Pulsed-laser deposited (Pb,Sr)TiO3 (PSrT) films on Pt/SiO2/Si substrate deposited at various oxygen partial pressures (P-O2), ranging from 50 to 200 mTorr, were investigated in this work. PSrT films exhibit (100) preferred orientation at lower P-O2 and then transit to (110) preferred orientation above 100 mTorr. The paraelectricity/ferroelectricity transition and dielectric constant of PSrT films are associated with the preferred orientation and oxygen concentration at various P-O2. Furthermore, films deposited at higher P-O2 exhibit higher breakdown field and smaller leakage current density as a consequence of fewer oxygen vacancies. Except for the case of films deposited at 200 mTorr, the conduction mechanism is identified as Schottky emission/Poole-Frenkel emission at low/high electric fields. (c) 2007 The Electrochemical Society.