Abrupt Negative Thermal Expansion and Magnetic Structure of V3O5

International audience; We report bulk dilatometry and diffraction data through the T MIT = 427 K metal-insulator transition of the n = 3 member of the V n O 2n-1 Magnéli series. Besides VO 2 , V 3 O 5 is the only other vanadium oxide with a potentially useful MIT transition above room temperature. A narrow (ΔT = 10 K) abrupt negative thermal expansion of α L =-21.4 x 10-6 (dilatometry) and α V =-213 x 10-6 K-1 (crystallographic) is observed. We argue that the combination of the MIT along with the simultaneous vanadium charge ordering are responsible for such large values. The low temperature magnetic properties are also clarified and neutron diffraction measurements show a k = [½ ½ 0] magnetic structure at 1.5 K. DFT calculations of the exchange interactions support the low dimensionality and allow modelling the magnetic susceptibility.