The Structural Phase Transition in Individual Vanadium Dioxide Nanoparticles

2009 ◽  
Vol 1184 ◽  
Author(s):  
Felipe Rivera ◽  
Robert C. Davis ◽  
Richard Vanfleet
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Vanadium Dioxide ◽  
Structural Phase ◽  
Polycrystalline Thin Films ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
Insulator Phase Transition ◽  
Means Of Transmission ◽  
Individual Particles

AbstractVanadium dioxide (VO2) single crystals undergo a structural first-order metal to insulator phase transition at approximately 68°C. This phase transition exhibits a resistivity change of up to 5 orders of magnitude in bulk specimens. We observe a 2-3 order of magnitude change in thin films of VO2. Individual particles with sizes ranging from 50 to 250 nm were studied by means of Transmission Electron Microscopy (TEM). The structural transition for individual particles was observed as a function of temperature. Furthermore, the interface between grains was also studied. We present our current progress in understanding this phase transition for polycrystalline thin films of VO2 from the view of individual particles.

Structural Phase Transition of Tungsten-Doped Vanadium Dioxide Nanopowders Prepared by Thermolysis

2008 ◽  
Vol 8 (3) ◽  
pp. 1417-1421 ◽  
Author(s):  
Zifei Peng ◽  
Wei Jiang ◽  
Heng Liu
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Vanadium Dioxide ◽  
Structural Phase ◽  
Hysteresis Loops ◽  
Tungstic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron

Tungsten-doped vanadium dioxide (VO2) nanopowders were prepared by thermolysis of (NH4)5[(VO)6(CO3)4(OH)9] · 10H2O at low temperature, with active white powdery tungstic acid used as a substitutional dopant. The composition and microstructure of the powders were examined by X-ray diffraction, transmission electron microscope, and differential scanning calorimetry. The change in electrical resistance due to the S–M transition was measured from 0 to 150 °C by the four-probe method. Hysteresis loops and differential scanning calorimetry analysis of the samples indicated that the phase-transition temperature of VO2 nanopowders was 67.15 °C. For tungstendoped VO2 nanopowders, the temperature was reduced to 26.46 °C. After sintering the nanopowders, Tc rose from 26.46 °C to 34.85 °C with the sizes increasing to the bulk. A significant direct correlation between particle size and Tc was confirmed. The results indicated that white powdery tungstic acid is exceptionally effective as a dopant for reducing transition temperature.

Effect of grain sizes on the metal-semiconductor phase transition in vanadium dioxide polycrystalline thin films

2006 ◽  
Vol 48 (5) ◽  
pp. 929-934 ◽  
Author(s):  
R. A. Aliev ◽  
V. N. Andreev ◽  
V. M. Kapralova ◽  
V. A. Klimov ◽  
A. I. Sobolev ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Vanadium Dioxide ◽  
Grain Sizes ◽  
Polycrystalline Thin Films

Characterization of phase-transition-induced micro-domain structures in vanadium dioxide

2014 ◽  
Vol 47 (2) ◽  
pp. 732-738
Author(s):  
Ping Lu ◽  
Jiadong Zhou ◽  
Xinling Liu ◽  
Zongtao Zhang ◽  
Fangfang Xu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Vanadium Dioxide ◽  
Structural Phase ◽  
Group Method ◽  
M1 Phase ◽  
Domain Structures ◽  
Transmission Electron ◽  
First Order Transition ◽  
Antiphase Domains

The displacive structural phase transition of vanadium dioxide (VO2) from the high-temperature tetragonal rutile (R) phase to the low-temperature monoclinic M1 or M2 phase may induce the formation of a variety of domain structures. Here, all possible types of phase-transition-induced domain structures of the M1 and M2 phases have been theoretically formulated by using a general space group method. The predicted domain structures of the M1 phase, including mirror or rotation twins and antiphase domains, have been confirmed by transmission electron microscopy observation of VO2powders and films, while the antiphase domains have never been involved in previous studies. The changes undergone by domain structures during a thermal or electron-beam-induced phase transition have been investigated. These results may suggest the potential influence of domain structures on the nucleation and progress of phase transitions, which unambiguously affect the hysteresis behavior of the first-order transition of VO2.

Optical Switching of Coherent VO2 Precipitates Embedded in Sapphire

1995 ◽  
Vol 396 ◽  
Author(s):  
L. A. Gea ◽  
L. A. Boatner ◽  
J. D. Budai ◽  
R. A. Zuhr
Keyword(s):  
Phase Transition ◽  
Vanadium Dioxide ◽  
Thermal Processing ◽  
Optical Switching ◽  
Optical Transmission ◽  
Structural Phase ◽  
Switching Behavior ◽  
New Type ◽  
Single Crystal Sapphire ◽  
Smart Surface

AbstractIn this work, we report the formation of a new type of active or “smart” surface that is produced by ion implantation and thermal processing. By co-implanting vanadium and oxygen into a single-crystal sapphire substrate and annealing the system under appropriate conditions, it was possible to form buried precipitates of vanadium dioxide that were crystallographically oriented with respect to the host AI2O3 lattice. The implanted VO2 precipitate system undergoes a structural phase transition that is accompanied by large variations in the optical transmission which are comparable to those observed for thin films of VO2 deposited on sapphire. Co-implantation with oxygen was found to be necessary to ensure good optical switching behavior.

Cr doping-induced structural phase transition, optical tuning and magnetic enhancement in BiFeO3 thin films

2017 ◽  
Vol 186 ◽  
pp. 198-201 ◽  
Author(s):  
Benlong Guo ◽  
Hongmei Deng ◽  
Xuezhen Zhai ◽  
Wenliang Zhou ◽  
Xiankuan Meng ◽  
...  
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Bifeo3 Thin Films ◽  
Magnetic Enhancement ◽  
Cr Doping
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