  MgB2 thin films were cold-grown on sapphire substrates by pulsed laser
deposition (PLD), followed by post-annealing in mixed, reducing gas, Mg-rich,
Zr gettered, environments. The films had Tcs in the range 29 K to 34 K, Jcs
(20K, H=0) in the range 30 kA/cm2 to 300 kA/cm2, and irreversibility fields at
20 K of 4 T to 6.2 T. An inverse correlation was found between Tc and
irreversibility field. The films had grain sizes of 0.1-1 micron and a strong
biaxial alignment was observed in the 950C annealed film.
