  In this work we have investigated the orthorhombic to tetragonal phase
transition in the Ba2Cu3O4Cl2 compound. This transition was observed by X-ray
powder diffractometry carried out in samples heat treated between 700 and 750OC
and also in samples with Ba2ZnCu2O4Cl2 composition. Results of X-ray
diffractograms simulation confirm the phase transition. dc-Magnetization
measurements performed in SQUID showed the existence of diamagnetism signal.
The results suggest the existence of localized superconductivity and can
explain the different magnetic properties reported in literature for the
Ba2Cu3O4Cl2 compound.
