Defects are known to affect nanoscale phase transitions, but their specific role in the metal-to-insulator transition in VO 2 has remained elusive. By combining plasmon resonance nanospectroscopy with density functional calculations, we correlate decreased phase-transition energy with oxygen vacancies created by strain at grain boundaries. By measuring the degree of metallization in the lithographically defined VO 2 nanoparticles, we find that hysteresis width narrows with increasing size, thus illustrating the potential for domain boundary engineering in phase-changing nanostructures. © 2012 American Chemical Society.
