后本征氧空位数量大幅减少。纳米颗粒在3种气氛热处理后均观察到了蓝光和橘红光发光带,且氧气热处理的样品橘红光强度较氮气和真空热处理有大幅下降。结合微观结构分析,橘红发光带是由于氧空位捕获电子形成离子化空穴,在SnO2能隙中构成新的施主能级引起的。氮气热处理后,N2p轨道与O2p轨道杂化,使发光峰向长波方向漂移。

Co-doped SnO2 nanoparticles have been prepared by co-precipitation method. The thermal annealing of the nanoparticles was carried out in different atmospheres at 500 oC. The effects of annealing atmospheres on the microstructure and photoluminescence properties were investigated. Structural analyses reveal that all the samples consist of pure rutile tetragonal phase which would not change after annealing. The quality of nanoparticles is improved by thermal annealing. During the N2 annealing, N ions incorporate the SnO2 lattice to substitute the Sn4+ site and form O-Sn-N bonding. The concentration of oxygen vacancies would be enhanced under N2 and vacuum annealing and passivated under O2 annealing. The orange band emission abruptly decrease its intensity after annealing in O2.