Low-temperature Sintering And Investigation Of PZT-PNN-PZN Quaternary Piezoelectric Ceramics

In recent years, multilayer piezoelectric ceramics have been intensively investigated for the complete machine integration, miniaturization, hybridization and high performance of the devices. There is a need to lower the sintering temperature for multilayer piezoelectric ceramic in order to co- fire them with less expensive metal electrodes such as pure Ag or high Ag/low Pd. Consequently, lowering of the sintering temperature of piezoelectric ceramics is essential for the fabrication of cost-effective multilayer piezoelectric devices. In this paper, three methods: non-stoichiometric, added CuO and was added new component were used to lower the sintering temperature of PZT-PNN-PZN quaternary piezoelectric ceramics. The effect of different methods on the microstructure, density, dielectric and piezoelectric properties of PZT-PNN-PZN quaternary piezoelectric ceramics were investigated.Firstly, The PZT-PNN-PZN quaternary piezoelectric ceramics was fabricated by the one-step method. the influence of the amount of Pb₃O₄?NiO?ZnO on the sintering characteristic and electrical properties of PZT-based quaternary piezoelectric ceramics was studied. The results show that the addition of Pb₃O₄?NiO?ZnO did not change the crystal structure of PZT-based quaternary piezoelectric ceramics, and the formed liquid phase promoted densification and reduced the sintering temperature during the sintering process. But the addition of Pb₃O₄?NiO?ZnO did not improve the electrical properties specimens. When 1mol% N i O excess, the PZT-PNN-PZN quaternary piezoelectric ceramics was fabricated by the two-step method, the piezoelectric constant d33, relative dielectric constant ?₃3^T/?0, dielectric loss tan? of specimen which was sintered at 950°C for 4h are as follows: d33=337pc/N, ?₃3^T/?0=2311.56, tan?=2.1%.And the different influence of adding NiO before and after the secondary composition for the sintering characteristics and properties of specimens. The results show that the specimens which NiO is added after the secondary composition have high-density structure and better electrical properties. The method of non-stoichiometric can lower the sintering temperature of PZT-PNN-PZN quaternary piezoelectric ceramics, but degrade electrical properties seriously.Then, in order to getting specimen which have excellent electrical properties in a low sintering temperature, a amount of CuO was added into PZT-PNN-PZN quaternary piezoelectric ceramics. The experimental results sho w that the add of CuO did not change the main crystal structure, and could clearly improve density. When 1mol% CuO was added into specimen, the piezoelectric constant d33, relative dielectric constant ?₃3^T/?0, dielectric loss tan? of specimen which was sintered at 950°C for 4h are as follows: d33=411pc/N, ?₃3^T/?0=2449, tan?=1.86%. The method of added CuO can lower the sintering temperature of PZT-PNN-PZN quaternary piezoelectric ceramics, at the same time have better electrical properties.Finally, Low-temperature sintering of?a-x?Pb(Zr_0.48Ti_0.52)O₃-b Pb(Ni_1/3Nb_2/3) O₃-c Pb(Zn_1/3 Nb_2/3)O₃-x Pb(Fe_2/3W_1/3)O₃?a+b+c+x=1, 0.06?x?0.10? ceramics were prepared through two-step synthesis process using perovskites-structured ferroelectric materials Pb(Fe_2/3W_1/3)O₃?PFW? as a sintering aid. The effects of PFW content on the the densification, microstructure, phase structure, dielectric and piezoelectric properties of the ceramics were investigated. The sintering temperature was reduced from 1180 °C?without PFW addition? to 940°C when the material was PFW-doped. PFW-doping increased the sintered density and the average grain size of PFW-PNN-PZN-PZT ceramics. The ceramics sintered at 940°C for 4h with x=0.08 exhibited favorable properties, which were listed as follows: d33=496p C/N, ?₃3^T/?0=3119, tan?=2.1% and Tc=242°C. These values indicated that the newly developed composition might be suitable for multilayer piezoelectric devices application.