. "State College, PA, USA" . . . "The Pennsylvania State University Materials Research Institute N228 Millennium Science Complex University Park, PA 16802 USA" . "24220" . "Nonlinear extrinsic piezoelectricity in lead titanate due to 90\u00B0 domain wall pinning" . "Extrinsic piezoelectricity; domain wall; lead titanate"@en . . "Mokr\u00FD, Pavel" . . "P(GA13-10365S), P(GAP204/10/0616)" . . "Nonlinear extrinsic piezoelectricity in lead titanate due to 90\u00B0 domain wall pinning"@en . "RIV/46747885:24220/13:#0002432" . . "Nonlinear extrinsic piezoelectricity in lead titanate due to 90\u00B0 domain wall pinning"@en . "Sluka, Tom\u00E1\u0161" . . "3"^^ . . "Group of perovskite materials is still playing the essential role in a construction of contemporary electromechanical transducers. An increased number of regulations concerning the use of hazardous substances has triggered a vivid search for equally well performing piezoelectric materials but without the toxic lead. One of the possibilities to increase the piezoelectric response of lead-free piezoelectric perovskites is to employ so called extrinsic contributions (i.e. motion of ferroelastic domain walls) to piezoelectricity in some controlled manner. The key factor which controls the macroscopic value of the extrinsic contributions to piezoelectricity is the restoring force acting on a domain wall, when it is shifted from its equilibrium position. Considering the bulk properties of perovskites, the main contribution to the restoring force comes from the interaction of domain walls with so called pinning centers such as crystal lattice point defects or dislocations. We have developed a thermodynamic Phase-Field-Model of a 90\u00B0 domain wall interacting with a pinning center (see Fig. 1). We have performed a series of massive numerical computations, which resulted in macroscopic values of piezoelectric coefficients. The results of our computations indicated that the extrinsic piezoelectricity is generally nonlinear. We computed the linear and nonlinear contribution to the extrinsic piezoelectricity as a function of pinning centers concentration. The results indicated a cubic relationship between linear and nonlinear permittivity for this type of extrinsic contribution, which is quite different from that of the lattice contribution derived from Landau theory. These results are in a good agreement with a simple but rather general thermodynamic model. We propose that such results can be used for the analysis of experimental data and for the characterization of lead-free ceramics and single crystals." . . "CD-IWATMD-2013" . "1"^^ . . . . "Nonlinear extrinsic piezoelectricity in lead titanate due to 90\u00B0 domain wall pinning" . "Group of perovskite materials is still playing the essential role in a construction of contemporary electromechanical transducers. An increased number of regulations concerning the use of hazardous substances has triggered a vivid search for equally well performing piezoelectric materials but without the toxic lead. One of the possibilities to increase the piezoelectric response of lead-free piezoelectric perovskites is to employ so called extrinsic contributions (i.e. motion of ferroelastic domain walls) to piezoelectricity in some controlled manner. The key factor which controls the macroscopic value of the extrinsic contributions to piezoelectricity is the restoring force acting on a domain wall, when it is shifted from its equilibrium position. Considering the bulk properties of perovskites, the main contribution to the restoring force comes from the interaction of domain walls with so called pinning centers such as crystal lattice point defects or dislocations. We have developed a thermodynamic Phase-Field-Model of a 90\u00B0 domain wall interacting with a pinning center (see Fig. 1). We have performed a series of massive numerical computations, which resulted in macroscopic values of piezoelectric coefficients. The results of our computations indicated that the extrinsic piezoelectricity is generally nonlinear. We computed the linear and nonlinear contribution to the extrinsic piezoelectricity as a function of pinning centers concentration. The results indicated a cubic relationship between linear and nonlinear permittivity for this type of extrinsic contribution, which is quite different from that of the lattice contribution derived from Landau theory. These results are in a good agreement with a simple but rather general thermodynamic model. We propose that such results can be used for the analysis of experimental data and for the characterization of lead-free ceramics and single crystals."@en . "91965" . "RIV/46747885:24220/13:#0002432!RIV14-GA0-24220___" . . . "Tagantsev, Alexander K." . . . "[0E5DAF1C3F90]" . .