Phase coexistence and pressure-temperature phase evolution of VO2(A) nanorods near the semiconductor-semiconductor transition

Abstract

A comprehensive understanding of the physical origins of the phase transition behaviors of transition metal oxides is still complex due to the interplay among competing interactions of comparable strengths tuning their nature. Widespread interest in such phase transitions has motivated explorations of nanocrystalline vanadium dioxide (VO 2) in various forms and a long-running debate persists over the roles played by electron-electron correlation with lattice distortion. External stimuli like pressure and temperature have strong effects on the appearance, stability, and spacial distribution of the high-resistive (HR) and low-resistive (LR) phases accompanying their structural modification. Our comprehensive experiments establish the pressure-induced and thermally driven evolution of phase coexistence in VO 2 (A) nanorods. Our experimental evidence supports coexisting HR and LR phases, where compression suppressed coexistence at ∼7 GPa, followed by a semiconductor-semiconductor transition at around ∼10 GPa with the absence of pressure-induced metallization. X-ray diffraction revealed lattice distortion with local microscopic strain inhomogeneity in the nanorods, without any discontinuity in the pressure-volume data. We further investigated the vibrational modes and relaxations of the samples related to their thermal expansions. We also found that the pressure-dependent hierarchy of microstructural densification contributed significantly to the resulting transport properties.

First-Order Isostructural Phase Transition Induced by High Pressure in Fe(IO3)3

“…Upon decompression, we did not collect intermediate points from the highest pressure to ambient pressure; thus, we cannot discuss if there is hysteresis or not in the transition. Phase coexistence has been observed in many other oxides under HP. , The reasons for it could be multiple. An argument recently proposed to explain it is the presence of kinetic barriers, which could be locally overcome by the presence of defects which provide a kinetic pathway of the phase transition …”

“…Phase coexistence has been observed in many other oxides under HP. 43,44 The reasons for it could be multiple. An argument recently proposed to explain it is the presence of kinetic barriers, which could be locally overcome by the presence of defects which provide a kinetic pathway of the phase transition.…”

Building Low-Cost, High-Performance Flexible Photodetector Based on Tetragonal Phase VO2 (A) Nanorod Networks

“…Both theory and experiments have revealed that VO 2 (A) nanowires can be employed as H 2 S gas sensors, showcasing exceptional selectivity and reproducibility [18]. The structural evolution of VO 2 (A) NRs under pressure reveals information about the VO 2 (A) phase transition [19]. Through an analysis of the electrical properties of VO 2 (A), its distinctive field emission characteristics have been elucidated [20].…”