(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3)relaxor-type ferroelectric ceramics was obtained via classical solid-state reaction.The hysteresis loop results were discussed in the frame of ergodicity criter...(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3)relaxor-type ferroelectric ceramics was obtained via classical solid-state reaction.The hysteresis loop results were discussed in the frame of ergodicity criterium around the characteristic ferroelectric relaxor freezing temperature.Slimer hysteresis loops were observed below the freezing temperature reflecting an ergodic relaxor behavior.Above this temperature,estimated around 223K for the studied system,larger and unsaturated like ferroelectric hysteresis loops were observed.This temperature also coincides with the slope change on maximum polarization and inflection point of remnant polarization curves.Energy storage,energy loss and efficiency values were determined in a wide temperature range.While the recoverable energy density shows relatively low values(0.23 J/cm^(3)),there are interesting behaviors for this parameter and for the efficiency,since the two physical quantities increase versus temperature and the efficiency even reaches the value of 97%.展开更多
The paper presents the structural and ferroelectric results for Sr_(1-x)Ba_(x)Bi_(2)Nb_(2)O_(9)(x=0.30;0.85)thin films,which were obtained by using dip-coating.The solutions containing the desirable ions were prepared...The paper presents the structural and ferroelectric results for Sr_(1-x)Ba_(x)Bi_(2)Nb_(2)O_(9)(x=0.30;0.85)thin films,which were obtained by using dip-coating.The solutions containing the desirable ions were prepared from the powders of the previous studied ceramic samples.The films were deposited at room temperature on Fluorine-doped Tin Oxide(FTO)substrates and submitted to a heat treatment for crystallization.The films were characterized by using scanning microscopy electronic,energy dispersive spectroscopy and ellipsometry.Hysteresis ferroelectric loops were obtained,at room temperature,by using a Sawyer-Tower circuit at several frequencies.A well-defined grain structure was observed for both compositions.The energy dispersive spectroscopy(EDS)measurements revealed the presence of the corresponding elements from the chemical composition of the ceramic systems.The band-gap energy was around 3.3 eV for both samples.Typical hysteresis loops for normal and relaxor ferroelectrics were obtained for x=0.30 and 0.85,respectively.展开更多
A lead-free relaxor ferroelectric,Sr_(0.15)Ba_(0.85)Bi_(2)Nb_(2)O_(9),was synthesized via solid-state reaction and the temperature-dependence of the heat capacity was measured in a wide temperature range.The dielectri...A lead-free relaxor ferroelectric,Sr_(0.15)Ba_(0.85)Bi_(2)Nb_(2)O_(9),was synthesized via solid-state reaction and the temperature-dependence of the heat capacity was measured in a wide temperature range.The dielectric permittivity was also measured between 500 Hz and 5 MHz in the same temperature range.No anomaly has been detected in the heat capacity curve for the whole temperature range covered in the present experiments,while broad peaks have been observed in the dielectric permittivity with high frequency dispersion.A typical relaxor behavior has been observed from the dielectric analysis.The Debye's temperature has showed a minimum value near the freezing temperature.The results are discussed considering the spin-glass model and the high frequency dispersion,which has been observed for the studied relaxor system.展开更多
Switching mechanisms and energy-storage properties have been investigated in(Pb_(0.98)La_(0.02)T(Zr_(0.95)Ti_(0.05)T_(0.995O_(3)) antiferroelectric ceramics.The electric field dependence of polarization(P–E hysteresi...Switching mechanisms and energy-storage properties have been investigated in(Pb_(0.98)La_(0.02)T(Zr_(0.95)Ti_(0.05)T_(0.995O_(3)) antiferroelectric ceramics.The electric field dependence of polarization(P–E hysteresis loops)indicates that both the ferroelectric(FE)and antiferroelectric(AFE)phases coexist,being the AFE more stable above 100℃.It has been observed that the temperature has an important influence on the switching parameters.On the other hand,the energy-storage density,which has been calculated from the P–E hysteresis loops,shows values higher than 1 J/cm^(3) for temperatures above 100℃ with around 73%of efficiency as average.These properties indicate that the studied ceramic system reveals as a promising AFE material for energy-storage devices application.展开更多
基金the Third World Academy of Sciences(RG/PHYS/LA No.99-050,02-225 and 05-043)support and ICTP for financial support of Latin-American Network of Ferroelectric Materials(NT-02)+1 种基金the National Program for Nanoscience and Nanotechnology of Cuba(Project No.PN211LH008-035)the National Program for Basic Sciences of Cuba(Project No.PN223LH010-023).
