Geometric considerations of the monoclinic–rutile structural transition in VO2

The mechanism of the displacive phase transition in VO2 near the transition temperature is discussed in terms of a geometrical approach, combining simple calculations based on the Brown's band valence model and in situ X-ray diffraction experimental results. Considering that the structural orig...

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Bibliographic Details
Published in:Dalton transactions : an international journal of inorganic chemistry 2019-06, Vol.48 (25), p.9260-9265
Main Authors: Guan, Shian, Rougier, Aline, Suchomel, Matthew R, Penin, Nicolas, Bodiang, Kadiali, Gaudon, Manuel
Format: Article
Language:English
Subjects:
Allotropy
Chemical Sciences
Material chemistry
Optimization
Phase transitions
Rutile
Thermal expansion
Transition temperature
Unit cell
Vanadium oxides
X-ray diffraction
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Summary:The mechanism of the displacive phase transition in VO2 near the transition temperature is discussed in terms of a geometrical approach, combining simple calculations based on the Brown's band valence model and in situ X-ray diffraction experimental results. Considering that the structural origin is well linked to the electrostatic potential optimization as in a Peierls model, our geometrical calculations and experimental studies are in agreement and suggest that VO2 phase transition is the consequence of very short atomic shifts mainly associated to a decrease of the 2nd sphere coulombic interactions. Hence, at a given temperature, the allotropic form (monoclinic versus rutile form) offering the largest unit-cell volume is stabilized over the lower unit-cell volume allotropic, while the transition occurs at the intercept of the unit cell variation versus temperature of the two forms, which exhibit significantly different thermal expansion coefficients.
ISSN:1477-9226
1477-9234
DOI:10.1039/c9dt01241a