Crystal Structures and Transition Mechanism of VO2(A)

✍ Scribed by Yoshio Oka; Shoichi Sato; Takeshi Yao; Naoichi Yamamoto

• Book ID: 102975498
• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 545 KB
• Volume: 141
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1998.8025

✦ Synopsis

Structures of VO 2 (A) have been redetermined by single-crystal diffractometry for low-(LTP) and high-temperature (HTP) phases at 298 and 473 K, respectively. The LTP adopts the tetragonal system P4/ncc with a ‫؍‬ 8.4403(9) A > , c ‫؍‬ 7.666(1) A > , and Z ‫؍‬ 16, whereas the HTP adopts the body-centered tetragonal system I4/m with a ‫؍‬ 8.476(2) A > , c ‫؍‬ 3.824(2) A > , and Z ‫؍‬ 8. The refinements led to R/R w ‫؍‬ 0.031/0.032 for LTP and 0.012/0.033 for HTP. The structures of both phases consist of edge-sharing VO 6 octahedra and exhibit quite similar oxygen frameworks. Through the transition the V 4 ؉ -V 4؉ bonding in LTP with a distance of 2.7695(8) A > is dissociated in HTP to a distance of 3.0794(3) A > . The transition occurs with cooperative movements of the V atoms, namely, a rotation around the c axis and a shift along the c axis. Strangely, twinning is induced on the LTP to HTP transition but disappears on the reverse transition.