The　effects　of　atmospheric　powder　on　microstructure　and　piezoelectric　properties　of　Pb(Mn1/3Nb2/3)O-3-Pb(Zn1/3Nb2/3)O-3-PbZrO3-PbTiO3　(PMZN-PZT)　quaternary　ceramics　were　investigated.　Specimens　with　various　contents　of　Pb(Mn1/3Nb2/3)O-3　from　0　to　20　mol%　were　prepared　by　columbite,　two-stage　process　with　and　without　atmospheric　powder　of　PbZrO3.　The　results　revealed　that　the　atmospheric　powder　is　favored　to　the　liquid-state　sintering　process　in　PbO　vapor　pressure　equilibrium.　The　specimen　sintered　with　atmospheric　powder　is　homogenous　and　the　fracture　is　intergranular.　However,　the　specimen　sintered　without　atmospheric　powder　is　less　homogenous　and　the　fracture　is　essentially　transgranular.　On　the　other　hand,　the　pyrochlore　phase　was　formed　along　with　the　perovskite　phase　for　the　specimens　sintered　without　atmospheric　powder　and　the　second　phase　was　seriously　detrimental　to　the　electromechanical　properties.　The　superior　piezoelectric　properties　were　observed　for　the　specimens　sintered　with　atmospheric　powder.　By　optimizing　the　specimen　composition,　excellent　piezoelectric,　and　dielectric　properties　(Q(m)　=　2528,　K-p　=　0.55,　tan　delta　=　0.003)　were　obtained　at　10　mol%　Pb(Mn1/3Nb2/3)O-3　(C)　2004　Elsevier　Ltd.　All　rights　reserved.