文摘(Pb_(0.8)Ba_(0.2))[(Zn_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)]O_(3)relaxor-type ferroelectric ceramics was obtained via classical solid-state reaction.The hysteresis loop results were discussed in the frame of ergodicity criterium around the characteristic ferroelectric relaxor freezing temperature.Slimer hysteresis loops were observed below the freezing temperature reflecting an ergodic relaxor behavior.Above this temperature,estimated around 223K for the studied system,larger and unsaturated like ferroelectric hysteresis loops were observed.This temperature also coincides with the slope change on maximum polarization and inflection point of remnant polarization curves.Energy storage,energy loss and efficiency values were determined in a wide temperature range.While the recoverable energy density shows relatively low values(0.23 J/cm^(3)),there are interesting behaviors for this parameter and for the efficiency,since the two physical quantities increase versus temperature and the efficiency even reaches the value of 97%.
基金the Third World Academy of Sciences(RG/PHYS/LA Nos.99-050,02-225 and 05-043)to the ICTP,Trieste-Italy,for financial support of Latin-American Network of Ferroelectric Materials(NET-43,currently NT-02).
文摘The paper presents the structural and ferroelectric results for Sr_(1-x)Ba_(x)Bi_(2)Nb_(2)O_(9)(x=0.30;0.85)thin films,which were obtained by using dip-coating.The solutions containing the desirable ions were prepared from the powders of the previous studied ceramic samples.The films were deposited at room temperature on Fluorine-doped Tin Oxide(FTO)substrates and submitted to a heat treatment for crystallization.The films were characterized by using scanning microscopy electronic,energy dispersive spectroscopy and ellipsometry.Hysteresis ferroelectric loops were obtained,at room temperature,by using a Sawyer-Tower circuit at several frequencies.A well-defined grain structure was observed for both compositions.The energy dispersive spectroscopy(EDS)measurements revealed the presence of the corresponding elements from the chemical composition of the ceramic systems.The band-gap energy was around 3.3 eV for both samples.Typical hysteresis loops for normal and relaxor ferroelectrics were obtained for x=0.30 and 0.85,respectively.
基金The authors wish to express their thanks to the Third World Academy of Sciences(RG/PHYS/LA Nos.99-050,02-225 and 05-043)to ICTP,Trieste,Italy,for the financial support of Latin-American Network of Ferroelectric Materials(NET-43).Thanks to CNPq and FAPEMIG agencies from Brazil.APB acknowledges to the Conseil Regional Languedoc-Roussillon for her invitation to the University of Nîmes,France.Thanks to the Embassy of France in Havana,Cuba,for financial support for the scientific cooperation between the University of Nîmes and the Havana University。
文摘A lead-free relaxor ferroelectric,Sr_(0.15)Ba_(0.85)Bi_(2)Nb_(2)O_(9),was synthesized via solid-state reaction and the temperature-dependence of the heat capacity was measured in a wide temperature range.The dielectric permittivity was also measured between 500 Hz and 5 MHz in the same temperature range.No anomaly has been detected in the heat capacity curve for the whole temperature range covered in the present experiments,while broad peaks have been observed in the dielectric permittivity with high frequency dispersion.A typical relaxor behavior has been observed from the dielectric analysis.The Debye's temperature has showed a minimum value near the freezing temperature.The results are discussed considering the spin-glass model and the high frequency dispersion,which has been observed for the studied relaxor system.
基金the Third World Academy of Sciences(RG/PHYS/LA Nos.99-050,02-225 and 05-043)the ICTP,Trieste-Italy,for financial support of Latin-American Network of Ferroelectric Materials(NET-43).
文摘Switching mechanisms and energy-storage properties have been investigated in(Pb_(0.98)La_(0.02)T(Zr_(0.95)Ti_(0.05)T_(0.995O_(3)) antiferroelectric ceramics.The electric field dependence of polarization(P–E hysteresis loops)indicates that both the ferroelectric(FE)and antiferroelectric(AFE)phases coexist,being the AFE more stable above 100℃.It has been observed that the temperature has an important influence on the switching parameters.On the other hand,the energy-storage density,which has been calculated from the P–E hysteresis loops,shows values higher than 1 J/cm^(3) for temperatures above 100℃ with around 73%of efficiency as average.These properties indicate that the studied ceramic system reveals as a promising AFE material for energy-storage devices application.
