The　quaternary　systems　0.74Pb(Zr0.47Ti0.53)O-3-0.26Pb[(Ni0.6Zn0.4)(1/3)Nb-2/3]O-3(PZT-PNZN)　have　been　prepared　using　the　conventional　oxide　mixing　method　in　a　wide　temperature　region　between　1050　and　1250　degrees　C.　All　specimens　present　high　relative　density　above　95%,　indicating　a　wide　sintering　window　for　this　system.　Investigation　of　the　microstructure　reveals　a　continuous　increase　in　grain　size　from　1.07　to　2.77　mu　m　when　the　sintering　temperature　is　increased　from　1050　to　1250　degrees　C,　which　obeys　the　common　grain-growth　law　well.　However,　unlike　compositional　component　PZN-PZT　and　PNN-PZT,　the　phase　structure　of　quaternary　PZN-PNZN　is　not　sensitive　to　the　grain　size.　The　specimens　with　different　grain　size　retain　the　morphotropic　phase　boundary　(MPB)　structure　and　the　size　induced　phase　transition　does　not　appear.　Excluding　the　influence　of　the　phase　structure,　the　size　effect　plays　a　dominant　role　in　improving　the　piezoelectric　properties,　which　facilitates　the　motion　of　domain　walls　due　to　the　decreasing　number　of　grain　boundary.　The　optimum　piezoelectric　parameters　are　obtained　at　1150　degrees　C:　d(33)　=　307　pC/N,　k(p)　=　0.56.　(C)　2014　Elsevier　B.V.　All　rights　reserved.