The Tuning Of Ferroelectric,Energy Storage And Luminescence Properties For Lead-free Perovskite-Type Ferroelectric Ceramics By Rare-earth Doping

The methods that rare earth doped ferroelectric ceramics provide an opportunity to develop multi-functional materials.In this work,the effects of rare earth concentration on the microstructure,ferroelectric,dielectric,energy storage and photoluminescence properties of different host ferroelectric materials were systematically investigated.The main results are as follows:The x mol Sm³⁺doped Ba Ti O₃(BTO:x Sm³⁺)ceramics were prepared by solid state reaction methods.The effects of Sm³⁺concentration on the phase structure,ferroelectric,energy storage and photoluminescence properties of BTO ceramics were systematically studied.The remnant polarization P_r of BTO ceramics is reduced from15.705μC/cm²（pure BTO）to 7.132μC/cm²(BTO:1.0%Sm³⁺)with the increase of Sm³⁺concentration.The results indicate that the Sm³⁺doping can induce the transition from normal ferroelectrics to relaxor ferroelectrics.The discharge energy storage density W_d and energy storage efficiencyηare increased by 79.76%and31.13%compared with pure BTO ceramics,respectively.The Curie temperature T_C is gradually decreased with the increase of Sm³⁺concentration due to the transition from tetragonal phase to pseudo-cubic phase of BTO ceramics induced by the Sm³⁺doping at room temperature.In addition,the BTO:x Sm³⁺ceramics exhibit strong orange-red luminescence around 596 nm under the excitation of 408 nm near-ultraviolet light.The influence of co-doping of Ca²⁺and Hf⁴⁺on the microstructure and electric properties of Ba_1-xCa_xTi_1-yHf_yO₃ ceramics was investigated.And then obtained the appropriate Ca²⁺and Hf⁴⁺concentration doped Ba_0.96Ca_0.04Ti_0.85Hf_0.15O₃(BCTH:x Pr³⁺)ceramics with the best comprehensive performance.Furthermore,the effects of Pr³⁺doping on the physical properties of BCTH:x Pr³⁺ceramics were systematically studied.The crystal size is decreased with the Pr³⁺concentration,and the crystal phase gradually is changed from tetragonal phase to pseudo-cubic phase.The W_d is firstly increased and then decreased after reaching the maximum value of 0.338 J/cm³in BCTH:0.6%Pr³⁺ceramics,which is increased by 59.86%than that of pure BCTH ceramics,but theηis gradually increased.The T_C is firstly increased and then decreased with the increase of Pr³⁺concentration after reached the highest T_C of68.4°C in BCTH:0.2%Pr³⁺ceramics.Under the excitation of blue-violet light with different wavelengths,the BCTH:x Pr³⁺ceramics exhibit excellent red light emission.And the luminescence intensity strongly depends on the Pr³⁺concentration.The BCTH:0.8%Pr³⁺ceramics show the strongest luminescence intensity,which is 226%higher than that of BCTH:0.2%Pr³⁺ceramics.The effect of Er³⁺doping on the structure and properties of binary Bi_0.5Na_0.5Ti O₃-0.06Ba Ti O₃（BNT-BT）ceramics was investigated.The grain sizes of BNT-BT ceramics strongly depend on the Er³⁺concentration.The ferroelectric and dielectric properties of BNT-BT ceramics are firstly increased and then weakened due to the different substitution positions of Er³⁺with the Er³⁺doping.The W_d is gradually increased and reached maximum of 0.429 J/cm³ in BNT-BT:1.0Er³⁺ceramics.And all BNT-BT:x Er³⁺ceramics show excellent energy storage frequency stability.In addition,the transition temperature T_d,T_RE and T_m of BNT-BT ceramics strongly depends on the Er³⁺concentration.Especially,the Curie temperature T_m is gradually increased with the Er³⁺doping concentration for x<0.6%.Under the excitation of 487nm light,the BNT-BT:x Er³⁺ceramics exhibit strong green emission,and the strong emission intensity can maintain at the doping range of 0.6%-1.0%mol.