Controlling the electronic structure of SnO2 nanowires by Mo-doping

Mo-doped SnO2 (MTO) nanowires are synthesized by an in-situ doping chemical vapour deposition method. Raman scattering spectra indicate that the lattice symmetry of MTO nanowires lowers with the increase of Mo doping, which implies that Mo ions do enter into the lattice of SnO2 nanowire. Ultraviolet-visible diffuse reflectance spectra show that the band gap of MTO nanowires decreases with the increase of Mo concentration. The photoluminescence emission of SnO2 nanowires around 580 nm at room temperature can also be controlled accurately by Mo-doping, and it is extremely sensitive to Mo ions and will disappear when the atomic ratio reaches 0.46%.     

Hydrothermal synthesis and chromic properties of hexagonal WO3 nanowires

This paper reports that highly purified hexagonal WO 3 nanowires are synthesized by a simple hydrothermal method.The as-synthesized WO 3 nanowires are investigated in detail by ultraviolet-visible-near infrared spectroscopy and electrical transport measurements under different conditions.It finds that the optical band gap and the diffuse reflection coefficient in the wavelength region above 450 nm of WO 3 nanowires decrease observably upon exposure to ultraviolet light or NH 3 gas.It is also found that there are electrons being trapped or released in individual WO 3 nanowires when scanning bias voltage in different directions upon exposure to ultraviolet and NH 3 gas.The experimental results suggest that the chromic properties might be attributed to the injection/extraction of hydrogen ions induced by ultraviolet light irradiation in air or creation/annihilation of oxygen vacancies induced by NH 3 gas exposure,which serve as colour centres and trap electrons as polarons.The experimental results also suggest that the hexagonal WO 3 nanowires will be a good candidate for sensing reduced gas such as NH 3.     

化学气相沉积法制备Sn2S3一维纳米结构阵列

运用化学气相沉积法(CVD), 直接以Sn和S为原料分区加热蒸发, 通过控制温度分布、气压、载气流量和金属铅纳米颗粒分布等宏观实验条件, 成功制备大面积Sn₂S₃一维纳米结构阵列. 扫描电子显微镜(SEM)图片显示: Sn₂S₃一维纳米结构的横向尺度在100 nm左右, 长约几个微米. X射线衍射（XRD）谱显示: 所制备样品的晶体结构属于正交晶系, 沿[002]方向生长. 紫外-可见漫反射谱表明Sn₂S₃一维纳米结构是带隙为2.0 eV的直接带隙半导体. 讨论了温度分布和金属铅纳米颗粒对Sn₂S₃一维纳米结构生长的影响, 并指出其生长可能遵循气-固(V-S)生长机理.