二氧化钒(VO₂)是电子强关联体系的典型代表, 其晶体结构在特定阈值的温度、电场、光照和压力等物理场作用下会发生由单斜金红石结构向四方金红石结构的可逆转变, 从而引发绝缘-金属相变. 其中, 电场诱导VO₂绝缘-金属相变后的电导率可提高2－5个数量级, 在可重构缝隙天线、太赫兹辐射以及智能电磁防护材料等领域具有广阔的应用前景, 成为近年来人们的研究热点.首先, 简要概述了VO₂发生绝缘-金属相变时晶体结构和能带结构的变化, 进而从电场诱导VO₂绝缘-金属相变的研究方法、响应时间、临界阈值场强调控以及相变机理几个方面系统总结和评述了近年来国内外学者在该领域的重要发现和研究进展.最后, 指出了当前VO₂绝缘-金属相变研究存在的问题, 并展望了未来的发展方向.

Epoxy resin (ER)/micron-aluminum particles (MP) composites with different filling concentration of spherical particles were fabricated. The nonlinear conductive behavior of ER/MP composites under increasing applied voltage using the improved V-I method was investigated. Under sufficient high intensity applied constant voltage, the obvious conductive switching behavior of samples with volume fraction 12.7%, 16.9% and 18.9% was found. The conductivity of ER/MP composites increase up to 3–4 orders of magnitude when the conductor-insulator transition occurs. The switching threshold voltage decreases with the increase of volume fraction of MP in the composites. The results show that the ER/MP composites with conductive switching properties are of great potential application in electromagnetic protection of electron devices and systems.

Vanadium dioxide is a typical representative of a strong electronic correlation system. Triggered by stimuli such as heat and electric fields, VO₂ can undergo a reversible transition from insulating to metallic phase and has therefore attracted attention of many researchers. In this work, a hydrothermal method was used to prepare nano-VO₂ particles with phase transition. According to the phenomenology, finite element simulation and theoretical calculation models of the electro-induced phase transition (E-MIT) in the VO₂-filled Polyethylene glycol were established. Electrode-gap effect on the phase-transition voltage of E-MIT was discussed. Furthermore, the phase transition and heat distribution processes were analyzed. The results revealed that high-temperature conductive channels are formed in the VO₂ structure during the electro-induced phase transition. Moreover, position of these channels is determined by the high-voltage edge effect of the electrode and the heat dissipation effect of the material. The ideal adiabatic E-MIT process was also evaluated. The phase change voltage curve of the theoretical model was well matched with the simulation model. The results reveal that the temperature in the channel is significantly lower than the typical phase change temperature when a phase transition occurs. In addition, owing to an applied voltage, the resistance of the VO₂ composite material can drop suddenly even if the temperature rise is small. The analysis results verified that Joule heating is an important factor in the electro-induced phase transition of VO₂-filled polymers. The experimental results are helpful in understanding the E-MIT mechanism of VO₂ composite materials and the subsequent application of these materials.