piezoelectric constant
2.Single crystals have been grown with a boule size of ?40×70mm and plate size of 20×20×1mm 3. The dielectric constant ε is ～5000, loss tan δ<0.9%, piezoelectric constant d 33 >1500pC/N,and coupling k 33 ～94%.
3.Compared with NBT-BT6 specimen, the specimen added with proper amount of MnO shows a relative large increase of electromechanical coupling factor (kp) and significantly enhancedmechanical quality factor (Qm) accompanied by a relatively large decrease of piezoelectric constant (d33) and dielectric constant ( 33T/ 0) because of a "soft and hard" doping effect.
4.At this sintering temperature,the Curie temperature of the sample was 784℃,piezoelectric constant d33 and tanδ were 7.7×10-12C/N and 2.1×10-3,respectively. These results can be explained as follows: bismuth in the pseudo-perovskite blocks formed deficient layer easily at high sintering temperature which can lead to structure distortion and oxygen vacancies.
5.The experimental results show that the piezoelectric charge constant(d33),relative dielectric constant(εr) and dielectric dissipation loss factor(tanδ) decrease dramatically with increasing amount of doped Co2O3 in a rang from 0 to 0.4 %.
6.Electromechanical equation of piezoelectric crystal stack is derived from the piezoelectric equations of constant D and constant stress,but the acoustic speed of under the constant E is used in design in practical transducer design.
7.Due to dielectric constant of piezoelectric ceramic, ε c≈(1 600 ε 0)? ε p(≈12 ε 0),dielectric constant of polymer, E p was far more than E c.
8.The Eorror Analysis for the Substitution of Acoustic Speed under Constant E for Equivalent One in Piezoelectric Transducer Design
9.Piezoelectric composites was fabricated by using PVDF and five kinds of ceramic powder of different dielectric constant:PMN, PNL, PLS, P4-3, P8. Firstly, usin g N, N-Dimethyl formamide to dissolve PVDF, adding a certain proportion cerami c powder and drying it.
10.An increase in grain size increases the dielectric constant, piezoelectric coefficient and hydrostatic figures of merit, which can be explained by the Okazaki space-charge theory.
