Abstract
Oxygen deficiency of Ba2YCu3O7-δ was studied by thermogravimetry and thermodilatometry. Ba2YCu3O7-δ rapidly releases and adsorbs oxygen even in temperature in the vicinity of 150°C. δ was controlled by cooling specimen in O2 gas flow after annealing in Ar gas atmosphere (O2/Ar annealing) and by Ar/O2 annealing. The lattice constants a and b in the O2/Ar annealed specimen show almost constant value in the range of 0<δ<0.7, while (a-b) in the Ar/O2 annealed specimen decreases with δ. Tc of Ar/O2 annealed sample differs from that of O2/Ar annealed sample even if the samples have the same value of δ.
