Nb₃Sn superconductors have been fabricated through a new process starting from Nb₆Sn₅ intermediate compound powder. The mixed Nb₆Sn₅ and Nb powder is encased in a Ta tube, and rolled into tapes without annealing and then heat treated. The Nb₆Sn₅ compound powder can be easily synthesized by melt-diffusion reaction at 900°C between Nb and Sn powders. The Nb₃Sn fabricated by this process has a large ρ_n value and a B_c2 of 24.7T at 4.2K, which is considerably higher than that of bronze-processed Nb₃Sn. In this study, the effects of different additional elements on the high-field performance of the new Nb₃Sn specimen were studied. The J_c (core) of the specimen with 2at% Ti substitution for Nb is 3.2×10⁴A/cm² at 20T and 4.2K. The addition of Cu to the specimen decreases the optimum heat-treatment temperature from 900-925°C to 850°C. The addition of a small amount of Ge or the substitution of a small amount of Ta for Nb raises the curvature of the log J_c-B curves of specimens to a convex at high magnetic fields, resulting in significant enhancement in high-field performance. The Nb₃Sn specimen with the addition of 1.0wt% Ge and a slightly richer Sn concentration shows a J_c (core) of 3.2×10⁴A/cm² at 21T and 4.2K. The small amount of Ta substitution for Nb has been found to be most effective to achieve large J_c at high magnetic fields. The optimum amount of Ta substitution is 5-7at%. The J_cS (core) of the specimen with 5at% Ta at 22 and 23T at 4.2K are 3.3×10⁴ and 2.4×10⁴A/cm², respectively. The specimens with Ta substitution are composed of two Nb₃Sn phases with different Ta concentrations. The new Nb₃Sn superconductors may be quite attractive for high-field applications after multifilamentary-type conductors with Cu stabilizers become available.