7 Things You Should Know Before Embarking On Piezoelectric Ceramics
Piezoelectric ceramic has its own shortcomings: First, the coercive field (Ec) is too high，the first is not conducive to polarization; the second of piezoceramic crystal is low piezoelectric activity and low resistivity. In order to overcome these two defects, the main usage of PZT material piezoceramic crystal is high temperature polarization, as the coercive field decreases with increasing temperature and doping modification. Tadashi Takenaka is to achieve high impedance, Nb5 + and V5 + were doped with Bi4Ti3O12 (BIT). The results show that the densities of BITN (Bi4Ti3 - xNbxO12) and BITV (Bi4Ti3 - xVxO12) reach more than 95% of theoretical ones. The resistivity of BIT is 1010 ~ 1011 Ψ cm, while the BITN and BITV are about 1013 ~ 1014Ψcm ; Tc 650 C, k33 0.39. In addition, the Bi3TiTaO9 (BTT) group was also doped with Qm as high as 13,500. These properties determine the bismuth layer ceramic which is suitable for high frequency electronic piezo sensors, oscillators and filters. Lian Zhang added Bi 2 Ti 3 O 12 to form a layered Nb 2 O 5 layer and studied the ceramic properties at low temperature by sintering at x = 0. 02~0.20. The results show that the density of all the samples reaches 95% of the theoretical value, and no second phase is produced. Nb5 + doping reduces the grain size and limits the anisotropic growth. At x = 0.08 and 0.11, The best properties of Pzt piezo resonance frequency are high kp (0.36; 0.35), d33 (19.18PC / N), Qm2 348-2492, tan δ126.96.36.199%, ε / ε0 (181; 199) and Lead-free piezoelectric ceramics with a perovskite structure have a large d33> 300PC / N that relative to lead-free piezoelectric ceramics and are suitable to use as for drivers and high-power devices. However, the piezo transducer vibration has the disadvantages of low curie temperature, large coercive field and low relative density, which limits its application. The LEAF program in Europe from 2001 to 2004 requires the gradual removal of lead and heavy metals as of July 1, 2006, with emphasis on (Li, Na) NbO3 (LNN) and (K, Na) NbO3 (KNN) in the LEAF program.At present, the preparation of LNN and KNN is still very difficult, especially in terms of density 4%. Erling Ringgaard reported that Mg2 +, Ca2 +, Sr2 + doping can increase the sintering density; using fine grinding to produce nano-powder, the relative density of 99.1% ~ 99.4% prepared by sintering forging method. In addition to ANbO3-type perovskite piezoelectric ceramic, sodium bismuth titanate (Bi0. 5N a0. 5) TiO3 piezoelectric ceramics (referred to as BN T) is also the current lead-free piezoelectric ceramics research hot spots. It was first discovered in 1960 and has a perovskite structure. The same sodium bismuth titanate also has low piezoelectric activity, large coercive field and so on. At present, bismuth titanate sodium is modified mainly by adding various perovskite structure dopants.