Due to its lead-free composition and a unique double polarization hysteresis loop with a large maximum polarization(Pmax)and a small remnant polarization(Pr),AgNbO_(3)-based antiferroelectrics(AFEs)have attracted exte...Due to its lead-free composition and a unique double polarization hysteresis loop with a large maximum polarization(Pmax)and a small remnant polarization(Pr),AgNbO_(3)-based antiferroelectrics(AFEs)have attracted extensive research interest for electric energy storage applications.However,a low dielectric breakdown field(Eb)limits an energy density and its further development.In this work,a highly efficient method was proposed to fabricate high-energy-density Ag(Nb,Ta)O_(3) capacitor films on Si substrates,using a two-step process combining radio frequency(RF)-magnetron sputtering at 450℃and post-deposition rapid thermal annealing(RTA).The RTA process at 700℃led to sufficient crystallization of nanograins in the film,hindering their lateral growth by employing short annealing time of 5 min.The obtained Ag(Nb,Ta)O_(3) films showed an average grain size(D)of~14 nm(obtained by Debye-Scherrer formula)and a slender room temperature(RT)polarization-electric field(P-E)loop(Pr≈3.8 mC·cm^(−2) and P_(max)≈38 mC·cm^(−2) under an electric field of~3.3 MV·cm^(−1)),the P-E loop corresponding to a high recoverable energy density(W_(rec))of~46.4 J·cm^(−3) and an energy efficiency(η)of~80.3%.Additionally,by analyzing temperature-dependent dielectric property of the film,a significant downshift of the diffused phase transition temperature(T_(M2-M3))was revealed,which indicated the existence of a stable relaxor-like AFE phase near the RT.The downshift of the T_(M2-M3) could be attributed to a nanograin size and residual tensile strain of the film,and it led to excellent temperature stability(20-240℃)of the energy storage performance of the film.Our results indicate that the Ag(Nb,Ta)O_(3) film is a promising candidate for electrical energy storage applications.展开更多
Ag（Nb0.8Ta0.2）O3 ceramics were prepared by the traditional solid-state reaction method. The effect of CaF2 addition on the structure and dielectric properties of Ag（Nb0.8Ta0.2）O3 ceramics was investigated. The add...Ag（Nb0.8Ta0.2）O3 ceramics were prepared by the traditional solid-state reaction method. The effect of CaF2 addition on the structure and dielectric properties of Ag（Nb0.8Ta0.2）O3 ceramics was investigated. The addition of CaF2 led the ceramics to a larger grain size and distortion of lattice. With the addition of 4.5 wt.% CaF2, the permittivity of the ceramics increased from 442 to 1028, the dielectric loss decreased sharply from 6.12 × 10^-3 to 8.6 × 10^-4, and the temperature coefficient of capacitance decreased from 1834 ppm/℃ to -50 ppm/℃ （at 1 MHz）. These results indicated that the high permittivity was related with a large grain size, a low grain boundary density, and the weak Ta-O or Nb-O bond strength caused by the addition of CaF2.展开更多
Dielectric properties of Ag（Nb1-xTa）O3 and Bi2O3 doped Ag（Nb1-xTax）O3 solid solutions were investigated. The results show that with the increase of Ta content （x）, the sintering temperature increased, and the di...Dielectric properties of Ag（Nb1-xTa）O3 and Bi2O3 doped Ag（Nb1-xTax）O3 solid solutions were investigated. The results show that with the increase of Ta content （x）, the sintering temperature increased, and the dielectric loss （tanδ） and the temperature coefficient （αc） decreased. Ag（Nb1-xa）O3 （x=0.4） ceramics sintered at 1 100℃ had the highest permittivity （516.8） and a lower tanδ （0.0021） at 1 MHz, and its temperature coefficient was about 191 ppm/℃. The sintering temperature of Ag（Nb1-xTa）O3 （x=0.4） was lowered by the addition of Bi2O3, and its dielectric properties were improved. Ag（Nb0.6Ta0.4）O3 ceramics with 2.5 wt% Bi203 addition presented the optimum dielectric properties （ε=566, tanδ= 0.0007 and αc≈0ppm/℃） （1 MHz）,展开更多
Different ambient conditions for the synthesis of Ag（Nb0.8Ta0.2）O3 ceramics were investi- gated. The Ag（Nb0.8Ta0.2）O3 powder was synthesized at 950 ℃ under different ambient conditions, and then pressed into disk...Different ambient conditions for the synthesis of Ag（Nb0.8Ta0.2）O3 ceramics were investi- gated. The Ag（Nb0.8Ta0.2）O3 powder was synthesized at 950 ℃ under different ambient conditions, and then pressed into disks and sintered between 1060 ℃ and 1100 ℃ respectively. Samples were investigated by X-ray diffraction, scanning electron microscopy and dielectric measurement. The results show that perovskite Ag（Nb0.8Ta0.2）O3 powder was easier to be synthesized in air than in vacuum at 950℃. Grain size of ceramic samples sintered in air was uniform （about 1 μm） and its dielectric loss was small for its high density. However, the samples decomposed greatly and ceramics could hardly be densified when sintered in vacuum, Thus,. higher atmospheric pressure and oxygen atmosphere would benifit the synthesis of Ag （Nb0.8Ta0.2）O3, and suppress its decomposition at high temperature.展开更多
基金support from the National Natural Science Foundation of China (Grant Nos.51772175,52072218,and 52002192)Natural Science Foundation of Shandong Province (Grant Nos.ZR2020QE042,ZR2022ZD39,and ZR2022ME031)+6 种基金the Science,Education and Industry Integration Pilot Projects of Qilu University of Technology (Shandong Academy of Sciences) (Grant Nos.2022GH018 and 2022PY055)support from the Jinan City Science and Technology Bureau (Grant No.2021GXRC055)the Education Department of Hunan Province/Xiangtan University (Grant No.KZ0807969)funding for top talents at Qilu University of Technology (Shandong Academy of Sciences)support from the Jiangsu Province NSFC (Grant No.BK20180764)support from the National Key R&D Program of China (Grant No.2021YFB3601504)Natural Science Foundation of Shandong Province (Grant No.ZR2020KE019).
