CRYSTALLOGRAPHIC, THERMOGRAVIMETRIC AND MAGNETIZATION STUDY OF THE YBA2CU3-XFEXOY SUPERCONDUCTOR (0 LESS-THAN-OR-EQUAL-TO X LESS-THAN-OR-EQUAL-TO 0.2, 6 LESS-THAN-OR-EQUAL-TO Y LESS-THAN-OR-EQUAL-TO 7)

A systematic study is presented of the lattice parameters and the transition temperature T(c) of the YBa2Cu3-xFe(x)O(y) superconductor as a function of both the iron and the oxygen content. The system undergoes an orthorhombic to tetragonal structural transition with increasing iron content, however remaining superconducting. The T(c) values of the doped samples are rather sensitive to their oxygen content, since the 55 +/- 5 K plateau of the undoped system (6.5 less-than-or-equal-to y less-than-or-equal-to 6.7) does not persist with increasing iron content and none of the samples with x greater-than-or-equal-to 0.1 is superconducting for y < 6.64. The influence of the iron doping in the oxygen content of the system is also discussed.