Potassium–sodium niobate(K,Na)NbO3/(KNN)lead-free ceramics have drawn vast amount of attention as one of the effective alternatives to lead-based ones.In recent years,the author’s group concentrated their work on KN...Potassium–sodium niobate(K,Na)NbO3/(KNN)lead-free ceramics have drawn vast amount of attention as one of the effective alternatives to lead-based ones.In recent years,the author’s group concentrated their work on KNN-based ceramics.This paper reviews the main obtained results in authors’laboratory on how to enhance the piezoelectric properties of KNN-based ceramics,including the ions or compounds substitution,the constructing and types of phase boundaries near room temperature,the investigation of other tools(sintering aids,synthesis technique,poling conditions)on properties.All the published papers up to now show the developing higher performance with maintaining high Curie temperature of KNN-based ceramics which has great potential for the future and is the key to success for the field.展开更多
The rapidly advancing energy storage performance of dielectric ceramics capacitors has garnered significant interest for applications in fast charge/discharge and high-power electronic techniques.Exploring the excepti...The rapidly advancing energy storage performance of dielectric ceramics capacitors has garnered significant interest for applications in fast charge/discharge and high-power electronic techniques.Exploring the exceptional electrical properties in harsh environments can further promote their practical applications.Defect carriers can be excited under luminance irradiation,thereby leading to degradation of energy storage performance.Herein,a synergic optimization strategy is proposed to enhance energy storage properties and luminance resistance of(K_(0.5)Na_(0.5))NbO_(3)-base(KNN)ceramics.First,the introduction of Bi(Zn0.5Ti0.5)O_(3) solid solution and La3+ions disrupts the long-range polar orders and enhances super paraelectric relaxation characteristics.Additionally,doping La3+ions can increase the band gap and reduce oxygen vacancy concentration,resulting in excellent luminance resistance.Finally,the viscous polymer process is employed to suppress the grain growth and promote chemical homogeneity.As a result,ultrahigh recoverable energy storage density(Wrec)of 8.11 J/cm3 and high efficiency(η)of 80.98%are achieved under an electric field of 568 kV/cm.Moreover,the variations in Wrec andηare only 12.45%and 1.75%,respectively,under 500 W xenon lamp irradiation compared to the performance under a dark environment.These findings hold great potential in facilitating the practical application of dielectric ceramic capacitors in luminance irradiation environments.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
There has been a surge of research interest in the promising lead-free potassium-sodium niobate(KNN)-based ceramics,applications of which could be significantly promoted by improving thermal stability of piezoelectric...There has been a surge of research interest in the promising lead-free potassium-sodium niobate(KNN)-based ceramics,applications of which could be significantly promoted by improving thermal stability of piezoelectricity.Besides,endowing the KNN-based ceramics with photoluminescence property by rare-earth-ion doping can make them more completive lead-free counterparts in potential applications such as novel multifunctional sensing devices.Herein,a novel KNN-based ceramic material doped with Eu was elaborately designed to simultaneously obtain enhanced temperaturestable piezoelectricity and good luminescence property.By the introduction of diffused phase transition and the modulation of unit cell distortion,a large piezoelectric strain coefficient(d^(*)_(33))with a small variation(590±59 pm/V)over a wide temperature range(from room temperature to 110℃)was realized.The optimal composition also exhibited a considerable piezoelectric coefficient(d_(33))with small fluctuation(330±33 pC/N)from 20 to 80℃.In addition to the enhanced temperature-stable piezoelectricity,the luminescence of these ceramics was slightly enhanced with the elevation of BaZrO_(3)(BZ)doping contents,which could be attributed to the increased compositional disorder and the decreased unit cell distortion of the matrix material.Moreover,an optical characteristic was more prominent at ultra-low temperatures.This work unprecedentedly provides a novel paradigm for the design of multifunctional KNN-based ceramics with enhanced temperature-stable piezoelectricity and good luminescence property,revealing the great potential of the rare-earth-element-doped KNN material for future applications in the novel multifunctional devices.展开更多
(1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3(KNN–x BLZ, x = 0–0.06) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method, and their phase structures and electric pr...(1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3(KNN–x BLZ, x = 0–0.06) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method, and their phase structures and electric properties as well as T_C were systematically investigated. The orthorhombic–tetragonal(O–T) two phases were detected in all(1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3 ceramics at 0.01 ≤ x ≤ 0.05. Due to the appropriate ratio between O phase and T phase(CO/C T= 45/55), high piezoelectric properties of d 33= 239 pC/N, k_p= 34%, and P_r = 25.23 μC/cm^2 were obtained at x = 0.04. Moreover, a high T_C = 348 ℃ was also achieved in KNN–x BLZ ceramic at x = 0.04. These results indicate that (1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3 system is a promising candidate for high-temperature piezoelectric devices.展开更多
The present article aims to give a brief overview about the advantages of the hydrothermal crystallization method for the synthesis of advanced ceramics.Emphasis is given,not only on the conventional hydrothermal crys...The present article aims to give a brief overview about the advantages of the hydrothermal crystallization method for the synthesis of advanced ceramics.Emphasis is given,not only on the conventional hydrothermal crystallization,but also on some of its variants;such as ultrasound-assisted,electrochemical-assisted,microwave-assisted and surfactant-assisted hydrothermal methods which open up new opportunities for the synthesis of ceramic materials with novel properties demanded for advanced applications.In the current work the synthesis of barium titanate(BaTiO3),lithium metasilicate(Li2SiO3)and sodium-potassium niobate(Na,K)NbO3 powders are reported as cases of study.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.51332003).
