Optic And Electric Properties Of Eu Doped BT Based Ceramics With Fluorescent Monitering

Rare-earth-doped lead-free piezoelectric ferroelectrics are a new class of optical,electric and mechanical integrated multifunctional materials.Due to the unique properties of rare earth ions and ferroelectric materials,this new material s have great potential in sensing,detection,and information transfer.Ba Ti O₃?BT?-based ferroelectric ceramics are one of the most promising lead-free systems.The rare earth doping will regulate the structure and properties of BT-based ceramics.To obtain excellent photoelectric properties,various parameters need to be adjusted.In this paper,Eu³⁺doped Ba_0.7Ca_0.3Ti O₃?BCT30?and Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃?BCZT?ceramics were prepared by the traditional high-temperature solid-state method.By adjusting the sintering temperature and doping concentration,the influence of the parameters on the surface morphology,crystal structure and electrical properties of the ceramics was studied and the causes were analyzed.The results show that the optimum sintering temperature of BCT30 ceramic is 1340°C.The substitution of 3%concentration of Eu³⁺at the A position reduces the phase transition point of BCT30 ceramic to 103°C,slightly improves the piezoelectric coefficient d₃₃,but decrease the residual polarization P_r and The coercive field E_c.according to the J-E curve,the polarization intensity mainly originates from the domain inversion in the low voltage range.The best sintering temperature of BCZT ceramics is 1325°C.The doping of Eu³⁺slightly reduces the rhombohedral-tetragonal?R-T?and ferroelectric-paraelectric?T-C?phase transition temperature.Therefore,the piezoelectric coefficient d₃₃is significantly reduced,and the residual polarization Pr and the coercive field Ec are also decreased due to "Soft blend" effect.In short,Eu³⁺doping reduces the difficulty of polarization,but has an influence on polarization intensity and piezoelectricity,and drives the phase transition point to a low temperature region.The ceramic sample obtained under the above conditions was studied for its luminescence characteristics.The phase transition can be observed in the absolute intensity of ⁵D₀-⁷F₂ transition peak of BCT30:5Eu ceramic changing with temperature,but it is not obvious.However,,the ferroelectric-paraelectric phase transition peaks of the materials can be clearly found in the variation of⁵D₀-⁷F₂/⁵D₀-⁷F₁ along with temperature.The Curie temperature T_c=70°C.According to the auxiliary analysis of the material's dielectric dispersion and temperature transition,the peak is derived from the disorder of the local str ucture of crystal.In the BCZT:Eu ceramics,the phase transition peak caused by the structural disorder can also be observed in the intensity ratio curve along with temperature,T_c=60°C.However,the R-T phase transition peak is concealed,and the information needs to obtained from the ⁵D₀-⁷F₂ absolute intensity changing with temperature curve,T_R-T=-10°C.The I-E curves of the two types ceramics were analyzed.The law was firstly increased and then stabilized,and the increment continuously decreased to zero.The maximum light intensity was increased by 14.5%.Apart from the electric field-induced phase transformation and the ion-shift polarization,and the domain reversal is also one of the important factors for reducing the symmetry and increasing the light intensity.This work has a certain guiding significance for improving the performance of rare-earth-doped piezoelectric system and extending its application range.