The K_xNa_((1-x))NbO_3(x=0.45, 0.46, 0.47, 0.48, 0.49, 0.50) lead-free piezoelectric ceramics was fabricated by conventional solid-state sintering method. It was found that the ratio of alkaline metal would affect the...The K_xNa_((1-x))NbO_3(x=0.45, 0.46, 0.47, 0.48, 0.49, 0.50) lead-free piezoelectric ceramics was fabricated by conventional solid-state sintering method. It was found that the ratio of alkaline metal would affect the microstructure, bulk density, and optimum sintering temperatures of ceramics. Meanwhile, the electrical properties were also influenced by modulating the K/Na ratio, exhibiting corresponding composition-dependent properties. The optimum electrical properties of K_xNa_((1-x))NbO_3 such as piezoelectric constant d_(33) = 115 pC/N, mechanical quality factor Q_m = 20, Curie temperature Tc = 365 ~oC, ε_(33)~T/ε_0= 588.1, dielectric loss tan δ = 0.024, bulk density(ρ) = 3.08 g/cm^3, remnant polarization(P_r) = 8.87 μC/cm^2 and coercive field(Ec) = 13.79 kV/cm were obtained at x = 0.46.展开更多
Graphite carbon has been successfully used for the anode materials of secondary ion batteries due to its capability of accommodating ions between graphite layers.The intercalation dynamics intrinsically determine the ...Graphite carbon has been successfully used for the anode materials of secondary ion batteries due to its capability of accommodating ions between graphite layers.The intercalation dynamics intrinsically determine the performance of the batteries.In this review,we summarize recent research progresses of structural characterizations on graphite intercalation in electrochemical devices,especially on the in‐situ study on the intercalations of Li/Na/K ions,AlCl4−and other anions,or solvents.These techniques,including X‐ray,electron microscopy,Raman,neutron scattering,nuclear magnetic resonance,and optical microscopy provide direct information of the reaction dynamics and help to understand the factors affecting the electrochemical performances of metallic ion batteries.展开更多
Although vast efforts have been given to the phase boundary engineering(PBE) of potassium sodium niobate(KNN) ceramics by using chemical dopants,the inherent issues like the K/Na ratio were not paid enough attention,h...Although vast efforts have been given to the phase boundary engineering(PBE) of potassium sodium niobate(KNN) ceramics by using chemical dopants,the inherent issues like the K/Na ratio were not paid enough attention,hindering the further understanding of physical mechanisms.Herein,we investigated the effect of the K/Na ratio on PBE-featured KNN-based ceramics.The K/Na ratio significantly influences the local A-site environment and thereby alters mesoscopic ferroelectric domains and macroscopic structure and performance.A much higher Na^(+)content results in the local stress heterogeneity,while a much higher K^(+)content brings in the local polar heterogeneity.Due to the appropriate coupling between the local stress and the polar heterogeneity,piezoelectric properties and the temperature stability of electrostrain are optimized on the Na-rich side.Therefore,beyond seeking appropriate chemical dopants,elaborately tailoring the K/Na ratio is also important for further improving the piezoelectric properties of PBE-featured KNN-based ceramics.展开更多
基金Funded by the National Natural Science Foundation of China(No.51302199)Key Natural Science Foundation of Hubei Province of China for Distinguished Yong Scholars(No.2014CFA044)+2 种基金Cultivation Plan for Science and Technology Talents of Wu Han City(No.2014072704011253)MOST Special Fund from the State Key Laboratory of Geological Process and Mineral Resources(No.MSFGPMR201204)Natural Science Foundation of Hubei Province(No.2014CFB809)
文摘The K_xNa_((1-x))NbO_3(x=0.45, 0.46, 0.47, 0.48, 0.49, 0.50) lead-free piezoelectric ceramics was fabricated by conventional solid-state sintering method. It was found that the ratio of alkaline metal would affect the microstructure, bulk density, and optimum sintering temperatures of ceramics. Meanwhile, the electrical properties were also influenced by modulating the K/Na ratio, exhibiting corresponding composition-dependent properties. The optimum electrical properties of K_xNa_((1-x))NbO_3 such as piezoelectric constant d_(33) = 115 pC/N, mechanical quality factor Q_m = 20, Curie temperature Tc = 365 ~oC, ε_(33)~T/ε_0= 588.1, dielectric loss tan δ = 0.024, bulk density(ρ) = 3.08 g/cm^3, remnant polarization(P_r) = 8.87 μC/cm^2 and coercive field(Ec) = 13.79 kV/cm were obtained at x = 0.46.
文摘Graphite carbon has been successfully used for the anode materials of secondary ion batteries due to its capability of accommodating ions between graphite layers.The intercalation dynamics intrinsically determine the performance of the batteries.In this review,we summarize recent research progresses of structural characterizations on graphite intercalation in electrochemical devices,especially on the in‐situ study on the intercalations of Li/Na/K ions,AlCl4−and other anions,or solvents.These techniques,including X‐ray,electron microscopy,Raman,neutron scattering,nuclear magnetic resonance,and optical microscopy provide direct information of the reaction dynamics and help to understand the factors affecting the electrochemical performances of metallic ion batteries.
基金supported by the National Natural Science Foundation of China (Nos.52061130216,52032007,and 52002252)the Central Funds Guiding the Local Science and Technology Development of Sichuan Province (2021ZYD0022)+2 种基金the Fundamental Research Funds for the Central Universities (YJ2021154)Chengdu International Science and Technology Cooperation Project (2021-GH03-00003-HZ)a Newton Advanced Fellowship award (NAFR1201126)。
文摘Although vast efforts have been given to the phase boundary engineering(PBE) of potassium sodium niobate(KNN) ceramics by using chemical dopants,the inherent issues like the K/Na ratio were not paid enough attention,hindering the further understanding of physical mechanisms.Herein,we investigated the effect of the K/Na ratio on PBE-featured KNN-based ceramics.The K/Na ratio significantly influences the local A-site environment and thereby alters mesoscopic ferroelectric domains and macroscopic structure and performance.A much higher Na^(+)content results in the local stress heterogeneity,while a much higher K^(+)content brings in the local polar heterogeneity.Due to the appropriate coupling between the local stress and the polar heterogeneity,piezoelectric properties and the temperature stability of electrostrain are optimized on the Na-rich side.Therefore,beyond seeking appropriate chemical dopants,elaborately tailoring the K/Na ratio is also important for further improving the piezoelectric properties of PBE-featured KNN-based ceramics.