文摘Potassium–sodium niobate(K,Na)NbO3/(KNN)lead-free ceramics have drawn vast amount of attention as one of the effective alternatives to lead-based ones.In recent years,the author’s group concentrated their work on KNN-based ceramics.This paper reviews the main obtained results in authors’laboratory on how to enhance the piezoelectric properties of KNN-based ceramics,including the ions or compounds substitution,the constructing and types of phase boundaries near room temperature,the investigation of other tools(sintering aids,synthesis technique,poling conditions)on properties.All the published papers up to now show the developing higher performance with maintaining high Curie temperature of KNN-based ceramics which has great potential for the future and is the key to success for the field.
基金supported by the National Natural Science Foundation of China(Grant Nos.52072150 and 51972146)Shandong Province Key Fundamental Research Program(Grant No.ZR2022ZD39).
文摘The rapidly advancing energy storage performance of dielectric ceramics capacitors has garnered significant interest for applications in fast charge/discharge and high-power electronic techniques.Exploring the exceptional electrical properties in harsh environments can further promote their practical applications.Defect carriers can be excited under luminance irradiation,thereby leading to degradation of energy storage performance.Herein,a synergic optimization strategy is proposed to enhance energy storage properties and luminance resistance of(K_(0.5)Na_(0.5))NbO_(3)-base(KNN)ceramics.First,the introduction of Bi(Zn0.5Ti0.5)O_(3) solid solution and La3+ions disrupts the long-range polar orders and enhances super paraelectric relaxation characteristics.Additionally,doping La3+ions can increase the band gap and reduce oxygen vacancy concentration,resulting in excellent luminance resistance.Finally,the viscous polymer process is employed to suppress the grain growth and promote chemical homogeneity.As a result,ultrahigh recoverable energy storage density(Wrec)of 8.11 J/cm3 and high efficiency(η)of 80.98%are achieved under an electric field of 568 kV/cm.Moreover,the variations in Wrec andηare only 12.45%and 1.75%,respectively,under 500 W xenon lamp irradiation compared to the performance under a dark environment.These findings hold great potential in facilitating the practical application of dielectric ceramic capacitors in luminance irradiation environments.
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.
基金supported by the National Natural Science Foundation of China (Nos.52002051 and 62074025)the Fundamental Research Funds for the Central Universities (No.ZYGX2020J009)the Applied Basic Research Program of Sichuan Province (No.2021JDGD0026).
文摘There has been a surge of research interest in the promising lead-free potassium-sodium niobate(KNN)-based ceramics,applications of which could be significantly promoted by improving thermal stability of piezoelectricity.Besides,endowing the KNN-based ceramics with photoluminescence property by rare-earth-ion doping can make them more completive lead-free counterparts in potential applications such as novel multifunctional sensing devices.Herein,a novel KNN-based ceramic material doped with Eu was elaborately designed to simultaneously obtain enhanced temperaturestable piezoelectricity and good luminescence property.By the introduction of diffused phase transition and the modulation of unit cell distortion,a large piezoelectric strain coefficient(d^(*)_(33))with a small variation(590±59 pm/V)over a wide temperature range(from room temperature to 110℃)was realized.The optimal composition also exhibited a considerable piezoelectric coefficient(d_(33))with small fluctuation(330±33 pC/N)from 20 to 80℃.In addition to the enhanced temperature-stable piezoelectricity,the luminescence of these ceramics was slightly enhanced with the elevation of BaZrO_(3)(BZ)doping contents,which could be attributed to the increased compositional disorder and the decreased unit cell distortion of the matrix material.Moreover,an optical characteristic was more prominent at ultra-low temperatures.This work unprecedentedly provides a novel paradigm for the design of multifunctional KNN-based ceramics with enhanced temperature-stable piezoelectricity and good luminescence property,revealing the great potential of the rare-earth-element-doped KNN material for future applications in the novel multifunctional devices.
基金supported by Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20130006110006)National Natural Science Foundation of China(Grant Nos.51272023 and 51472026)
文摘(1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3(KNN–x BLZ, x = 0–0.06) lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method, and their phase structures and electric properties as well as T_C were systematically investigated. The orthorhombic–tetragonal(O–T) two phases were detected in all(1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3 ceramics at 0.01 ≤ x ≤ 0.05. Due to the appropriate ratio between O phase and T phase(CO/C T= 45/55), high piezoelectric properties of d 33= 239 pC/N, k_p= 34%, and P_r = 25.23 μC/cm^2 were obtained at x = 0.04. Moreover, a high T_C = 348 ℃ was also achieved in KNN–x BLZ ceramic at x = 0.04. These results indicate that (1–x)K_(0.48)Na_(0.56)NbO_3–xBi_(0.5)Li_(0.5)ZrO_3 system is a promising candidate for high-temperature piezoelectric devices.
基金The authors thank to SIP-IPN and SNI-CONACYT México for the financial support.
文摘The present article aims to give a brief overview about the advantages of the hydrothermal crystallization method for the synthesis of advanced ceramics.Emphasis is given,not only on the conventional hydrothermal crystallization,but also on some of its variants;such as ultrasound-assisted,electrochemical-assisted,microwave-assisted and surfactant-assisted hydrothermal methods which open up new opportunities for the synthesis of ceramic materials with novel properties demanded for advanced applications.In the current work the synthesis of barium titanate(BaTiO3),lithium metasilicate(Li2SiO3)and sodium-potassium niobate(Na,K)NbO3 powders are reported as cases of study.
