Effect Of Gadolinium,zirconium,and Neodymium Doping On The Structure And Phase Transformation Characteristics Of Vanadium Dioxide

Vanadium dioxide?VO₂?has significant and reversible metal-insulator phase transition characteristics around 68°C.This phase transition can make the optical,electrical and magnetic properties of vanadium dioxide abrupt.More importantly,its crystal structure can be changed by doping,which effectively reduces the phase transition temperature and makes it closer to room temperature.This has laid a solid foundation for the application of VO₂ in new fields such as smart materials and energy-saving materials.In this paper,V₂O₅?99.9%?is used as the raw material,oxalic acid?H₂C₂O₄?is the reducing agent,and urea?CH₄N₂O?is the precipitating agent.M-phase VO₂ powder is prepared by hydrothermal synthesis.Using Gd?NO₃?₃,Zr?NO₃?₄ and Nd?NO₃?₃ as dopants,the effects of Gd,Zr,Nd and other elements on the structure and phase change performance of VO₂?M?powder were studied.Use X-ray diffractometer?XRD?,scanning electron microscope?SEM?,nanometer particle size analyzer,Fourier infrared spectrometer?FTIR?and X-ray photoelectron spectrometer?XPS?Scientific characterization and analysis of morphology,particle size,phase transition temperature and infrared transmittance.?1?XRD analysis results show that the hydrothermal method combined with high temperature heat treatment can produce VO₂?M?with good phase.The phase of the doped powder is mainly VO₂?M?phase,and the peak shape is sharp.,The intensity is higher,and the compliance with the VO₂ standard PDF card is higher,indicating that the VO₂?M?crystallinity is better.XPS analysis results show that there are characteristic peaks corresponding to the doped elements in the doped VO₂?M?photoelectron spectrum.Compared with the standard binding energy,it is found that the peak shape peak position is highly matched.The presence of doped elements Gd,Zr,and Nd in the vanadium dioxide samples are+3,+4,and+3,which is consistent with the XRD analysis results,indicating that Gd,Zr,and Nd were successfully incorporated into the VO₂?M?crystal Grid.?2?The results of SEM analysis show that the morphology of vanadium dioxide after doping has changed significantly.Pure VO₂?M?powder particles have a neatly distributed spherical-like morphology with a large particle size,but after doping The particle size of VO₂?M?is reduced by more than 50%,the particles are spherical and there is a certain phenomenon of particle agglomeration.The EDS spectrum shows that the powder contains only V,O and doping elements,and no other impurity elements are found,indicating that the sample has high purity.?3?Differential scanning calorimetry test results show that when doped with 2%,4%,and 6%Gd,respectively,the phase transition temperature of VO₂?M?can be reduced to65.9?,64.6?,60.3?;when doped At 2%,4%and 6%Zr,the phase transition temperature of VO₂?M?can be reduced to 66.8?,65.4?,61.1?;when doped with 9%Nd,the phase transition temperature of VO₂?M?can be reduced to 63.5?,58.8?,55.6?.It can be seen that the phase change temperature of VO₂ caused by doping different elements is different,and the phase change temperature of vanadium dioxide doped with Nd element is the most significant.At the same time,under different doping concentrations of the same element,its phase transition temperature decreases with increasing doping concentration.?4?Fourier infrared transmittance test results show that when the temperature is close to the VO₂?M?powder phase transition point,the powder undergoes a reversible metal-insulating phase transition,and the infrared transmittance of the powder after the phase transition Significantly reduced,the change is most obvious when doped with Nd element,VO₂?M?after phase transition has obvious characteristic peaks at 700cm^-1 and 3453cm^-1,infrared light transmittance can be as low as 4%,which will have It is beneficial for vanadium dioxide to be better applied in the field of intelligent and energy-saving materials.