Research On The Energy-Storage Characteristics Of Lead-Free AgNbO₃ Antiferroelectric Ceramics Controlled By A/B Sites

With the rapid development of pulse technology,high quality dielectric capacitors are needed.Due to its lower recoverable energy-storage density(W_rec=1.8 J/cm³)and large energy loss（η=30%）,which restricts silver niobate（Ag Nb O₃,abbreviated:AN）development.This paper used the traditional solid phase method,synthesizing Ag Nb O₃ceramics under oxygen atmosphere as the underlying body of the study,and using an A/B-bit mixing method to improve the energy-storage density and energy efficiency of Ag Nb O3-based ceramic.The system studied the microstructure,electrical properties and photoluminescence properties of A/B bits of Ag Nb O₃-based ceramics.It provides theoretical and data references for the study of subsequent dielectric energy-storage devices,here are the main contents of this article:（1）The Ag⁺position in Ag Nb O₃-based ceramics is replaced by Er³⁺ions with smaller radius,resulting in a uniform and stable perovskite structure,accompanied by a reduction in grain size.The doped of Er³⁺can make the ceramic crystals fine,improve the breakdown field strength,and reduce dielectric loss.A recoverable energy-storage density of 2.6 J/cm³ and an energy efficiency of 53%was achieved in the antiferroelectric ceramic(Ag_0.94Er_0.02)Nb O₃,which is better than pure Ag Nb O₃ The phase variation temperatures T_M1-M2 and T_M2-M3 both have a tendency to move to low temperatures,indicating that the doped of moderate Er³⁺enhances antiferroelectricity to a certain extent.With the further increase of the doped of Er³⁺,the phase shift from antiferroelectric to ferroelectric received a certain limitation.Besides,the PL intensity of AN-Erx(Ag_1-3xEr_xNb O₃)based ceramics is increased rapidly when x is bigger due to the synergy between ions.（2）The results show that Er³⁺and Ta⁵⁺ions doped into the Ag Nb O₃ matrix do not change the perovskite structure of Ag Nb O₃,and the ceramic surface is dense with clear particles,and the grain size rapidly decreases.The（Ag0.94Er0.02）（Nb0.9Ta0.1）O3 ceramic energy-storage density and energy efficiency can reach 3.95 J/cm³and 66.5%,respectively,at an electric field of 270 k V/cm.Furthermore,the as-prepared AFE sample exhibited excellent thermal stability at 20-120℃（with a change of<8%）.In addition,the thinning mechanism of the hysteresis loops is illustrated by Raman.As the introduction of Ta⁵⁺improves the order of the lattice,the increase of Er³⁺luminescence groups make the distance between the emission centers of rare earth ions Er³⁺closer,thus forming a synergistic effect and rapidly enhancing the intensity of up-conversion PL.As the Er³⁺concentration increases,the E_F（antiferroelectric-ferroelectric phase field）and the E_A（ferroelectric-antiferroelectric phase field）rise;the phase temperature T_M1-M2 and T_M2-M3 tend to move toward low temperatures;and in the XPS test,the peak Ag3d and Nb3d both move to higher binding energy.These factors suggest that Ag Nb O₃-based ceramics have to a certain extent enhanced their antiferroelectric properties.（3）The AN-Eux Hfy(Ag_1-3xEu_xNb_1-4/5yHf_yO₃)ceramics doped with different concentrations of Eu³⁺and Hf⁴⁺show a uniform and stable perovskite structure.The ceramic texture is dense,with distinct particles,and the grain size shrinks rapidly.Under a super-high electric field of 320k V/cm,it can achieve a recoverable energy-storage density of 4.08 J/cm³ and an energy efficiency of 65.0%.Moreover,it exhibits excellent temperature stability of energy density,with a change of<10%in the energy storage density temperature range of 20-120℃.Due to the presence of the Hf O₂ phase,the grain size is maintained below 1.5μm.The(Ag_0.91Eu_0.03)(Nb_0.96Hf_0.05)O₃ ceramic exhibits high transparency,with an optical transmittance of 42%at 780 nm.Due to its high dielectric breakdown field strength,along with the increase of E_F and E_A,the phase transition temperatures T_M1-M2 and T_M2-M3 show a trend towards lower temperatures.Both Ag3d and Nb3d peaks shift towards higher binding energy.These factors suggest that Ag Nb O₃-based ceramics have to a certain extent enhanced their antiferroelectric properties.