Structure and electrical properties of Mn-modified Pb((Zn1/3Nb2/3)0.20 (Zr0.50Ti0.50)0.80)O3 ceramics sintered in a protective powder atmosphere

The effects of PbO atmosphere on structure and electrical properties of Mn-modified Pb((Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80)O3 ceramics were investigated. Specimens were prepared with and without a PbZrO3 protective ambient, by columbite two-stage process in a temperature region from 1050 to 1200 °C. The results indicated that PbZrO3 powder is favored to the liquid-state sintering process of specimens in PbO vapor pressure equilibrium. The specimens sintered with PbZrO3 powder showed the homogenous and intergranular microstructure; whereas, the specimens sintered without PbZrO3 powder demonstrated the inhomogenous and transgranular microstructure. Without protective PbZrO3 powder, the flow of PbO from the compact to the exterior resulted in the formation of amorphous phase in grain boundaries, which deteriorated the electric properties seriously. By the use of PbO protective atmosphere, the excellent piezoelectric and dielectric properties (Qm = 1160, tan δ = 0.004, Kp=0.54) were obtained at 1100 °C for 2 h.