Anisotropy of the electrical conductivity of VO2 single crystals

Bongers, P. F.

doi:10.1016/0038-1098(65)90032-3

Cited by 81 publications

(33 citation statements)

References 7 publications

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“…The above value of Π IM corresponds to a rather high value of S IM ; while S M << S I , it is safe to take S IM ≈ S I . S I (340 K) of −950 µV/K is rare in the literature, but comparable values were already measured in the past [18,26,27]. Π IM (T IMT ) was measured by two methods in Reference [17]; the value found there was 0.37 V.…”

Section: Resultsmentioning

confidence: 65%

Switching VO2 Single Crystals and Related Phenomena: Sliding Domains and Crack Formation

Fisher

Patlagan

2017

Materials

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VO2 is the prototype material for insulator–metal transition (IMT). Its transition at TIMT = 340 K is fast and consists of a large resistance jump (up to approximately five orders of magnitude), a large change in its optical properties in the visible range, and symmetry change from monoclinic to tetragonal (expansion by 1% along the tetragonal c-axis and 0.5% contraction in the perpendicular direction). It is a candidate for potential applications such as smart windows, fast optoelectronic switches, and field-effect transistors. The change in optical properties at the IMT allows distinguishing between the insulating and the metallic phases in the mixed state. Static or dynamic domain patterns in the mixed-state of self-heated single crystals during electric-field induced switching are in strong contrast with the percolative nature of the mixed state in switching VO2 films. The most impressive effect—so far unique to VO2—is the sliding of narrow semiconducting domains within a metallic background in the positive sense of the electric current. Here we show images from videos obtained using optical microscopy for sliding domains along VO2 needles and confirm a relation suggested in the past for their velocity. We also show images for the disturbing damage induced by the structural changes in switching VO2 crystals obtained for only a few current–voltage cycles.

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Section: Resultsmentioning

confidence: 65%

Switching VO2 Single Crystals and Related Phenomena: Sliding Domains and Crack Formation

Fisher

Patlagan

2017

Materials

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“…1,15,16,18 However, the mechanisms of hysteresis in VO 2 are not fully understood. For bulk single crystals of VO 2 , some researchers have observed less than 1 C hysteresis width 35,36 while others have observed 6 to 25 C hysteresis width. 1,2,37 Thus, the intrinsic hysteresis of bulk VO 2 is not widely agreed upon and there is no clear baseline by which to compare nanoscale forms of the material.…”

Section: Resultsmentioning

confidence: 99%

Influence of grain size on transition temperature of thermochromic VO2

Miller

Wang

2015

Journal of Applied Physics

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A thermochromic low-emittance coating: Calculations for nanocomposites of In2O3:Sn and VO2 Appl. Phys. Lett. 99, 131907 (2011); 10.1063/1.3641869 Mg doping of thermochromic VO 2 films enhances the optical transmittance and decreases the metal-insulator transition temperature Vanadium(IV) oxide (VO 2 ) is a unique material that undergoes a reversible phase transformation around 68 C. The material could potentially be used as an energy-efficient coating for windows since its reflectance in the infrared (IR) increases significantly more than in the visible region. Currently, VO 2 is limited by a transition temperature ðs c Þ that is too high, luminous transmittance that is too low or both. In this study, a transition temperature of 45 C is achieved for a reactively sputtered, undoped film by restricting grain size to approximately 30 nm. It is concluded that a higher density of grain boundaries (smaller grain size) provides a greater number of nucleating defects which in turn reduces s c . Similarly, a higher density of grain boundaries may reduce the hysteresis width (difference between transition temperatures in heating and cooling). Also in this study, a new set of optical performance metrics is proposed in which the solar spectrum is divided into the ultraviolet (UV), visible and near infrared (NIR) regions. This approach is more closely aligned with the goals of limiting UV, allowing luminous and modulating NIR transmission. Using these metrics, the optical properties of the low-s c sample were: 2% UV transmittance, 47% luminous transmittance, and 23% NIR modulation (decrease from 43 to 33%). This study demonstrates that the grain size of VO 2 should be viewed as an important parameter for controlling the transition temperature of the material. V C 2015 AIP Publishing LLC. [http://dx.

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“…Their electronic and lattice properties also show distinct temperature dependences and anisotropic behaviors [20,26,[33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

et al. 2015

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We have systematically studied a variety of vanadium dioxide (VO 2 ) crystalline forms, including bulk single crystals and oriented thin films, using infrared (IR) near-field spectroscopic imaging techniques. By measuring the IR spectroscopic responses of electrons and phonons in VO 2 with sub-grain-size spatial resolution (~20 nm), we show that epitaxial strain in VO 2 thin films not only triggers spontaneous local phase separations but also leads to intermediate electronic and lattice states that are intrinsically different from those found in bulk. Generalized rules of strain and symmetry dependent mesoscopic phase inhomogeneity are also discussed. These results set the stage for a comprehensive understanding of complex energy landscapes that may not be readily determined by macroscopic approaches.

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Anisotropy of the electrical conductivity of VO2 single crystals

Cited by 81 publications

References 7 publications

Switching VO2 Single Crystals and Related Phenomena: Sliding Domains and Crack Formation

Switching VO2 Single Crystals and Related Phenomena: Sliding Domains and Crack Formation

Influence of grain size on transition temperature of thermochromic VO2

Phase transition in bulk single crystals and thin films ofVO2by nanoscale infrared spectroscopy and imaging

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