A novel Na_(1−x)K_(x)TaO_(3)(x=0,0.025,0.05,0.075,0.1,and 0.15)ceramic with high permittivity and high positive temperature coefficient was synthesized via the conventional solid-state method.All samples were determin...A novel Na_(1−x)K_(x)TaO_(3)(x=0,0.025,0.05,0.075,0.1,and 0.15)ceramic with high permittivity and high positive temperature coefficient was synthesized via the conventional solid-state method.All samples were determined to be pure phase orthorhombic NaTaO3 structure of space group Pmcn,and larger grain and lower porosity were observed after adding an appropriate amount of K+ions.The Q×f value is majored by the packing fraction and grain size,while the value ofτf is influenced by Ta–O bond valence.The Na_(0.95)K_(0.05)TaO_(3) ceramic possesses excellent dielectric properties ofεr=164.29,Q×f=9091 GHz(f=3.15 GHz),tanδ=3.46×10^(–4),τf=+809.52 ppm/℃,sintered at 1550℃.Compared with NaTaO_(3) ceramics,the Na_(1−x)K_(x)TaO_(3)ceramics prepared in this study demonstrate higher dielectric constants and higher positive temperature coefficients,which are promising for device miniaturization andτf compensators.展开更多
A library of ceramic compounds based on the lead-free(K_(x)Na_(1-x))1-yLiy(Nb1-zTaz)O_(3)solid solution has been synthesized and characterized using high-throughput experimentation(HTE)method.The phase space previousl...A library of ceramic compounds based on the lead-free(K_(x)Na_(1-x))1-yLiy(Nb1-zTaz)O_(3)solid solution has been synthesized and characterized using high-throughput experimentation(HTE)method.The phase space previously reported by Saito and Takao has been expanded to{{x,0.1,1.0},{y,0,0.1},{z,0,0.2}},and new phase boundaries are observed.The relative density values show that with the appropriate sintering temperature,~92%of the theoretical density can be reached.The relative permittivity values show that with increasing amount of K+and Ta5+,the dielectric constant values increase.The effect of density on the dielectric constant values is however minimal.Resistivity values ranging from 109 to 1013Ω·cm are obtained for the samples.The piezoelectric charge coefficient values for selected compositions show that higher values are obtained close to the phase boundaries rather than away from them.The properties for the ceramic library using the HTE method are generally 15%-20%less than from the conventional method.This method is therefore more suited for screening of sample compositions than for producing samples with high piezoelectric properties.展开更多
AgNbO_(3) is an antiferroelectric (AFE) material with double hysteresis loop. Both the antiferroelectricityand ferroelectricity can be enhanced by doping. Herein, the ferroelectricity of AgNbO_(3) ceramics wasenhanced...AgNbO_(3) is an antiferroelectric (AFE) material with double hysteresis loop. Both the antiferroelectricityand ferroelectricity can be enhanced by doping. Herein, the ferroelectricity of AgNbO_(3) ceramics wasenhanced via K-doping and the phase diagram of the (Ag_(1-x)K_(x))NbO_(3) ceramics was upgraded. In details,(Ag_(1-x)K_(x))NbO_(3) ceramics are ferrielectric (FIE) M1 phase as x=5.00-5.50 mol% and ferroelectric (FE) Ophase as x=5.75-6.00 mol% before poling, and FE O phase as x=5.00-6.00 mol% after poling at roomtemperature. With increasing temperature, (Ag_(1-x)K_(x))NbO_(3) ceramics show the phase evolutions from FIEM1, AFE M2 to paraelectric (PE) T phase at x=5.00-5.50 mol% and from FE O, FE T to PE T phase at x=5.75-6.00 mol% before poling, and from FE O, FE T to PE T phase at x=5.00-6.00 mol% after poling.High d33 values of 180 pC/N and 285 pC/N are obtained at the FE O-FE T and FE T-PE T phase boundaries.This work sheds light on a novel and promising lead-free piezoelectric system.展开更多
基金supported by the National Key R&D Program(No.2022YFB2807405)the Natural Science Foundation of Sichuan Province(No.2022NSFSC1959)the Open Foundation of National Engineering Research Center of Electromagnetic Radiation Control Materials(No.ZYGX2020K009-1).
