Ni Zhong

Single-calcination synthesis of pyrochlore-free Pb(Ni1/3Nb2/3)O3–PbTiO3 using a coating method

Abstract Pyrochlore-free 0.64Pb(Ni 1/3 Nb 2/3 )O 3 –0.36PbTiO 3 (0.64PNN–0.36PT) powder has been successfully synthesized by only one calcination step using a coating method. The formation of pyrochlore phase is prevented by coating NiCO 3 ·2Ni(OH) 2 ·2H 2 O on Nb 2 O 5 particles. NiCO 3 ·2Ni(OH) 2 ·2H 2 O-coated Nb 2 O 5 powder is prepared by heterogeneous precipitation method. The coating structure is confirmed by transmission electron microscope (TEM) with energy dispersive spectroscope (EDS). Single calcination treatment of the coating powder mixed with appropriate amounts of Pb 3 O 4 and TiO 2 powders at 900 °C for 2 h produces the pure-perovskite 0.64PNN–0.36PT powder. The elimination of the pyrochlore phase can be explained in terms of the separating of Pb 3 O 4 and Nb 2 O 5 by the NiCO 3 ·2Ni(OH) 2 ·2H 2 O coating layer.

Dielectric Breakdown Properties of Zr-Rich Lead Zirconate Titanate Ceramics

The series Nb-doped zirconate-rich lead zirconate titanate (PZT) ceramics with high densities up to 97% were fabricated using the traditional solid reaction method. We investigated the dielectric breakdown strength of the series PZT ceramics and detected first that the dielectric breakdown strength increased with an increase in Zr/Ti at the boundary of the antiferroelectric and ferroelectric phases. A qualitative analysis was carried out to discuss the observed phenomena. The relationship between dielectric breakdown and microstructure was also discussed.