PbZrO_(3)-based antiferroelectric(AFE)ceramics are promising dielectrics for high-energy-density capacitors due to their reversible phase transitions during charge-discharge cycles.In this work,a new composition serie...PbZrO_(3)-based antiferroelectric(AFE)ceramics are promising dielectrics for high-energy-density capacitors due to their reversible phase transitions during charge-discharge cycles.In this work,a new composition series,[Pb_(0.93-x)La_(0.02)(Li_(1/2)Bi_(1/2))_(x)Sr_(0.04)][Zr_(0.57)Sn_(0.34)Ti_(0.09)]O_(3),with Li^(+)and Bi^(3+)substitution of Pb^(2+)at x=0,0.04,0.08,0.12,0.16 is investigated for the microstructure evolution,ferroelectric(FE)and dielectric properties.It is found that Li^(+) and Bi^(3+) substitution can significantly reduce the sintering temperature and simultaneously enhance the dielectric breakdown strength.An ultrahigh energy efficiency(94.0%)and a large energy density(3.22 J/cm^(3))are achieved in the composition of x=0.12 with a low sintering temperature(1075℃).展开更多
The present work reports the synthesis, characterization, photoluminescence and photocatalytic activity of Eu^(3+)(1 mol%-11 mol%) doped and Li^+(0.5 mol%-5 mol%) co-doped Bi_2 O_3 nanophosphors(NPs) by sonochemical m...The present work reports the synthesis, characterization, photoluminescence and photocatalytic activity of Eu^(3+)(1 mol%-11 mol%) doped and Li^+(0.5 mol%-5 mol%) co-doped Bi_2 O_3 nanophosphors(NPs) by sonochemical method. The average particle size was estimated using powder X-ray diffraction(PXRD)and transmission electron microscopy(TEM) and is found to be in the range of 30-35 nm. The scanning electron microscopy(SEM) images were highly dependent on sonication time and concentration of epigallocatechin gallate(EGCG) bio-surfactant. The energy gap of doped and co-doped Bi_2 O_3 nanophosphors was estimated using Kubelka-Munk(K-M) function and is found to be in the range of2.9-3.08 eV. The effect of Li+ co-doping on luminescence of optimized Bi_2 O_3:Eu^(3+) was studied and is found about more than 3 fold enhancement of emission intensity. Judd-Ofelt parameters(Ω_2, Ω_4 and Ω_6).transition probabilities(A_T), quantum efficiency(η), luminescence lifetime(τ_(rad)), color chromaticity coordinates(CIE) and correlated color temperature(CCT) values were estimated from the emission spectra and are discussed in detail. The estimated CIE chromaticity co-ordinates are very close to the NTSC(National Television Standard Committee) standard value of red emission. The synthesized NPs show excellent photocatalytic activity of acid red-88 under UV-light irradiation, which can degrade 98.1% in60 min. The decreasing electron-hole pair recombination rate with quick electron transfer ability is predominantly ascribed to the balance between crystallite size, morphology, band gap, defects, surface area, etc. These results show a light for the use of sonochemical route of Bi_2 O_3:Eu^(3+):Li^+ in solid state display and photocatalytic applications.展开更多
Lead-free (1-x)Sr0.1Bi0.45Na0.45TiO3-xBi0.5Li0.5TiO3 (x = 0-0.4) ceramics were successfully prepared by a solid-state reaction technique. The effects of amount of Bi0.5Li0.5TiO3 on structure and electrical properties ...Lead-free (1-x)Sr0.1Bi0.45Na0.45TiO3-xBi0.5Li0.5TiO3 (x = 0-0.4) ceramics were successfully prepared by a solid-state reaction technique. The effects of amount of Bi0.5Li0.5TiO3 on structure and electrical properties were examined. The X-ray diffraction (XRD) analysis revealed that all the investigated specimens have a perovskite structure. An obvious change in microstructure with the increase of Bi0.5Li0.5TiO3 concentration was observed. This study demonstrated that relaxor could be stabilized in Sr0.1Bi0.45Na0.45TiO3 based ceramics by lowering the tolerance factor and electronegativity difference. Besides, a dielectric anomaly related to thermal evolution of crystallographic symmetry was emerged at the depolarization temperature. Upon incorporation of 26 mol% Bi0.5Li0.5TiO3, the specimens were able to withstand an electric field intensity of 106.9 kV/cm with an energy density of 0.88 J/cm(3) and an energy efficiency of 65%.展开更多
基金supported by the U.S.Department of Energy’s Office of Energy Efficiency and Renewable Energy(EERE)under the Advanced Manufacturing Office(AMO)Award Number DEEE0009105.
