Abrupt Negative Thermal Expansion and Magnetic Structure of V3O5

We report bulk dilatometry and diffraction data through the TMIT = 427 K metal-insulator transition of the n = 3 member of the VnO2n-1 Magne??li series. Besides VO2, V3O5 is the only other vanadium oxide with a potentially useful MIT transition above room temperature. A narrow (Delta T = 10 K) abrupt negative thermal expansion of aL = -21.4 x 10-6 (dilatometric) and aV = -213 x 10-6 K-1 (crystallographic) is observed. We argue that the combination of the MIT along with the simultaneous vanadium charge ordering is responsible for such large values. The low temperature magnetic properties are also clarified, and neutron diffraction measurements show a k = [1/2 1/2 0] magnetic structure at 1.5 K. DFT calculations of the exchange interactions support the low dimensionality and allow the modeling of the magnetic susceptibility.