Although the antimony(Sb)has been widely used to modify potassium sodium niobate(KNN)ceramics for tailoring the phase structure and performance,the role of Sb still remains insufficiently understood,consequently hinde...Although the antimony(Sb)has been widely used to modify potassium sodium niobate(KNN)ceramics for tailoring the phase structure and performance,the role of Sb still remains insufficiently understood,consequently hindering the understanding of the physical origin of high-performance KNN-based ceramics.Here,we combine the experiments and first-principles calculations to deeply reveal the effects of Sb on KNN ceramics.Our results reveal a re-entrant-like relaxation behavior near the rhombohedralorthorhombic(R-O)phase transition at the low content of Sb,which transforms into a canonical one at higher content of Sb.First-principles calculations show a significantly decreased difference in the bond length of six B-O bonds of Nb O6 octahedral in Sb-modified KNN ceramics compared to pristine KNN ceramics,responsible for the low-temperature re-entrant-like dielectric relaxation.Furthermore,the addition of Sb would soften the B-O repulsion and gradually break the long-range ferroelectric ordering,resulting in the occurrence of nanoscale domains and enhanced local heterogeneity.Finally,we find that the optimized piezoelectric properties are the trade-off between the long-range ferroelectric ordering and the local heterogeneity.Therefore,this work not only deeply reveals the effects of Sb on KNN ceramics from multi-scale perspectives but also helps the future composition design for achieving high piezoelectricity.展开更多
High-performance lead-free piezoelectric ceramics with knockdown strain hysteresis are key components of high-precision actuators.However,high strain hysteresis in BaTiO_(3)-based ceramics results in stability degrada...High-performance lead-free piezoelectric ceramics with knockdown strain hysteresis are key components of high-precision actuators.However,high strain hysteresis in BaTiO_(3)-based ceramics results in stability degradation,lifespan reduction,and inferior positioning accuracy.Therefore,in this work,a(1-x)Ba(Sn_(0.11)Ti_(0.89))O_(3)-xSrTiO_(3)-0.6 wt%MnO_(2)(BST-xST)composition is elaborately designed to reduce strain hysteresis.Ultralow strain hysteresis(4.8%)is achieved by adjusting the phase structure and domain configuration.The transmission electron microscopy(TEM)results revealed that the composition consists of a rhombohedral-orthorhombic-tetragonal-cubic(R-O-T-C)four-phase,nanodomains,and active polar nanoregions(PNRs).Moreover,the piezoresponse force microscopy(PFM)results revealed that these active PNRs can respond quickly to applied electric field stimuli.These findings provide a feasible path to prepare piezoelectric compositions with ultralow strain hysteresis.展开更多
Piezoelectric energy harvesters(PEHs)fabricated using piezoceramics could convert directly the mechanical vibration energy in the environment into electrical energy.The high piezoelectric charge coefficient(d_(33))and...Piezoelectric energy harvesters(PEHs)fabricated using piezoceramics could convert directly the mechanical vibration energy in the environment into electrical energy.The high piezoelectric charge coefficient(d_(33))and large piezoelectric voltage coefficient(g_(33))are key factors for the high-performance PEHs.However,high d_(33)and large g_(33)are difficult to simultaneously achieve with respect to g_(33)=d_(33)/(e_(0)e_(r))and d_(33)=2Qe_(0)e_(r)P_(r).Herein,the energy harvesting performance is optimized by tailoring the CaZrO_(3)content in(0.964−x)(K_(0.52)Na_(0.48))(Nb_(0.96)Sb_(0.04))O_(3)-0.036(Bi_(0.5)Na_(0.5))ZrO_(3)-xCaZrO_(3)ceramics.First,the doping CaZrO_(3)could enhance the dielectric relaxation due to the compositional fluctuation and structural disordering,and thus reduce the domain size to~30 nm for x=0.006 sample.The nanodomains switch easily to external electric field,resulting in large polarization.Second,the rhombohedral-orthorhombic-tetragonal phases coexist in x=0.006 sample,which reduces the polarization anisotropy and thus improves the piezoelectric properties.The multiphase coexistence structures and miniaturized domains contribute to the excellent piezoelectric properties of d_(33)(354 pC/N).Furthermore,the dielectric relative permittivity(ε_(r))reduces monotonously as the CaZrO_(3)content increases due to the relatively low ion polarizability of Ca^(2+)and Zr^(4+).As a result,the optimized energy conversion coefficient(d_(33)×g_(33),5508×10^(−15)m^(2)/N)is achieved for x=0.006 sample.Most importantly,the assembled PEH with the optimal specimen shows the excellent output power(~48 mW)and lights up 45 red commercial light-emitting diodes(LEDs).This work demonstrates that tailoring ferroelectric/relaxor behavior in(K,Na)NbO_(3)-based piezoelectric ceramics could effectively enhance the electrical output of PEHs.展开更多
基金the National Natural Science Foundation of China(Nos.52061130216 and 52002252)the Sichuan Science and Technology Program(No.2020YJ0070)+3 种基金the Central Funds Guiding the Local Science and Technology Development of Sichuan Province(2021ZYD0022)the Fundamental Research Funds for the Central Universities(YJ2021154)the R&D Projects in Key Fields of Guangdong Province,China(No.2020B0109380001)the support from King Abdullah University of Science and Technology(KAUST)。
文摘Although the antimony(Sb)has been widely used to modify potassium sodium niobate(KNN)ceramics for tailoring the phase structure and performance,the role of Sb still remains insufficiently understood,consequently hindering the understanding of the physical origin of high-performance KNN-based ceramics.Here,we combine the experiments and first-principles calculations to deeply reveal the effects of Sb on KNN ceramics.Our results reveal a re-entrant-like relaxation behavior near the rhombohedralorthorhombic(R-O)phase transition at the low content of Sb,which transforms into a canonical one at higher content of Sb.First-principles calculations show a significantly decreased difference in the bond length of six B-O bonds of Nb O6 octahedral in Sb-modified KNN ceramics compared to pristine KNN ceramics,responsible for the low-temperature re-entrant-like dielectric relaxation.Furthermore,the addition of Sb would soften the B-O repulsion and gradually break the long-range ferroelectric ordering,resulting in the occurrence of nanoscale domains and enhanced local heterogeneity.Finally,we find that the optimized piezoelectric properties are the trade-off between the long-range ferroelectric ordering and the local heterogeneity.Therefore,this work not only deeply reveals the effects of Sb on KNN ceramics from multi-scale perspectives but also helps the future composition design for achieving high piezoelectricity.
