Oil saturation effects in lead metaniobate porous piezoceramic: transient material characteristics

Lead metaniobate PbNb₂O₆ (PN) has a unique combination of high piezoelectric anisotropy; relatively low dielectric permittivity and high Curie temperature; and a low Q-factor, near 20. The very low Q-factor is the most intriguing PN property among the piezoelectric materials, and as shown in this research, this internal high dissipation and damping effect is directly related to the presence of silicon oil in the porous PN structure; consequently, it is dependent on the oil properties. To the contrary, the quality factor of PN not saturated with oil was found to be as high as nearly 400. Full sets of PN electro-mechanical constants, transient resonance and dissipation characteristics, and their temperature dependencies were determined under both conditions: PN conventionally saturated with oil and PN not saturated with oil. As was experimentally shown, at higher temperatures particularly after a 260°C soak for several days, a transition from the “with oil” state to the “no oil” state takes place in the conventional PN properties; this effect is a consequence of the phase transition in the silicon oil from liquid to solid state.