The　formation　of　secondary　phase　in　4.0　mol.%　NiO-added　Pb(Zn1/3Nb2/3)O-3-PbZrO3-PbTiO3　(PZN-PZT)　ceramics,　prepared　by　a　conventional　solid-state　reaction　method,　was　investigated.　The　results　reveal　that　the　segregated　secondary　phase　in　perovskite　matrix　was　(Zn,Ni)TiO3　with　hexagonal　ilmenite　structure,　not　the　normally　predicted　NiO　or　ZnO.　A　new　formation　mechanism　related　to　the　enrichment　of　ZnO,　NiO　and　TiO2　at　grain　boundaries　has　been　proposed.　Due　to　its　non-ferroelectric　structure,　the　occurrence　of　(Zn,Ni)TiO3　greatly　deteriorates　the　piezoelectric　properties.　(C)　2013　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.