The biggest feature of piezoelectric ceramics

                            The biggest feature of piezoelectric ceramics

The biggest feature of piezoelectric ceramics is the positive and negative piezoelectricity. Positive piezoelectric vibration sensor means that under the action of mechanical external force, some dielectrics cause the relative displacement of the positive and negative charge centers in the medium to cause polarization, piezoelectric transducer datasheet is resulting in the opposite ends of the dielectric. In the case of external force is not too large, its charge density is proportional to the external force,piezoelectric disc crystal is following the formula: δ = d T. Where δ is the surface charge density, d is the piezoelectric strain constant, and T is the stretching stress. On the other hand, when an external electric field is applied to a dielectric that is having a dielectric property, positive and negative charge centers of piezoelectric ceramics transducers within the dielectric body undergoes relative displacement and are polarized, whereby displacement causes the dielectric to deform. This effect is called reverse piezoelectricity. When the electric field is not very strong, the deformation is linear with the external electric field and follows the formula: x = d t E. d t ,which is the inverse piezoelectric strain constant, that is, the transpose matrix of d, E of hifu ultrasound piezo is the applied electric field, and x is the strain. The strength of the piezoelectric effect reflects the degree of coupling between the elastic properties of the crystal and the dielectric properties,which is expressed as the electromechanical coupling coefficient K, following the formula K = u 2 12 u1 u2. where u 212 is the piezoelectric energy and u1 is the elasticity. u2 is for dielectric energy. However, the disadvantages of these methods are that PbO which is easily volatilized, electrical piezoelectric sensor is causing the second phase, and the production process is difficult. In order to overcome these deficiencies, some methods have been proposed: calcination, adding perovskite additives.