In-situ monitoring of vanadium dioxide formation using high-temperature XRD

The monoclinic-to-tetragonal phase transition (~70 °C) in vanadium dioxide (VO 2 ) strongly impacts the infrared properties, which enables its use in applications such as smart window devices. Synthesis of VO 2 can be challenging due to the variability of vanadium oxide phases that may be formed. We have employed high-temperature X-ray diffraction (HTXRD) to monitor the reaction process of vanadium oxide precursor powders to form the desired tetragonal VO 2 phase. Single-phase tetragonal VO 2 was formed within 30 min at 420 °C in flowing N 2 gas (~50 ppm O 2 ). The monoclinic-to-tetragonal phase transformation was observed via HTXRD at ~70 °C with the typical ~10 °C hysteresis (i.e. approached from above or below the transition).