Microstructure and EDS Contact Surfaces Characterization for Statistical Analysis of Doped BaTiO3-Ceramics

Barium-titanate based ceramics belongs to one of very important group of functional ceramics that can be used on a large scale of applications. The properties of BaTiO3 based ceramics are fundamentally correlated with grain boundary effects and consequently with the microstructure developed during sintering process. The purpose of this paper is an investigation of the effects of various dopants (La, Nb, Er, Yb, Ho, Sb) on the microstructure properties and contact surfaces. The grain size and microstructure were investigated using SEM and EDS analysis. SEM and EDS studies were performed by scanning electron microscopy (JEOL-JSM 5300) equipped with EDS (QX 2000S) system

Identification of two-dimensional prestress fields in inhomogeneous plates

Based on the model of in-plane oscillations of inhomogeneous prestressed plates, the new inverse problems of identifying the components of the prestress tensor via acoustic response probing are considered for the plates with and without holes and inclusions; the prestress components are assumed to be functions of two coordinates. Prestresses were set as a result of solving auxiliary problems of static loading of plates by some initial mechanical load. To solve the main and auxiliary problems of calculating the plates’ displacement functions, a finite element (FE) scheme was developed based on the derived corresponding weak problem statements, implemented in the form of software systems in the FE package FreeFem++. Rectangular plates clamped along one face, both solid and having a hole or a rigid insert, were considered. Inverse problems of identification of three prestress functions depending on two coordinates are formulated on the basis of additional data about the acoustic response on the non-clamped edges of the plates as a result of considering several sets of probing loads at several frequencies. In view of the nonlinearity of the inverse problems under study, an iterative approach was developed to solve them, which combines solving the direct problems for current approximations of the desired functions and the determination of the corresponding corrections from the operator equation built at each iteration. To solve the operator equation, a projection method has been employed that allows one to present the corrections in the form of expansions in terms of some smooth given functions and reduce the problem solution to the study of ill-conditioned SLAEs with respect to sets of the expansion coefficients using the A. N. Tikhonov method. The results of computational experiments on the simultaneous identification of two-dimensional prestress fields corresponding to various types of initial actions on the considered plates are discussed

Mechanically Activated BaTiO3 Microstructure Fractal Nature

Increasing demands on the quality of electronic ceramics requires a well-controlled correlation between particle morphology and processing conditions. Since mechanical activation is one of the methods for modification of physico-chemical properties of dispersed systems, in this study a correlation between the densification rate microstructure evolution and fractal nature of mechanically activated BaTiO3 has been analyzed. The high purity commercial BaTiO3 powder was mechanically activated in a planetary ball mill in a continual regime for 60 and 120 minutes. Sintering under non isothermal conditions was carried out up to 1380 °C. The shrinkage behaviour of mechanically activated samples, has been analyzed by a sensitive dilatometer. Densification rate as a function of relative density for different activation times has been calculated.Microstructure investigations of sintered samples were carried out, using a scanning electron microscope (SEM). The presented results enable establishing processing parameters that are indisensable for obtaining materials with advanced properties

Mechanically Activated BaTiO3 Microstructure Fractal Nature

Increasing demands on the quality of electronic ceramics requires a well-controlled correlation between particle morphology and processing conditions. Since mechanical activation is one of the methods for modification of physico-chemical properties of dispersed systems, in this study a correlation between the densification rate microstructure evolution and fractal nature of mechanically activated BaTiO3 has been analyzed. The high purity commercial BaTiO3 powder was mechanically activated in a planetary ball mill in a continual regime for 60 and 120 minutes. Sintering under non isothermal conditions was carried out up to 1380 °C. The shrinkage behaviour of mechanically activated samples, has been analyzed by a sensitive dilatometer. Densification rate as a function of relative density for different activation times has been calculated.Microstructure investigations of sintered samples were carried out, using a scanning electron microscope (SEM). The presented results enable establishing processing parameters that are indisensable for obtaining materials with advanced properties