The Investigation Of Low Temperature Sintering Of PNN-PZT Ceramics Materials

With the development of portable electronic products toward the small, light, thindirection, multi-layer chip structure in terms of piezoelectric transformers, speakers andfilters are widely used. The match between the ceramic material and the inner electrode isone of the key technologies. In view of the inner electrode with the characteristics of thebase metal silver high conductivity, low melting point（960℃）, the ceramic material whichis co-fired with it must have properties as follows: high-voltage constant d₃₃, highelectromechanical coupling coefficient K_p, low dielectric loss tanδ and low mechanicalquality factor Q_m and electrical properties, at the same time, a lower sintering temperatureis requested, too. In order to lower sintering temperature, all of the researches are done onPb(Ni_1/3Nb_2/3)O₃-Pb（Zr,Ti）O₃piezoelectric ceramics.First of all, the study on the properties of the system PNN-PZT with different Zr/Tiratio and PNN content indicated the best porperties. The results show that, when the Zr/Tiratio is41/59and the PNN content is0.35, we got the highest dielectric and piezoelectricproperties. The main parameters are: d₃₃=538pC/N，K_p=0.62，Q_m=61，ε₃₃^T/ε₀=3381，tanδ=0.0161.Then, xwt.%0.5Pb0-0.5B₂O₃and0.1wt.%CuO-xwt.%LiBiO₂were added in PNN-PZTdesperately to lower the sintering temperature. We study how the sintering behavior, phasestrucrue, microstructrue and electrical properties changed with the change of the content ofsintering aids. The results show that: when the content of0.5Pb0-0.5B₂O₃is0.5wt.%, theceramic got the best properties at the sintering temperature of1060℃: d₃₃=479pC/N，K_p=0.55，Q_m=79，ε₃₃^T/ε₀=2904，tanδ=0.0166；when the content of LiBiO₂is1wt.%, theceramic got the best properties at the sintering temperature of1000℃: d₃₃=538pC/N，K_p=0.62，Q_m=61，ε₃₃^T/ε₀=3381，tanδ=0.0161。Lastly, since the sintering temperature is still higher than the volatilization temperatureof PbO, PbO can volatilize during the sintering. The infuce of excess PbO on properties ofpiezoelectric ceramics were0.35Pb(Ni_1/3Nb_2/3)O₃-0.65Pb(Zr_0.41Ti_0.59)O₃also disucced. The sintering temperature can be reduced to980℃, and the properties were higher: d₃₃=567pC/N， K_p=0.61，Q_m=62，ε₃₃^T/ε₀=3442，tanδ=0.0154.