Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO 2 Nanowires

Hasti Asayesh-Ardakani, Anmin Nie, Peter M. Marley, Yihan Zhu, Patrick J. Phillips, Sujay Singh, Farzad Mashayek, Ganapathy Sambandamurthy, Ke Bin Low, Robert F. Klie, Sarbajit Banerjee, Gregory M. Odegard, Reza Shahbazian-Yassar

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WVO nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122¯) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.
Original languageEnglish (US)
Pages (from-to)7179-7188
Number of pages10
JournalNano Letters
Volume15
Issue number11
DOIs
StatePublished - Oct 16 2015

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