| Relaxor ferroelectric lead magnesium niobate-lead titanate Pb(Mg1/3Nb2/3)O3-Pb Ti O3（PMN-PT）is a photoelectric functional material with excellent piezoelectric,electro-optic,energy storage and luminescence properties.It has been successfully applied in medical ultrasound diagnosis,underwater acoustic transducer,precision drive,electro-optic modulation and other fields.Previous studies have shown that the properties of the material can be very different by changing the solid solution ratio of PMN and PT,the type and concentration of doping elements,etc.,which provides rich possibilities for material optimization to improve performance and application in various fields.At present,the phase diagram of PMN-PT has been clarified,and the doping modification of a single element has also been widely studied.However,by changing the composition or introducing a certain doping element,only part of the properties of the material can be improved,and it is difficult to achieve synergistic improvement of multiple properties.In this paper,the effects of single element doping and double element co-doping on the structure and properties of PMN-PT ceramics were studied.The influence mechanism of doping on crystal structure and material properties was discussed,and the application research was carried out based on the prepared high-performance PMN-PT transparent ceramics.The specific research work includes:（1）The structure and properties of single element（La,Sm）doped PMN-PT ceramics were studied.PMN-12PT:0.5La transparent electro-optic ceramics were prepared,with a transmittance of 70.5%（close to the theoretical transmittance limit）and a secondary electro-optic coefficient of 25×10-16 m2 V-2,which can meet the practical application requirements.PMN-30PT:2.5Sm transparent piezoelectric ceramics were prepared.The transmittance was 64.91%,the piezoelectric coefficient was 1323 p C N-1,and the photoluminescence color was orange-red,which realized the synergistic improvement of electrical and optical properties.（2）The structure and properties of PMN-30PT ceramics co-doped with two elements（Sm and X）were studied,which provided experimental basis for rational design of element co-doping system.The piezoelectric coefficient of ceramics is the largest when Sm and La are co-doped.When Sm and Yb are co-doped,the energy storage efficiency of the ceramics is the largest,the transmittance is the highest,and the luminescence performance of the matrix is enhanced.When Sm and Mn are co-doped,the Curie temperature of the ceramics is the highest,the dielectric loss is the smallest,and the luminescence quenching occurs.（3）The effects of Mn doping concentration on the structure and properties of PMN-30PT:2.5Sm ceramics were studied.PMN-30PT:2.5Sm,1.5Mn ceramics have the most obvious acceptor doping characteristics,the highest Curie temperature and mechanical quality factor;the hysteresis loops of the samples with Mn doping concentrations of 2.5and 3.0 mol%show a’beam waist’shape,and a model of spontaneous polarization and defect polarization is established to explain this phenomenon.The hysteresis loops of PMN-30PT:2.5Sm,2.5Mn ceramics were continuously tested by changing the frequency.It was found that the synergistic doping of Sm and Mn was beneficial to the activation of oxygen vacancies,which accelerated the formation and orientation of defect dipoles.The energy storage characteristics of the material also showed frequency dependence,which provided a reference for the practical application of ferroelectric energy storage materials.（4）Using the prepared PMN-12PT:0.5La ceramic,the continuous conversion of laser polarization state under electric field regulation and the dual-channel free space optical communication with continuously adjustable light intensity are realized,which verifies the feasibility of the material as a polarization sensitive element or electro-optic modulation element in the field of optical communication. |
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