Single　phase　polycrystalline　BiFeO3　thin　films　have　been　grown　on　Si　substrates　using　LaNiO3　as　buffer　layers　by　pulsed　laser　deposition.　A　transmission　electron　microscope　shows　an　amorphous　thin　layer　of　LaNiO3　followed　by　the　polycrystalline　LaNiO3,　which　facilitates　the　crystallization　of　a　BiFeO3　layer　in　R3c　structure　and　suppression　of　the　impurity　phases.　NiFe　layers　were　deposited　on　the　BiFeO3　layer　by　magnetron　sputtering.　Clear　exchange　coupling　between　BiFeO3　and　NiFe　(with　maximum　exchange　bias　field　up　to　61　Oe)　has　been　observed　at　room　temperature,　and　the　exchange　bias　field　decreases　with　increasing　the　NiFe　thickness.　Our　results　clearly　demonstrate　the　potential　application　of　polycrystalline　BiFeO3　in　magnetoelectric　coupling　based　spintronics.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.