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Toward reproducible metal-insulator transition characteristics in V <sub/>2</sub> O <sub/>3</sub> thin films sputter-deposited on glass
摘要： Vanadium sesquioxide (V2O3) exhibits remarkable property changes through its metal-insulator transition near 150 K and is a very promising candidate for device applications. Thin V2O3 films were deposited on SiO2 glass by reactive DC magnetron sputtering. While resistivity changes over four orders of magnitude were demonstrated, films deposited under nominally identical conditions exhibited significant differences in electrical characteristics, which would hinder reproducibility under deposition techniques appropriate for industrial scale production with standard control features. These differences were attributed to small deviations from exact stoichiometry. A post-deposition thermal treatment consistent with equilibrium temperature and oxygen pressure conditions for V2O3 applied to the samples succeeded in nearly equalizing their characteristics within a relatively short time and without negatively impacting the glass substrate or film continuity. Analysis of film structure, morphology, and resistivity measured from room temperature through the metal-insulator transitions, both before and after the thermal process, revealed information about the interplay between non-stoichiometry, residual stress, and electrical characteristics of the films. The approach employed can lead to reproducible results for V2O3 films and is applicable to similar materials which exhibit metal-insulator transitions.
关键词： stoichiometry,sputtering,thin films,V2O3,thermal treatment,metal-insulator transition
更新于2025-09-09 09:28:46
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Metal-Organic Framework Derived Hierarchical Co/C@V2O3 Hollow Spheres as a Thin, Lightweight and High-Efficiency Electromagnetic Wave Absorber
摘要： Developing high-efficiency electromagnetic (EM) wave absorbing materials with light weight, thin thickness and wide absorption bandwidth is highly desirable for ever-developing electronic and telecommunication devices. Herein, hierarchical metal-organic framework (MOF)-derived Co/C@V2O3 hollow spheres were designed and synthesized through a facile hydrothermal, precipitation and pyrolysis method. The composite exhibits both excellent impedance matching and light weight due to the rational combination of hollow V2O3 spheres and porous Co/C. Additionally, multiple components enable a large dielectric and magnetic loss of the composite, giving rise to enhanced EM wave absorption performance with a maximum reflection loss (RL) of -40.1 dB and a broad effective absorption bandwidth (RL < -10 dB) of 4.64 GHz at a small thickness of 1.5 mm. This work provides insights into the design of hierarchical hollow and porous composites as a thin and lightweight EM wave absorbers with efficient absorption, which can also be extended to energy storage, catalysis and sensing.
关键词： Co/C@V2O3 composites,metal-organic framework,hierarchical hollow spheres,dielectric/magnetic composites,electromagnetic wave absorption
更新于2025-09-09 09:28:46
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Metal-insulator transition in V <sub/>2</sub> O <sub/>3</sub> thin film caused by tip-induced strain
摘要： We have demonstrated pressure-induced transition in a c-axis oriented vanadium sesquioxide (V2O3) thin film from a strongly correlated metal to a Mott insulator in a submicrometric region by inducing a local stress using contact atomic force microscopy. To have an access to a pressure range of sub-gigapascal, a tip with a large radius of 335 nm was prepared by chemical vapour deposition of platinum onto a commercial tip with a focused ion beam (FIB). The FIB-modified tip gives a good electrical contact at low working pressures (0.25–0.4 GPa) allowing unambiguously to evidence reversible metal-insulator transition in a pulsed laser-deposited V2O3 thin film by means of local investigations of current-voltage characteristics. A finite element method has confirmed that the diminution of the c/a ratio under this tip pressure explains the observed phase transition of the electron density of states in the film.
关键词： tip-induced strain,Mott insulator,metal-insulator transition,V2O3 thin film,atomic force microscopy
更新于2025-09-09 09:28:46