Internal friction in nb-v-o alloys

Abstract

The logarithmic decrement, δ, was measured in Nb-V-O alloys with the V content of 0.5, 1.0, 1.9, 7, 12, 20 and 50 at.% using a low frequency (f= 3-7 Hz) inverse torsion pendulum in the temperature range from 20 to 800°C. The complex oxygen atom Snoek peaks were analysed with the help of a computer and individual Debye form constituent peaks-jwere extracted. The parameters of these peaks were used to derive information of two sorts: (a) distribution of oxygen atoms over octahedral interstices which differ in the number jof V atoms in the nearest neighbour lattice sites (static parameter) and (b) the potential barriers for oxygen atoms diffusing from j-positions (dynamic parameter). The first was used to evaluate the binding energies of oxygen with vanadium atoms in jV-O complexes, the second made understandable the structure of potential barriers for diffusion of the oxygen atoms from positions j. The differences between measurements of static and dynamic characteristics are discussed.