文摘Due to its lead-free composition and a unique double polarization hysteresis loop with a large maximum polarization(Pmax)and a small remnant polarization(Pr),AgNbO_(3)-based antiferroelectrics(AFEs)have attracted extensive research interest for electric energy storage applications.However,a low dielectric breakdown field(Eb)limits an energy density and its further development.In this work,a highly efficient method was proposed to fabricate high-energy-density Ag(Nb,Ta)O_(3) capacitor films on Si substrates,using a two-step process combining radio frequency(RF)-magnetron sputtering at 450℃and post-deposition rapid thermal annealing(RTA).The RTA process at 700℃led to sufficient crystallization of nanograins in the film,hindering their lateral growth by employing short annealing time of 5 min.The obtained Ag(Nb,Ta)O_(3) films showed an average grain size(D)of~14 nm(obtained by Debye-Scherrer formula)and a slender room temperature(RT)polarization-electric field(P-E)loop(Pr≈3.8 mC·cm^(−2) and P_(max)≈38 mC·cm^(−2) under an electric field of~3.3 MV·cm^(−1)),the P-E loop corresponding to a high recoverable energy density(W_(rec))of~46.4 J·cm^(−3) and an energy efficiency(η)of~80.3%.Additionally,by analyzing temperature-dependent dielectric property of the film,a significant downshift of the diffused phase transition temperature(T_(M2-M3))was revealed,which indicated the existence of a stable relaxor-like AFE phase near the RT.The downshift of the T_(M2-M3) could be attributed to a nanograin size and residual tensile strain of the film,and it led to excellent temperature stability(20-240℃)of the energy storage performance of the film.Our results indicate that the Ag(Nb,Ta)O_(3) film is a promising candidate for electrical energy storage applications.
基金supported by the Program for New Century Excellent Talents in Universities (NCET)the National High-Tech Research and Development Program of China (No. 2007AA03Z423)China Postdoctoral Science Foundation
文摘Ag（Nb0.8Ta0.2）O3 ceramics were prepared by the traditional solid-state reaction method. The effect of CaF2 addition on the structure and dielectric properties of Ag（Nb0.8Ta0.2）O3 ceramics was investigated. The addition of CaF2 led the ceramics to a larger grain size and distortion of lattice. With the addition of 4.5 wt.% CaF2, the permittivity of the ceramics increased from 442 to 1028, the dielectric loss decreased sharply from 6.12 × 10^-3 to 8.6 × 10^-4, and the temperature coefficient of capacitance decreased from 1834 ppm/℃ to -50 ppm/℃ （at 1 MHz）. These results indicated that the high permittivity was related with a large grain size, a low grain boundary density, and the weak Ta-O or Nb-O bond strength caused by the addition of CaF2.
基金the National Natural Science Foundation of China(No.50402011)
文摘Dielectric properties of Ag（Nb1-xTa）O3 and Bi2O3 doped Ag（Nb1-xTax）O3 solid solutions were investigated. The results show that with the increase of Ta content （x）, the sintering temperature increased, and the dielectric loss （tanδ） and the temperature coefficient （αc） decreased. Ag（Nb1-xa）O3 （x=0.4） ceramics sintered at 1 100℃ had the highest permittivity （516.8） and a lower tanδ （0.0021） at 1 MHz, and its temperature coefficient was about 191 ppm/℃. The sintering temperature of Ag（Nb1-xTa）O3 （x=0.4） was lowered by the addition of Bi2O3, and its dielectric properties were improved. Ag（Nb0.6Ta0.4）O3 ceramics with 2.5 wt% Bi203 addition presented the optimum dielectric properties （ε=566, tanδ= 0.0007 and αc≈0ppm/℃） （1 MHz）,
基金SUPPORTED BY NATIONAL NATURAL SCIENCE FOUNDATION OF CHINA( NO. 50402011 ).
文摘Different ambient conditions for the synthesis of Ag（Nb0.8Ta0.2）O3 ceramics were investi- gated. The Ag（Nb0.8Ta0.2）O3 powder was synthesized at 950 ℃ under different ambient conditions, and then pressed into disks and sintered between 1060 ℃ and 1100 ℃ respectively. Samples were investigated by X-ray diffraction, scanning electron microscopy and dielectric measurement. The results show that perovskite Ag（Nb0.8Ta0.2）O3 powder was easier to be synthesized in air than in vacuum at 950℃. Grain size of ceramic samples sintered in air was uniform （about 1 μm） and its dielectric loss was small for its high density. However, the samples decomposed greatly and ceramics could hardly be densified when sintered in vacuum, Thus,. higher atmospheric pressure and oxygen atmosphere would benifit the synthesis of Ag （Nb0.8Ta0.2）O3, and suppress its decomposition at high temperature.
