氧化锌叶片状纳米晶的结构和光谱特性

熔盐法对sol-gel法生成的前驱物处理合成新颖的叶片状的氧化锌纳米结构,TEM照片显示其长度300-500nm,宽度为50-80nm,两头尖端约呈25°夹角,形状基本沿中轴呈中心对称。其生长过程进行了研究:弯曲了的ZnO纳米棒闭合形成框架结构,框架内沿中轴方向并排生长的ZnO纳米线填满框架内的空隙形成叶片状的氧化锌纳米结构。Raman谱测量发现该结构是晶化的六角相氧化锌。对叶片状的氧化锌的声子限制效应进行了研究,并与纳米颗粒氧化锌予以比较。435cm-1的E2峰的Fano不对称具有正的Fano耦合系数。发现在585nm处出现光致发光峰,归于ZnO纳米结构中氧缺陷的作用。

Structural and Spectroscopic Characters of Leaf-shaped ZnO Nanocrystals

A novel leaf shape-structured ZnO nanocrystal(LSSZN)was synthesised by molten-salt method growth from the precursor produced by sol-gel method.TEM image shows that LSSZN is symmetric along central long axis with length of 300-500 nm,width of 50 to 80 nm,and the end angle of about 25°.The formation process of the leaf shape-structure is described as follows.Two ZnO nanorods bend to each other to form the leaf-shaped frame.Many nanowires grow along the long axis within the frame,and finally fill the whole frame in parallel arrangement to form the leaf shape-structured ZnO nanocrystal.Raman spectroscopy indicates the leaf-shaped nanocrystal has hexagonal phase structure.Lineshapes of the 435cm-1 E_2 modes for both LSSZN and ZnO nanocrystal were found to have Fano asymmetry.However,the former peak is sharply cutoff on the low-energy side,showing negative Fano coupling coefficient;while the latter is sharply cut-off on the high-energy,showing positive Fano coupling coefficient.Photoluminance spectrum reveals a peak centered at 585 nm.The origin of the emission is attributed to oxygen vacancies in LSSZN.