Room temperature tunability of Mo-doped VO 2 nanofilms across semiconductor to metal phase transition

Khan, Gulzar; Asokan, K.; Ahmad, Bilal

doi:10.1016/j.tsf.2017.02.006

Cited by 42 publications

(23 citation statements)

References 43 publications

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“…Doped VO 2 films with 0, 1, 3 and 5% of Mo 6+ -ions were synthesised by the same process with the addition of an appropriate amount of MoO 3 (Sigma Aldrich) and melted in a ceramic crucible at 800-900°C for 25-30 min in a muffle furnace in an ambient atmosphere. The molten liquid was immediately transferred into distilled water at 80°C with constant stirring for 3-5 h and then the solution was homogenised in an ultrasonic bath for >1 h. Subsequent to the ageing of 24 h, the V 2 O 5 gel was spin-coated on each cleaned alumina substrate at a spin rate of 3000 rpm for 30 s by three successive coatings [3]. Thin films of VO 2 for irradiation were similarly fabricated by melting 3.7 g of V 2 O 5 (Sigma Aldrich, purity 99.9%) and 5.40 g of H 2 C 2 O 4 •2H 2 O (Sigma Aldrich) in a ceramic crucible at 750°C in a muffle furnace for 30 min and then poured quickly into a beaker containing 30 ml of deionised water placed on a magnetic stirrer.…”

Section: Film Fabricationmentioning

confidence: 99%

“…Vanadium dioxide (VO 2 ), a strong electron correlated metal oxide, has been the focus of extensive research because it undergoes first-order thermal reversible structural phase transition between high stable, less symmetric (P21/c), low temperature monoclinic (M1) semiconducting phase and low stable, high symmetric (P42/mnm), high-temperature tetragonal rutile (R) metallic phase (SMT) [1]. This SMT of VO 2 is scientifically exciting and technologically appealing around a phase transition temperature (T t ) of 341 K closest to room temperature than any other material discovered to date in its un-irradiated, un-doped, and bulk state [2][3][4][5].…”

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confidence: 99%

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Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO ₂ thin films

Khan

2020

Micro & Nano Letters

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The origin of the structural phase transition in vanadium dioxide (VO 2) has been the subject of immense disagreement in spite of decades of research carried out to comprehend this intriguing phenomenon. Diverse models have been developed to elucidate the obscure theory in order to corroborate assorted experimental results. Herein, the influence of swift heavy ion irradiation, elemental doping and coating cycles on the structural properties of thin films synthesised by sol-gel technique and deposited by spin coater on alumina and glass substrates is investigated. The thin films were characterised by X-ray diffractometry and the XRD spectra obtained at 1E11, 5E11, 1E12 ion beam fluances of 200 MeV Ag 9+-ion irradiation; at 1, 3, 5% of Mo 6+-ion doping and at different spin coating cycles were analysed to probe the influence of these effects on the structural characteristic parameters of nanocrystallites in VO 2 thin films. This aspect of VO 2 thin films has not been investigated to its full capacity and consequently, not reported in the scientific literature.

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Section: Film Fabricationmentioning

confidence: 99%

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confidence: 99%

Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO ₂ thin films

Khan

2020

Micro & Nano Letters

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“…Doping is considered to the most effective strategy to reduce the ζ c of VO 2 , especially for high-valence ions doping (such as Nb 5+ , Mo 6+ , W 6+ , Tb 3+ , etc.) [21][22][23][24]. Chae et al [25] reported that the doped VO 2 with W and Ti using the sol-gel method led to a change of transition temperature and reduces the properties of MIT.…”

Section: Introductionmentioning

confidence: 99%

A Novel Method for Notable Reducing Phase Transition Temperature of VO2 Films for Smart Energy Efficient Windows

et al. 2019

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Although Vanadium dioxide (VO2) has a potential application value for smart energy efficient windows because of its unique phase transition characteristic, there are still many obstacles that need to be overcome. One challenge is to reduce its high transition temperature (ζc = 68 °C) to near room temperature without causing its phase transition performance degradation. In this paper, a novel method was employed that covered a 3 nm ultra-thin heavy Cr-doped VO2 layer on the pure VO2 films. Compared with the as-grown pure VO2, obviously, phase transition temperature decreasing from 59.5 °C to 48.0 °C was observed. Different from previous doping techniques, almost no phase transition performance weakening occurred. Based on the microstructure and electrical parameters measurement results, the mechanism of ζc reducing was discussed. The upper ultra-thin heavy Cr-doped layer may act as the induced role of phase transition. With temperature increasing, carrier concentration increased from the upper heavy Cr-doped layer to the bottom pure VO2 layer by diffusion, and induced the carrier concentration reach to phase transition critical value from top to bottom gradually. The present method is not only a simpler technique, but also avoids expensive alloy targets.

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“…Ion doping process have been developed to try and address this issue. Doping mainly divided into two types: The first type involves the use of high valence state cations such as W 6+ , Mo 5+ , Nb 5+ , which are known to decrease the phase transition temperature by introducing extra electrons into the VO 2 sample [18,19,20]; The second type is to utilizes low valence state cations, such as Al 3+ , Cr 3+ , to increase the phase transition temperature of the VO 2 derived materials [21,22,23]. However, there is no clear explanation currently existing to clarify the beneficial effects of substitution V 4+ ions with Ti 4+ ions or Zr 4+ ions that have the same valence state.…”

Section: Introductionmentioning

confidence: 99%

Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO2 Powder

Wang

et al. 2019

Nanomaterials

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In this work, V1−xZrxO2 powder (x = 0, 0.01, 0.02, 0.04) was synthesized by two step hydrothermal method. The micro-topography, magnetic and phase transition properties have been investigated using various measurement techniques. All prepared V1−xZrxO2 powder samples exhibit monoclinic structure at room temperature. With the Zr4+ ions doping concentration increased, the shapes of VO2 particles change from spherical to rectangular slice. Besides, the saturation magnetic moment of the samples decrease with the increase of doped Zr4+ ions concentration, while their phase transition temperature increase gradually with Zr ions doping at a rate of around 2 °C/at% on average. We investigated the Zr doping effects on V-V dimers and confirmed the role of V-V dimers in phase transition. We speculate that more V-V dimers form with Zr doping by magnetic measurements, which result in the monoclinic phase of Zr-doped VO2 sample is more stable than rutile phase. Therefore the phase transition temperature is elevated by Zr doping in our experiment. We further consider that the VO2 phase transition should be ascribed to Peierls transition caused by the changing of V-V dimers.

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Room temperature tunability of Mo-doped VO 2 nanofilms across semiconductor to metal phase transition

Cited by 42 publications

References 43 publications

Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO ₂ thin films

Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO ₂ thin films

A Novel Method for Notable Reducing Phase Transition Temperature of VO2 Films for Smart Energy Efficient Windows

Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO2 Powder

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Room temperature tunability of Mo-doped VO 2 nanofilms across semiconductor to metal phase transition

Cited by 42 publications

References 43 publications

Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO 2 thin films

Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO 2 thin films

A Novel Method for Notable Reducing Phase Transition Temperature of VO2 Films for Smart Energy Efficient Windows

Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO2 Powder

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Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO ₂ thin films

Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO ₂ thin films