基金fundings from the National Natural Science Foundation of China(Nos.12364015 and 52176072)the National Key R&D Program of China(No.2022YFF0706500)+4 种基金the Guizhou University Natural Science Special(special post)Research Fund(No.(2023)17)the Guizhou Engineering Research Center for Smart Services(No.2203-520102-04-04-298868)the Construction of Science and Technology Platform of Guiyang(No.[2023]7-3)the Industry and Education Combination Innovation Platform of Intelligent Manufacturing and Graduate Joint Training Base at Guizhou University(No.2020-520000-83-01-324061)the Five-year Action Plan for Shccig-Qinling Program and Key Project of Hubei Province Key Research and Development Plan(No.2021BCA140).
文摘High-performance lead-free piezoelectric ceramics with knockdown strain hysteresis are key components of high-precision actuators.However,high strain hysteresis in BaTiO_(3)-based ceramics results in stability degradation,lifespan reduction,and inferior positioning accuracy.Therefore,in this work,a(1-x)Ba(Sn_(0.11)Ti_(0.89))O_(3)-xSrTiO_(3)-0.6 wt%MnO_(2)(BST-xST)composition is elaborately designed to reduce strain hysteresis.Ultralow strain hysteresis(4.8%)is achieved by adjusting the phase structure and domain configuration.The transmission electron microscopy(TEM)results revealed that the composition consists of a rhombohedral-orthorhombic-tetragonal-cubic(R-O-T-C)four-phase,nanodomains,and active polar nanoregions(PNRs).Moreover,the piezoresponse force microscopy(PFM)results revealed that these active PNRs can respond quickly to applied electric field stimuli.These findings provide a feasible path to prepare piezoelectric compositions with ultralow strain hysteresis.
基金This work was supported by the National Natural Science Foundation of China(Nos.52072150 and 51972146)the China Association for Science and Technology(Young Elite Scientists Sponsorship Program)the State Key Laboratory of New Ceramics and Fine Processing Tsinghua University(No.KF202002).
文摘Piezoelectric energy harvesters(PEHs)fabricated using piezoceramics could convert directly the mechanical vibration energy in the environment into electrical energy.The high piezoelectric charge coefficient(d_(33))and large piezoelectric voltage coefficient(g_(33))are key factors for the high-performance PEHs.However,high d_(33)and large g_(33)are difficult to simultaneously achieve with respect to g_(33)=d_(33)/(e_(0)e_(r))and d_(33)=2Qe_(0)e_(r)P_(r).Herein,the energy harvesting performance is optimized by tailoring the CaZrO_(3)content in(0.964−x)(K_(0.52)Na_(0.48))(Nb_(0.96)Sb_(0.04))O_(3)-0.036(Bi_(0.5)Na_(0.5))ZrO_(3)-xCaZrO_(3)ceramics.First,the doping CaZrO_(3)could enhance the dielectric relaxation due to the compositional fluctuation and structural disordering,and thus reduce the domain size to~30 nm for x=0.006 sample.The nanodomains switch easily to external electric field,resulting in large polarization.Second,the rhombohedral-orthorhombic-tetragonal phases coexist in x=0.006 sample,which reduces the polarization anisotropy and thus improves the piezoelectric properties.The multiphase coexistence structures and miniaturized domains contribute to the excellent piezoelectric properties of d_(33)(354 pC/N).Furthermore,the dielectric relative permittivity(ε_(r))reduces monotonously as the CaZrO_(3)content increases due to the relatively low ion polarizability of Ca^(2+)and Zr^(4+).As a result,the optimized energy conversion coefficient(d_(33)×g_(33),5508×10^(−15)m^(2)/N)is achieved for x=0.006 sample.Most importantly,the assembled PEH with the optimal specimen shows the excellent output power(~48 mW)and lights up 45 red commercial light-emitting diodes(LEDs).This work demonstrates that tailoring ferroelectric/relaxor behavior in(K,Na)NbO_(3)-based piezoelectric ceramics could effectively enhance the electrical output of PEHs.
