Hydrothermal Synthesis Of La And Nd Doped WO₃ Powders And Studies On Their Photochromic Properties

The photochromic materials have potential applications in various fields,such as display,storage,signal processing and so on.WO₃ is a typical inorganic transition metal oxides and extensively studied as photo and electric functional materials.The WO3 powders also have photochromic properties,but it requires special light source to be activated and the current materials is poor in photochromic property.In this paper,WO₃ powders doped with different concentrations for rare earth elements were prepared by low temperature hydrothermal method,using sodium tungstate,neodymium nitrate,lanthanum nitrate and hydrochloric acid as raw materials.The microstructure and morphology were investigated by X-ray diffraction?XRD?,)scanning electron microscopy?SEM?and X-ray photoelectron spectroscopy?XPS?.The photochromic properties of WO₃ powders were tested by using UV-Vis and automatic chromatic aberration instruments.The results are as following:1.The WO₃ powders synthesized without reaction aids are monoclinic phase,have no photochromic properties due to the lack of special pore structure.2.The Nd-doped WO3 powders with special structure were successfully synthesized.The Nd³⁺was successfully doped into the WO₃ lattice,and the W⁶⁺was reduced to W⁵⁺,which made the WO₃ powders changed from yellow light to blue one under ultraviolet lamp irradiation.Moreover,the WO₃ powders doped with 10%Nd element exhibit the best photochromic properties.3.The La-doped WO₃ powders with special structure were also successfully synthesized.It was proved that La³⁺was successfully doped into the WO₃ lattice,so that the W⁶⁺was reduced to W⁵⁺,and the WO₃ powders changed from yellow light to blue one under UV light irradiation.Meanwhile,the WO₃ powders doped with 10%La element show the best photochromic properties.4.The experimental results show that the doping effect of Nd is better than that of La.