Piezoelectric　ceramics　system　of　Pb((Zn1/3Nb2/3)(0.20)(Zr0.50Ti0.50)(0.80))O-3　(0.2PZN-0.8PZT)　was　prepared　by　the　conventional　oxide　mixing　method.　The　dependences　of　the　internal-bias　field　and　electric　properties　on　the　sintering　temperature　were　investigated　systematically.　The　results　indicated　that　the　perovskite　structure　was　stable　in　a　wide　sintering　temperature　region.　The　rise　of　sintering　temperature　favored　the　enlargement　of　the　grain　size,　while　showing　a　slight　effect　on　tetragonal　distortion　c/a.　The　dissymmetrical　shape　of　polarization-electric　field　hysteresis　loops　was　displayed　in　all　specimens,　indicating　the　existence　of　internal-bias　field　(E-i).　With　the　increase　of　sintering　temperature,　E-i　sharply　decreased　to　0.84　kV　cm(-1)　at　1000　degrees　C　then　increased,　while　the　remnant　polarization　(P-r)　was　found　to　show　the　inverse　trend.　The　derivative　effects　of　the　sintering　temperatures,　involving　the　internal-bias　field　effect　and　grain-size　effect,　affected　the　ferroelectric　and　piezoelectric　properties　of　0.2PZN-0.8PZT.　(C)　2012　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim