0.85PbMg 1/3Nb 2/3O 3-0.15PbTiO 3 (0.85PMN-0.15PT) ferroelectric relaxor thin films have been deposited on La 0.5Sr 0.5CoO 3/(111) Pt/TiO 2/SiO 2/Si by pulsed laser ablation by varying the oxygen partial pressures from 50 mTorr to 400 mTorr. The X-ray diffraction pattern reveals a pyrochlore free polycrystalline film. The grain morphology of the deposited films was studied using scanning electron microscopy and was found to be affected by oxygen pressure. By employing dynamic contact-electrostatic force microscopy we found that the distribution of polar nanoregions is majorly affected by oxygen pressure. Finally, the electric field induced switching in these films is discussed in terms of domain wall pinning. Copyright © Taylor & Francis Group, LLC.