SnO$lt;sub$gt;2$lt;/sub$gt;纳米晶体的制备、结构与发光性质

使用软化学方法在碱性溶液中制备出了颗粒尺寸分布均匀的SnO₂纳米颗粒，使用透射电子显微镜（TEM）、X射线衍射（XRD）、光致发光谱（PL）和光吸收谱等方法分析与表征了SnO₂纳米颗粒的结构和光学性能.实验中通过表面活性剂的加入来控制纳米颗粒的结晶与凝聚.XRD，TEM的结果表明，原始制备出的SnO₂纳米颗粒的平均粒径小于4 nm，为完好的晶体状态.纳米颗粒经过400—1000 ℃退火后晶粒尺寸进一步增大.光吸收谱表明，相对于体材料，纳米颗粒的禁带宽度展宽并随颗粒尺寸增大而红移.光致发光谱测试表明，不同温度下退火的SnO₂纳米颗粒在350—750 nm有较强的发光，研究表明这是来源于颗粒表面的氧空位缺陷发光. 关键词： 氧化锡 表面活性剂 纳米颗粒 光致发光

Synthesis，structures and luminescence properties of SnO2 nanoparticles

As a wide band-gap semiconductor，SnO₂ films have attracted much attention due to their novel optical and electronic properties. It has been reported that the physical properties can be quite different when the size of SnO₂ is reduced to nanometer scale due to the large surface-to-volume ratio and the quantum size effects，which may be applied in many kinds of devices, such as solar cells sensors. etc. It is interesting to study the synthesis of SnO₂ nanoparticles and their physics properties. In the present work，a soft chemical technique was used to prepare SnO₂ nanoparticles with uniform size and good crystallization in alkalescent solution. The surfactant was added during the preparation process to control the growth and agglomeration of crystal precipitates in the solution. X-ray diffraction spectra and transmission electron microscopy were used to characterize the structures of SnO₂ nanoparticles before and after thermal annealing. It was found that the nanocrystalline SnO₂ particles can be formed by the present technique and the size is about 4 nm with good crystallinity. With changing the preparation parameters，the size of nanocrystalline SnO₂ particles is changed. Post thermal annealing at various temperatures （400—1000 ℃） can promote the crystallization and the size of formed particles was increased with increasing annealing temperature. Optical absorption spectra were used to see the change of the optical properties for samples prepared under different conditions. It was found that the optical band gap is enlarged in nanocrystalline SnO₂ particles compared with its bulk counterpart, which can be attributed to the quantum confinement effect. The red-shift of the optical band gap with the particle size supported the quantum size effect. A broad photoluminescence band in the range of 350—750 nm can be detected in the annealed samples and the intensity was significantly enhanced after the thermal annealing. The luminescence peak energy was kept at 390 nm which was independent of the particle size. This luminescence band can be ascribed to the luminescence center associated with the oxygen vacancies on the SnO₂ particle surface.