The distribution of porosity in Y1Ba2Cu3Oy (Y-123) pseudo-crystals prepared
by hot seeded melt growth of precursor pellet samples pre-sintered at elev
ated temperatures in air or vacuum has been investigated. The results demon
strate that the porosity within the Y-123 pseudo-crystal matrix could be re
duced dramatically by pre-sintering in vacuum, compared with that for precu
rsor pellets processed in air.