  We have prepared high-quality polycrystalline FeTe0.5Se0.5 at temperature as
low as 550{\deg}C. The transport critical current density evaluated by the
current-voltage characteristics is over 700 A/cm2 at 4.2 K under zero field,
which is several times larger than FeTe0.5Se0.5 superconducting wires. The
critical current density estimated from magneto-optical images of flux
penetration is also similar to this value. The upper critical field of the
polycrystalline FeTe0.5Se0.5 at T = 0 K estimated by
Werthamer-Helfand-Hohenberg theory is 585 kOe, which is comparable to that of
single crystals. This study gives some insight into how to improve the
performance of FeTe0.5Se0.5 superconducting wires.
