Une transition métal-isolant dans V_0,90Nb_0,10O₂ due à un appariement local des atomes de vanadium

X-ray diffuse scattering from V_0.90Nb_0.10O₂ shows that the metal-to-insulator phase transition which occurs around - 25°C without an overall structural change can be explained by local pairing of the vanadium atoms. This local order, which recalls the low-temperature insulating structure of pure VO₂, is two dimensional and occurs in the (110) planes of the average rutile structure with little correlation between successive parallel (110) atomic planes.