External electric fields on the PZT material

                                   External electric fields on the PZT material

TC increases with the increase of Mn doping amount, but the increasing amplitude of PZT material piezo ceramics becomes smaller and smaller and gradually becomes saturated. The variation law of TC may have the following two reasons: (1) Inner bias field and Ei inner bias .The generation of the field is generally caused by the space charge, which is enhanced by acceptor doping and donor doping Ei. For Mn, piezo ceramic stress sensor is because Mn 2+ and O 2- form an internal field opposite to the external electric field in the same direction as the spontaneous polarization. The piezoelectric transducers for wind velocity can weaken or cancel the influence of some external electric fields on the spontaneous polarization. Therefore, the hysteresis loop of the ferroelectric with the inner bias field needs to be removed by multiple inversions to get the accurate hysteresis loop. Ferroelectric phase change is the nature of structural changes, from the cubic phase into a square phase, high frequency piezoelectric transducer it is precisely because of the structural asymmetry will be formed by the spontaneous polarization,So it can be said that spontaneous polarization is the main feature of ferroelectric and concrete embodiment, ferroelectric phase transition means the spontaneous polarization is generated or disappeared. The internal bias field on the piezoelectric ceramic tonpilz transducer  (domain) has a stabilizing effect, it can also affect the ferroelectric phase transition. Therefore, TC increases with the increase of Mn doping. (2) The solubility of Mn enter into the main part of the piezoelectric ceramic to replace a part of the Pb2 + or B position of Ti4 + and Zr4 +, when it is the lower concentration of piezo sphere transducer.Mn mainly enter into the lattice and forming internal deviation place, on the spontaneous polarization has a stabilizing effect. As the Mn content increases, reaching its solubility that is into the grain boundary,which will not be re-enhanced Ei, that is, the internal bias field has been saturated, of course,that will not enhance the stability of the spontaneous polarization,it is TC with Mn.The increase of doping amount increases first and then gradually becomes saturated.