Changing the properties of doped vanadium dioxide during prolonged storage under natural conditions

The article compares the results of X-ray diffraction, electric and magnetic studies, as well as the heat capacity of samples of solid solutionsV1−xFexO2 and V1−xAlxO2 and the same samples after their long storage at ordinal conditions. The appearance of reflexes, allegedly belonging to the phases of V2O5 and iron oxide (aluminum), was fixed by the X-ray diagrams of “stored” samples. It was found a significant change in the electrical and magnetic properties of materials and less noticeable changes in the heat capacity of the metal-semiconductor phase transition. The results are discussed in the terms of the active collisions model. It is concluded about the deformation of the conduction band and, as a consequence, the reduction of the electronic states density near the Fermi level for the “stored” samples.