An X-Ray Diffraction Study of Martensitic Transformation in Ti-Doped Nb₃Sn

The effect of titanium addition on the martensitic transformation in Nb₃Sn was investigated by low-temperature X-ray diffraction using small-sized (0.1–0.3 mm) high-quality single crystals. It has been found that addition of 0.2 at.% Ti lowers the transformation temperature, T_mby 3 K while further addition up to 1.5 at.% suppresses the transformation. T_mis very sensitive to the manner of sample adhesion to the cold end of the cryostat and it rises nearly to ambient temperature if improperly adhered. The axial ratio a/c of the 0.2 at.% Ti doped alloy was measured to be 1.001 at 30 K, which compares to a value of 1.005 for the undoped alloy. A tendency to form a single tetragonal domain with decreasing temperature through T_mfor the 0.2 at.% Ti doped alloy was observed.