A Study On The Ferroelectric Hysteresis Property Of PLZT Transparent Electro-optic Ceramics With Ions Dopping

Although PLZT ceramics have excellent electro-optical properties,the large ferroelectric hysteresis increases the difficulty in designing of optical devices,thereby its further applications limited.In this paper,Pb_0.91La_0.09(Zr_0.65Ti_0.35)_0.9775O₃（PLZT9/65/35）is used as the basic component.Ba²⁺and Nb⁵⁺are selected to partially replace Pb²⁺,together with oxygen-passing hot-pressing sintering process through solid-state reaction.The dielectric properties,transmittance,grain size,and phase structure of the as doped PLZT were investigated,and the changes in ferroelectric and electro-optical properties are especially concerned.The results of this study are listed below:（1）In the study of Ba²⁺substituted PLZT(Pb_0.91-xBa_xLa_0.09(Zr_0.65Ti_0.35)_0.9775O₃),it was found that with the increasing doping amount from x=0 to 0.01,0.02,0.04,the coercive field and the residual polarization value decreased significantly.When doping x=0.02,the residual polarization value showed 135.4%reduction,meanwhile,the quadratic electro-optic coefficient decreased slightly（43.9%）but still within the range of application.And the temperature at the maximum dielectric constant T_m decreases rapidly.（2）With the Nb⁵⁺doping amount in PLZT(Pb_0.91La_0.09(Zr_0.65Ti_0.35)_0.9775-5y/4Nb_yO₃)increases from y=0 to 0.010,0.015,the ferroelectric hysteresis reduced dramatically.When doping with y=0.010,the quadratic electro-optical coefficient decreased by54.8%,but the hysteresis decreased by 162.5%.（3）In the experiment of Ba²⁺/Nb⁵⁺co-doping,it was found that with the increase doping amount in PLZT(Pb_0.91-xLa_0.09Ba_x(Zr_0.65Ti_0.35)_0.9775-5y/4Nb_yO₃),the ferroelectric loop is obviously slimed which means the ferroelectric hysteresis effect is greatly reduced.When doping with small amount of Ba²⁺（x=0,0.01,0.02）,the co-doping samples show better reduction in ferroelectric hysteresis.When doping with large amount of Ba²⁺（x=0.04）,the Nb⁵⁺ion shows less effect in reducing the hysteresis but better in thermal stability.The results of the study proved very well the effects of Ba²⁺and Nb⁵⁺on reducing the hysteresis of PLZT.In addition to the above effects,the co-doped samples show better in thermal stability which is important in applications.