Synthesis and magnetic field properties of transition metal substituted A-15 systems

摘要: We have been synthesizing high T c systems based on Nb 3 Ge in which another transition metal atom, either Mo, Ti, or Zr, is partially substituted for Nb. Systems prepared by selectively thermalized sputtering onto heated substrates. The investigated allow changes to be observed due a variation the electron per atom ratio as well size effects. Superconducting temperatures are measured inductively allows identification of homogenous samples. Sample composition analysis obtained quantitative X-ray fluorescence. For (Nb .99 Zr .01 ) 1-x x system measurements dHc 2 / dT fields up 10 resistive onset point went from 4.1 ±0.4 T/K 2.6±0.3T/K varied 0.24 0.19. At x=0.23 was 18.9k (H=0). Extrapolation 0 K no Pauli paramagnetic limiting gives H c2 (T = K) 54 ± 5 T.