Abstract
BaTiO3 single crystals were deformed in compression along the langle 110rangle crystal axis to study the plastic deformability and dislocation structures at high temperatures under different loading conditions. The yield strength is determined from stress–strain curves under strain rate control, load control, strain rate cycling tests, and under step-wise loading conditions to elucidate the impact of measurement approach in yield strength behavior. A comparison between the chosen methods based on stress-dependent strain rate plots indicates that load control measurements are a suitable alternative to the commonly used strain rate-control experiments in metals. This allows avoiding overloading and providing an estimate of the overall achievable strain rates in a ceramic. Activation energies and activation volumes in the temperature range of 1100–1170 °C indicate a similar mechanical deformation behavior to SrTiO3.Graphical abstract
Highlights
Dislocation-based functionality in ceramics has attracted much attention in recent years
With increasing deformation temperature from 1100 to 1170 °C, dislocation loops or dislocation loop segments were observed more often than straight dislocations [marked individually in (e)–(f)], indicating that dislocation configuration can be tuned by changing the deformation conditions
The yield strength and the flow stress of 110 -oriented BaTiO3 single crystals mainly depend on temperature and little on the selected loading conditions
Summary
Dislocation-based functionality in ceramics has attracted much attention in recent years. Domain walls are borders between regions with different spontaneous polarization orientations. Such nucleation and pinning of ferroelectric domain walls at dislocations has been predicted in several simulations [5], leading to a change in ferroelectric and ferroelastic domain structure, polarization, and coercive field (electric field at which domains switch) [6]. Most of these predictions have been experimentally demonstrated only in thin films [7] or around indentations [8]. Plastic deformability for ferroelectric KNbO3 single crystals has been addressed [9, 10] and the influence of the dislocation imprint at high temperature on the dielectric and piezoelectric properties of bulk BaTiO3 has been reported [4]
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