Abstract
In the given work results of researches of the thermodynamic parameters received from temperature dependence of a thermal capacity are resulted. It is shown, that on polyterms of a thermal capacity the maximum showing on existence of phase transition is observed. Results of the given researches are interpreted on the basis of effect YanТеller for ion V4+ tetrahedral coordination. For group of a tetrahedron where there is V4+ an ion, there are trigonal-independent displacement that explains essence of phase transi- tion in connections, i.e. structural phase transition is not observed, but there is a displacement crystal sublat- tice, for removal of degeneration of a condition, as results in observable anomaly on dependence Cp= f (Т).