文摘PbZrO_(3)-based antiferroelectric(AFE)ceramics are promising dielectrics for high-energy-density capacitors due to their reversible phase transitions during charge-discharge cycles.In this work,a new composition series,[Pb_(0.93-x)La_(0.02)(Li_(1/2)Bi_(1/2))_(x)Sr_(0.04)][Zr_(0.57)Sn_(0.34)Ti_(0.09)]O_(3),with Li^(+)and Bi^(3+)substitution of Pb^(2+)at x=0,0.04,0.08,0.12,0.16 is investigated for the microstructure evolution,ferroelectric(FE)and dielectric properties.It is found that Li^(+) and Bi^(3+) substitution can significantly reduce the sintering temperature and simultaneously enhance the dielectric breakdown strength.An ultrahigh energy efficiency(94.0%)and a large energy density(3.22 J/cm^(3))are achieved in the composition of x=0.12 with a low sintering temperature(1075℃).
基金supported by VGST,Govt.of Karnataka,India(VGST/K-FIST-L1/2016-17/GRD-360)
文摘The present work reports the synthesis, characterization, photoluminescence and photocatalytic activity of Eu^(3+)(1 mol%-11 mol%) doped and Li^+(0.5 mol%-5 mol%) co-doped Bi_2 O_3 nanophosphors(NPs) by sonochemical method. The average particle size was estimated using powder X-ray diffraction(PXRD)and transmission electron microscopy(TEM) and is found to be in the range of 30-35 nm. The scanning electron microscopy(SEM) images were highly dependent on sonication time and concentration of epigallocatechin gallate(EGCG) bio-surfactant. The energy gap of doped and co-doped Bi_2 O_3 nanophosphors was estimated using Kubelka-Munk(K-M) function and is found to be in the range of2.9-3.08 eV. The effect of Li+ co-doping on luminescence of optimized Bi_2 O_3:Eu^(3+) was studied and is found about more than 3 fold enhancement of emission intensity. Judd-Ofelt parameters(Ω_2, Ω_4 and Ω_6).transition probabilities(A_T), quantum efficiency(η), luminescence lifetime(τ_(rad)), color chromaticity coordinates(CIE) and correlated color temperature(CCT) values were estimated from the emission spectra and are discussed in detail. The estimated CIE chromaticity co-ordinates are very close to the NTSC(National Television Standard Committee) standard value of red emission. The synthesized NPs show excellent photocatalytic activity of acid red-88 under UV-light irradiation, which can degrade 98.1% in60 min. The decreasing electron-hole pair recombination rate with quick electron transfer ability is predominantly ascribed to the balance between crystallite size, morphology, band gap, defects, surface area, etc. These results show a light for the use of sonochemical route of Bi_2 O_3:Eu^(3+):Li^+ in solid state display and photocatalytic applications.
基金Financial supports of the National Natural Science Foundation of China，the Natural Science Foundation of Guangxi (Grant No.2014GXNSFBA118254) are gratefully acknowledged by the authors
文摘Lead-free (1-x)Sr0.1Bi0.45Na0.45TiO3-xBi0.5Li0.5TiO3 (x = 0-0.4) ceramics were successfully prepared by a solid-state reaction technique. The effects of amount of Bi0.5Li0.5TiO3 on structure and electrical properties were examined. The X-ray diffraction (XRD) analysis revealed that all the investigated specimens have a perovskite structure. An obvious change in microstructure with the increase of Bi0.5Li0.5TiO3 concentration was observed. This study demonstrated that relaxor could be stabilized in Sr0.1Bi0.45Na0.45TiO3 based ceramics by lowering the tolerance factor and electronegativity difference. Besides, a dielectric anomaly related to thermal evolution of crystallographic symmetry was emerged at the depolarization temperature. Upon incorporation of 26 mol% Bi0.5Li0.5TiO3, the specimens were able to withstand an electric field intensity of 106.9 kV/cm with an energy density of 0.88 J/cm(3) and an energy efficiency of 65%.