文摘A novel Na_(1−x)K_(x)TaO_(3)(x=0,0.025,0.05,0.075,0.1,and 0.15)ceramic with high permittivity and high positive temperature coefficient was synthesized via the conventional solid-state method.All samples were determined to be pure phase orthorhombic NaTaO3 structure of space group Pmcn,and larger grain and lower porosity were observed after adding an appropriate amount of K+ions.The Q×f value is majored by the packing fraction and grain size,while the value ofτf is influenced by Ta–O bond valence.The Na_(0.95)K_(0.05)TaO_(3) ceramic possesses excellent dielectric properties ofεr=164.29,Q×f=9091 GHz(f=3.15 GHz),tanδ=3.46×10^(–4),τf=+809.52 ppm/℃,sintered at 1550℃.Compared with NaTaO_(3) ceramics,the Na_(1−x)K_(x)TaO_(3)ceramics prepared in this study demonstrate higher dielectric constants and higher positive temperature coefficients,which are promising for device miniaturization andτf compensators.
基金The research leading to these results has received financial support from the Deutsche Forschungs Gemeinschaft(DFG)under Grant No.SCHN 372/16:1-2.
文摘A library of ceramic compounds based on the lead-free(K_(x)Na_(1-x))1-yLiy(Nb1-zTaz)O_(3)solid solution has been synthesized and characterized using high-throughput experimentation(HTE)method.The phase space previously reported by Saito and Takao has been expanded to{{x,0.1,1.0},{y,0,0.1},{z,0,0.2}},and new phase boundaries are observed.The relative density values show that with the appropriate sintering temperature,~92%of the theoretical density can be reached.The relative permittivity values show that with increasing amount of K+and Ta5+,the dielectric constant values increase.The effect of density on the dielectric constant values is however minimal.Resistivity values ranging from 109 to 1013Ω·cm are obtained for the samples.The piezoelectric charge coefficient values for selected compositions show that higher values are obtained close to the phase boundaries rather than away from them.The properties for the ceramic library using the HTE method are generally 15%-20%less than from the conventional method.This method is therefore more suited for screening of sample compositions than for producing samples with high piezoelectric properties.
基金This work was supported by the National Natural Science Foun-dation of China(No.51802068 and No.52073144)the Natural Sci-ence Foundation of Hebei Province,China(No.E2021201044)+4 种基金the Advanced Talents Incubation Program of the Hebei University,China(No.801260201180)the Natural Science Foundation of Jiangsu Province,China(No.BK20201301)the State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(No.KF202005 and No.KF202114)China Postdoctoral Science Foun-dation(No.2021M692491)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110251).
文摘AgNbO_(3) is an antiferroelectric (AFE) material with double hysteresis loop. Both the antiferroelectricityand ferroelectricity can be enhanced by doping. Herein, the ferroelectricity of AgNbO_(3) ceramics wasenhanced via K-doping and the phase diagram of the (Ag_(1-x)K_(x))NbO_(3) ceramics was upgraded. In details,(Ag_(1-x)K_(x))NbO_(3) ceramics are ferrielectric (FIE) M1 phase as x=5.00-5.50 mol% and ferroelectric (FE) Ophase as x=5.75-6.00 mol% before poling, and FE O phase as x=5.00-6.00 mol% after poling at roomtemperature. With increasing temperature, (Ag_(1-x)K_(x))NbO_(3) ceramics show the phase evolutions from FIEM1, AFE M2 to paraelectric (PE) T phase at x=5.00-5.50 mol% and from FE O, FE T to PE T phase at x=5.75-6.00 mol% before poling, and from FE O, FE T to PE T phase at x=5.00-6.00 mol% after poling.High d33 values of 180 pC/N and 285 pC/N are obtained at the FE O-FE T and FE T-PE T phase boundaries.This work sheds light on a novel and promising lead-free piezoelectric system.
