[en] Using the NGR method the effect of disordering and deviation from stoichiometry of superconducting compound Nbsub(3)Snsub(x) on temperature dependence of Debye-Waller factor in the temperature range 10-300 K in the samples: stoichiometric Nb₃Sn, Nbsub(3)Snsub(0.77) (annealing in Ar; Tsub(ann)=1700 deg C for 5 hr); Nbsub(3)Snsub(0.967) (annealing in Ar, Tsub(ann)=1300 deg C for 5 hr), has been investigated. A model, describing the obtained dependences of the Debye-Waller factor on temperature, is obtained. Moderating of acoustic modes of phonon spectrum of Nbsub(3)Snsub(x), correlating with the change in Tsub(c) in the process of Sn content change in Nbsub(3)Snsub(x), is detected. It is shown, that there is a correlation between concentrational dependence critical temperature Tsub(c) and anharmonity part Qsub(A)sup(10k)