This paper deals with possible experimental signatures of the so-called polar nanoregions in lead-based perovskite relaxors.It outlines both traditional and alternative approaches to these signatures.It is argued that...This paper deals with possible experimental signatures of the so-called polar nanoregions in lead-based perovskite relaxors.It outlines both traditional and alternative approaches to these signatures.It is argued that the concept of polar nanoregions is useful but largely speculative.Polar nanoregions are compared with ferroelectric nanodomains.Qualitative explanation of the principal"relaxor"properties of PMN are discussed in both frameworks.It is argued that polarization as a vector may not be well defined at any nanometric region in PMN Crystal.展开更多
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
基金This work was partly supported by the Czech Science Foundation(Project GACR P204/10/0616).
文摘This paper deals with possible experimental signatures of the so-called polar nanoregions in lead-based perovskite relaxors.It outlines both traditional and alternative approaches to these signatures.It is argued that the concept of polar nanoregions is useful but largely speculative.Polar nanoregions are compared with ferroelectric nanodomains.Qualitative explanation of the principal"relaxor"properties of PMN are discussed in both frameworks.It is argued that polarization as a vector may not be well defined at any nanometric region in PMN Crystal.
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.
