Ag@TiO_2核壳纳米粒子的制备与红外发射率研究

在TX-100/环己烷/正己醇/水组成的油包水（W/O）体系中,采用微乳液法制得Ag@TiO2核壳纳米粒子.采用透射电镜（TEM）,X线衍射（XRD）,红外光谱（IR）和紫外可见光谱（UV-Vis）等对其形貌和物相进行分析.利用IR-1红外发射率测量仪测定复合粒子在8～14μm波段的红外发射率.结果表明：该核壳纳米粒子粒径约50 nm,内核为面心立方的金属Ag,外壳为无定型的TiO2.被TiO2包覆后Ag核的紫外共振吸收峰与纯胶体Ag相比发生了微弱红移.高反射性能的金属Ag的引入使该核壳结构复合物的红外发射率明显降低,最低可降至0.483.Ag@TiO2核壳纳米粒子的红外发射率随着外层TiO2结晶性能的提高而下降.

Study on the Preparation and Infrared Emissivity of Ag@TiO_2 Core-shell Nanoparticles

Ag@TiO2 core-shell nanoparticles are obtained in the water-in-oil（W/O） emulsions which are composed of TX-100,cyclohexane,hexanol and water.Transmission electron microscopy（TEM）,X-ray diffraction（XRD）,infrared spectrometer（IR） and ultraviolet visible spectrum（UV-Vis） are used to analyze the morphology and composition of the samples.The infrared emissivity values during 8-14 μm wave band of the particles are measured by IR-1 infrared radiometer.The results show that the diameter of the sample is approximately 50 nm.In addition,the core-shell structure was composed of a crystalline silver core and amorphous TiO2 shells.UV-Vis spectra indicate that the plasma resonance absorption peak of silver core wrapped with TiO2 had a red shift.The Ag@TiO2 core-shell nanoparticles have lower infrared emissivity values than single inorganic materials of titania,with the lowest value down to 0.483.Moreover,the better the crystalline of the outer layer,the lower the infrared emissivity value of the composites is.The high reflectivity of metal Ag leads to the decrease in infrared emissivity value of the nanocomposites.