Preparation And Properties Of Vanadium Pentoxide Thin Films Doped With Rare Earth

V₂O₅is the most stable oxide in vanadium oxygen system.As a powder material or thin film material,it has a wide range of application potential in many scientific fields,which is mainly attributed to its special layered structure,high energy density,good chemical and thermal stability,and excellent optical and electrical properties.In this paper,V₂O₅films were deposited on FTO conductive glass substrate by electrodeposition assisted sol-gel process,and doped with Ce and Y elements.The effects of precursor concentration,deposition voltage,deposition time and element doping on the structure,morphology and optical properties of V₂O₅films were analyzed.The specific research content and results are as follows:（1）Highly crystalline V₂O₅films were deposited on FTO conductive glass substrates by electrodeposit-assisted sol-gel technique.The crystal structures of undoped films and the Ce,Y element doped V₂O₅thin films were determined by X-ray diffractometer.The results show that all films are V₂O₅crystals with layered structure.As the amount of Ce and Y doping is increased,the diffraction peak shifts to a small angle,indicating that Ce and Y elements enter the V₂O₅lattice.The SEM test shows that the surface of the films were evenly distributed in granular shape.（2）The doping forms of doped elements were analyzed by X-ray photoelectron spectroscopy and Raman spectroscopy.The results show that Ce element mainly enters the V₂O₅lattice in the form of+3 valence,and the Raman peak strength of V₂O₅film decreases with the increase of Ce element.Y element also enters the V₂O₅lattice in the form of+3 valence.With the increase of Y element doping amount,the Raman peak strength of V₂O₅film gradually increased.The change of the Raman peak strength is mainly caused by the change of the content of vibratory groups in the sample.The doping of both Ce and Y elements caused the characteristic Raman peaks of V₂O₅thin films slightly redshifted.（3）The effects of precursor concentration,deposition voltage,deposition time and element doping on the optical properties of V₂O₅thin films were analyzed by ultraviolet-visible spectrophotometer.The results show that V₂O₅films prepared under the conditions of 1:100 precursor concentration,1 V deposition voltage and 60 min deposition time have the best transmittance.After the addition of Ce and Y elements,the transmittance of V₂O₅film decreases,the optical band gap becomes narrower,and the absorption edge moves to the direction of long wave,resulting in red shift.（4）The effects of doping on the infrared transmittance of V₂O₅films were investigated using Fourier infrared spectroscopy.The results show that the doping of Ce and Y elements both enhances the infrared reflectance of V₂O₅films.The infrared transmittance changes of V₂O₅films,Ce doped V₂O₅films and Y doped V₂O₅films before and after the phase transition are 69%,53.9%and 59.9%,respectively,showing excellent optical properties.（5）The effects of different doping concentrations on the mechanical properties of V₂O₅thin films were investigated by nanoindentation technique.The results show that the doping of Ce and Y elements can enhance the mechanical properties of V₂O₅films,and the hardness and elastic modulus of the doped films are higher than those of the pure V₂O₅films.When the doping amount of Ce is 1.0 at%,the mechanical properties are the best,and the hardness and elastic modulus are 8.66 GPa and 91.80 GPa,respectively.The best mechanical properties were achieved at 0.5 at%of element Y,with hardness and modulus of elasticity of 5.48 GPa and 81.52 GPa,respectively.