Issue 15, 2011

Distinctive finite size effects on the phase diagram and metal–insulator transitions of tungsten-doped vanadium(iv) oxide

Abstract

The influence of finite size in altering the phase stabilities of strongly correlated materials gives rise to the interesting prospect of achieving additional tunability of solid–solid phase transitions such as those involved in metal–insulator switching, ferroelectricity, and superconductivity. We note here some distinctive finite size effects on the relative phase stabilities of insulating (monoclinic) and metallic (tetragonal) phases of solid-solution WxV1−xO2. Ensemble differential scanning calorimetry and individual nanobelt electrical transport measurements suggest a pronounced hysteresis between metal → insulator and insulator → metal phase transformations. Both transitions are depressed to lower critical temperatures upon the incorporation of substitutional tungsten dopants but the impact on the former transition seems far more prominent. In general, the depression in the critical temperatures upon tungsten doping far exceeds corresponding values for bulk WxV1−xO2 of the same composition. Notably, the depression in phase transition temperature saturates at a relatively low dopant concentration in the nanobelts, thought to be associated with the specific sites occupied by the tungsten substitutional dopants in these structures. The marked deviations from bulk behavior are rationalized in terms of a percolative model of the phase transition taking into account the nucleation of locally tetragonal domains and enhanced carrier delocalization that accompany W6+ doping in the WxV1−xO2 nanobelts.

Graphical abstract: Distinctive finite size effects on the phase diagram and metal–insulator transitions of tungsten-doped vanadium(iv) oxide

Supplementary files

Article information

Article type
Paper
Submitted
08 Nov 2010
Accepted
13 Jan 2011
First published
15 Feb 2011

J. Mater. Chem., 2011,21, 5580-5592

Distinctive finite size effects on the phase diagram and metal–insulator transitions of tungsten-doped vanadium(IV) oxide

L. Whittaker, T. Wu, C. J. Patridge, G. Sambandamurthy and S. Banerjee, J. Mater. Chem., 2011, 21, 5580 DOI: 10.1039/C0JM03833D

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