Dielectric And Optical Properties Of Lead-Free Piezoelectric Materials Doped With Rare-Earth Europium

The lead-free piezoelectric ceramic materials have attracted the attention of researchers due to its environmental harmlessness.The dielectric and optical properties of lead-free piezoelectric ceramic materials can be improved by dopping the rare-earth ions.In this paper,three groups of lead-free ceramic materials doped with europium were prepared by solid phase reaction.They are europium doped calcium titanate,silver niobate and sodium potassium niobate respectively.In this paper,the dielectric and optical properties of three groups were tested and analyzed,and the relationship of the doping concentrations and their properties was obtained.（1）Based on the preparation of high-quality samples,the structural characteristics of the samples was detected by X-ray diffractometer.The dielectric property of the sample was tested by LCR tester.The light absorption and reflection ability of samples was detected by Ultraviolet-visible photometer.The photoluminescence characteristics of samples were tested by fluorescence spectrometer.It is expected that the dielectric properties of the europium doped samples will be improved.The relative dielectric constant increases and the dielectric loss decreases.The absorption and reflection of light were enhanced.After this research,the lead-free piezoelectric ceramics can be better used in daily life instead of lead-containing materials,such as sensors and monitors.（2）In the third chapter,the Eu³⁺doped lead-free piezoelectric ceramic Ca Ti O₃containing Sn is studied,and the Ca_1-xEu_xTi_0.995Sn_0.005O₃（x=0,1%,2%,3%）system was synthesized by were prepared by solid phase method.The structure and dielectric properties of the material were characterized by X-ray diffraction and LCR tester,and their optical properties were characterized by Uv-visible photometer and fluorescence spectrometer.The results show that the structure of Ca_1-xEu_xTi_0.995Sn_0.005O₃is orthogonal.The relative dielectric constant increases with the increase of Eu³⁺concentration.The absorption spectrum has a strong absorbance in the ultraviolet region,and with the increase of doping concentration,the intensity of absorbance and reflectance increases gradually.The dielectric and luminescence properties of the material are effectively improved by doping of Eu³⁺.（3）In the fourth chapter,the rare-earth Eu³⁺doped lead-free piezoelectric ceramic material Ag Nb O₃was studied.The silver niobate based piezoelectric material was successfully prepared by the solid phase reaction method.That means that the solid phase reaction method can be used to preparation the Ag Nb O₃based piezoelectric material.The physical,ferroelectric,dielectric and piezoelectric properties of Ag Nb O₃doped with Eu³⁺were also measured.The XRD shows that there is not obvious impurity peaks of the four samples.This indicate that rare earth europium had been successfully mixed with Ag Nb O₃.It can be found that the remanent polarization and the coerce field of the sample increased with the doped Eu³⁺,and the maximum values at 0.5%mol.In addition,the visible-ultraviolet absorption also increased with the doped Eu³⁺.（4）In the fifth chapter,Eu³⁺doped(Na_0.5K_0.5)Nb O₃lead-free piezoelectric ceramics was studied.Firstly,the ceramic samples doped with KNN:Eu³⁺were successfully prepared by the traditional solid phase reaction method.Then the doping effects of KNN ceramic samples with Eu³⁺at different doping concentrations were investigated.The results show that the concentration of the doped europium is an important factor affecting the luminescence performance of the lead-free piezoelectric ceramic materials.The best dielectric property of sample was obtained at the the doping concentration is 0.5%with Pre-sintering for 3 hours at 800℃and annealing at 1000℃.With the increase of the doping amount of Eu³⁺,the piezoelectric constants of the ceramic samples also increase.In terms of ultraviolet absorption,the absorption intensity reaches the maximum withn the doping concentration of 0.5%.