Exponential contribution to the electric resistance of the superconducting compound Nb3Al/sub 0.75/Ge/sub 0.25/ and the anomalous temperature dependence of its crystal-lattice parameter

Results are presented of measurements of the temperature dependence of the electric resistance (61--300 K) and of the crystal-lattice parameter (70--310 K) of a high-temperature superconducting compound Nb3Al/sub 0.75/Ge/sub 0.25/ with A15 lattice. It is shown that an important contribution to the resistance is made by scattering of electrons by phonons that correspond to the low-frequency peak of the density of states. The scattering can be expressed by a term exp(-T0/T), where T0 = 117.0 +- 6.8 K. The temperature dependence of the thermal expansion coefficient is found to change abruptly at Tapprox.T0. No lowering of the crystal-lattice symmetry of Nb3Al/sub 0.75/Ge/sub 0.25/ is observed