Study Of Photoluminescence And Electric Properties Of Yb³⁺?Ho³⁺ Doped PMN-0.33PT Multifunctional Ceramics

Pb(Mg_1/3Nb_2/3)O_3-xPbTiO₃?PMN-x PT?ceramics exhibit excellent ferroelectric and piezoelectric properties,which are popular inrecent years.Compared with the traditional ferroelectric materials,PMN-PT single crystal and ceramics exhibited giant piezoelectric properties.PMN-PT ceramics and single crystals were usuallyused in the ultrasound transducers and sensors due to their fine piezoelectric properties.As the luminescence treasury house,rare-earth elements were often doped into host lattice as sensitizers and activators to achieve multifunctional application.Moreover,rare-earth doped PMN-PT can achieve the electro-mechano-optical conversions.So the research on this topic has become the current issue in the area of functional material.The research of this thesis mainly includes the synthesis of Yb³⁺ and Ho³⁺ doped PMN-PT ceramics by solid phase sintering method..The percentage of PT was fixed at 33%,which was at the morphotropic phase boundary?MPB?.By controling the preparation process,we repeatably obtained the densified PMN-PT multifunctional ceramics,which have good ferroelectric and piezoelectric properties.Moreover,this thesis investigated the upconversion photoluminescence properties of the as-synthesized samples.The optimal luminescence concentration was observed.The power dependent upconversion photoluminescence properties were also studied,and the possible mechanism of the upconversion luminescence was proposed.The process of energy transition was analyzed by the energy level diagram of rare earth.The temperature dependent upconversion was investigated by measuring the photoluminescence spectra.The result was fitted and the temperature sensitivity was calculated.By analyzing the fluorescence intensity ratio of green and red emission,the response of upconversion process to temperature variation was discussed.Furthermore,we studied the electric properties and investigated the polarization effect on the upconversion in situ.The P-E hysteresis loops were measured and the pyroelectric coefficients were calculated.The Pyroelectric coefficients as a function of temperature were investigated.The results show the phase transition feature of PMN-PT ceramics.The relaxor dielectric diffusion character was observed through the temperature dependent permittivity.And the difference of upconversion spectra between the poled and thermal depoled samples illustrated tuning effect of the upconversion luminescence by ferroelectric polarization.This is a possible way to achieve the electro-mechano-optical integration and tuning the upconversion photoluminescence by electrical field.These research results experimentally making the ferroelectric material getting the upconvertion luminescence properties.These research are helpful for the multidiscipline research.These research work based on upconversion will provide the reference for the non-contact temperature sensor and infra sensor applications.The research related to ferroelectric domains has promoted the understanding of the microcosmic level of the ferroelectric piezoelectric performance of ferroelectric ceramics to a certain extent,which is helpful to improve the origin of the electrical properties of ferroelectric piezoelectric materials.