This paper describes a detailed analysis of the dependence of Raman scattering intensity on the polarization of the incident and inelastically scattered light in PbSc_(0.5)Nb_(0.5)O_(3)(PSN)single crystals and epitaxi...This paper describes a detailed analysis of the dependence of Raman scattering intensity on the polarization of the incident and inelastically scattered light in PbSc_(0.5)Nb_(0.5)O_(3)(PSN)single crystals and epitaxially compressed thin films grown on(100)-oriented MgO substrates.It is found that there are significant differences between the properties of the crystals and films,and that these differences can be attributed to the anticipated structural differences between these two forms of the same material.In particular,the scattering characteristics of the oxygen octahedra breathing mode near 810 cm^(-1) indicate a ferroelectric state for the crystals and a relaxor state for the films,which is consistent with the dielectric behaviors of these materials.展开更多
Three types of BaTiO3 core-amorphous nanoshell composite ceramics were processed from the same core-shell powder by standard sintering,spark-plasma sintering and two-step sintering techniques and characterized by XRD,...Three types of BaTiO3 core-amorphous nanoshell composite ceramics were processed from the same core-shell powder by standard sintering,spark-plasma sintering and two-step sintering techniques and characterized by XRD,HRSEM and broadband dielectric spectroscopy in the frequency range 10^(3)-10^(13)Hz including the THz and IR range.The samples differed by porosity and by the amount of interdiffusion from the cores to shells,in correlation with their increasing porosity.The dielectric spectra were also calculated using suitable models based on effective medium approximation.The measurements revealed a strong dielectric dispersion below the THz range,which cannot be explained by the modeling,and whose strength was in correlation with the degree of interdiffusion.It is assigned to an effect of the interdiffusion layers,giving rise to a strong interfacial polarization.It appears that the high-frequency dielectric spectroscopy is an extremely sensitive tool for detection of any gradient layers and sample inhomogeneities even in dielectric materials with negligible conductivity.展开更多
基金supported by the Czech Science Foundation(Projects CSF 15-04121S and 15-15123S)the United Stated Office of Naval Research(Grant No.N00014-12-1-1045)the Natural Science&Engineering Research Council of Canada(NSERC).
文摘This paper describes a detailed analysis of the dependence of Raman scattering intensity on the polarization of the incident and inelastically scattered light in PbSc_(0.5)Nb_(0.5)O_(3)(PSN)single crystals and epitaxially compressed thin films grown on(100)-oriented MgO substrates.It is found that there are significant differences between the properties of the crystals and films,and that these differences can be attributed to the anticipated structural differences between these two forms of the same material.In particular,the scattering characteristics of the oxygen octahedra breathing mode near 810 cm^(-1) indicate a ferroelectric state for the crystals and a relaxor state for the films,which is consistent with the dielectric behaviors of these materials.
基金supported by the Academy of Sci-ences of the Czech Republic(project AVOZ 10100520)the Czech Science Foundation(project 202/09/0430)by COST action MP904.
文摘Three types of BaTiO3 core-amorphous nanoshell composite ceramics were processed from the same core-shell powder by standard sintering,spark-plasma sintering and two-step sintering techniques and characterized by XRD,HRSEM and broadband dielectric spectroscopy in the frequency range 10^(3)-10^(13)Hz including the THz and IR range.The samples differed by porosity and by the amount of interdiffusion from the cores to shells,in correlation with their increasing porosity.The dielectric spectra were also calculated using suitable models based on effective medium approximation.The measurements revealed a strong dielectric dispersion below the THz range,which cannot be explained by the modeling,and whose strength was in correlation with the degree of interdiffusion.It is assigned to an effect of the interdiffusion layers,giving rise to a strong interfacial polarization.It appears that the high-frequency dielectric spectroscopy is an extremely sensitive tool for detection of any gradient layers and sample inhomogeneities even in dielectric materials with negligible conductivity.
