RESUMO
In this work a multi-technique characterization was performed for the first time to trace the influence of structural defects on the physical properties of PbTiO3 ferroelectrics. The structural defects were generated by the mechanical activation in the pressure range of 40-320 MPa, by combining a uniaxial strain with a shear deformation in the Bridgman anvils. The induced defectivity of PbTiO3 was assessed via calculation of unit cell parameters, estimation of the regions of coherent scattering and analysis of micro-deformations. The Debye characteristic temperature, the static mean-square displacement, the Debye-Waller isotropic factor, the vibrational spectra and dielectric properties of the activated PbTiO3 ceramics are presented. The high-quality PbTiO3 ceramics was prepared without modifiers, hence, changing the concentration of structural defects via mechanical activation constitutes a chemically clean method for fine tuning of the dielectric properties of PbTiO3.
RESUMO
Magnetic iron oxide nanoparticles doped with samarium were prepared by solvothermal polyol method. An introduction of 2,2'-bipyridine during the synthesis reduces the particle diameter to about 9nm in average. The difference in physical and magnetic properties of the samples prepared with and without capping agent was outlined on the basis of complex characterization by a number of experimental techniques. The characteristics of resulted product make it suitable for biomedical applications, for instance, as a contrast agent for MRI.
