Investigation Of Electromechanical Properties In Manganese Doped PIN-PMN-PT Single Crystals

Relaxor ferroelectric single crystals have attracted a lot of attention in the field of ferroelectric research due to their excellent properties.In which,ternary relaxor ferroelectric single crystals Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-Pb Ti O3(PIN-PMN-PT)and Mn doped PIN-PMN-PT(PIN-PMN-PT:Mn)have not only high piezoelectric and dielectric properties,but also high phase transition temperature and high coercive electric field,which make them widely used in various fields.In recent years,most of the researches focus on the mechanism of high performance from the perspective of intrinsic lattice distortion at room temperature,but few on the temperature stability of electromechanical properties and the relationship between domain wall dynamics and electromechanical properties.Therefore,the heat generation of the device in use and the influence of domain wall motion on its performance can't be ignored,the PIN-PMN-0.27 PT and PIN-PMN-0.27PT:Mn single crystals are the objects of the study,in this paper,the stability of its electromechanical properties and the fatigue characteristic are mainly studied in the following aspects.The stability of electromechanical properties with temperature of [011]C-oriented PIN-PMN-0.27PT:Mn were studied.Through the measurement of the piezoelectric coefficients,the dielectric constants,the electromechanical coupling coefficients and the elastic constants with the change of temperature of single domain and “2R” engineering domain structure single crystals,It is found that the electromechanical properties of the single crystal did not change with the change of orientation,and increased with the increase of temperature before the transformation temperature.Using the coordinate transformation method,the intrinsic longitudinal and shear piezoelectric properties on the temperature dependence of [011]C-oriented PIN-PMN-0.27PT:Mn single crystal were calculated.Then by comparing the experimental data with the theoretical calculation data,the reasons of the change of the electromechanical properties with the temperature of the [011]C-oriented single crystal were analyzed.The results show that the change of the longitudinal piezoelectric properties with temperature is mainly caused by the changeof the intrinsic lattice distortion with temperature,while the change of the shear piezoelectric properties with temperature is the result of the interaction of the intrinsic lattice distortion and other extrinsic factors.The domain wall dynamics and electromechanical properties of [011]C-oriented PIN-PMN-0.27 PT and PIN-PMN-0.27PT:Mn single crystals were investigated.The contribution of intrinsic lattice distortion and extrinsic domain wall motion to the dielectric response was quantitatively analyzed by Rayleigh method.The results show that Mn doping inhibited the domain wall motion to some extent.And that the reversible and irreversible extrinsic dielectric responses in the unpoled samples inhibited to 27% and 14% with Mn,while the irreversible one is decreased to 34% after poling.Compared with the situation in [001]C-oriented samples,the inhibition of domain wall motions and restriction on polarization switching are weak,resulting in low Qm enhancement in the 2R domain structure than that in the 4R structure,and piezoelectricity decreases slightly.This study depicts the domain wall dynamics and their relationship with mechanical quality factors and dielectric and piezoelectric properties and also provides some relevant information on further optimization of Pb Ti O3-based single crystals.The fatigue characteristic of [011]C-oriented PIN-PMN-0.27 PT and PIN-PMN-0.27PT:Mn single crystals were investigated.It was found that the ferroelectric properties of two samples decreased with the increase of the number of cycles,which was mainly reflected in the decrease of saturation polarization and remnant polarization,and the coercive field of the undoped Mn sample increased with the increase of the number of cycles.By comparing the experimental results of [001]C orientation,it is found that the effect of Mn doping on fatigue properties is anisotropic.Then the electromechanical properties before and after fatigue test were characterized,it was found that Mn doping improved its fatigue resistance.