Room-Temperature Plastic Deformation of Strontium Titanate Crystals Grown from Different Chemical Compositions
Oxide materials have the potential to exhibit superior mechanical properties in terms of high yield point, high melting point, and high chemical stability. Despite this, they are not widely used as a structural material due to their brittle nature. However, this study shows enhanced room-temperature plasticity of strontium titanate (SrTiO3) crystals through the control of the chemical composition. It is shown that the deformation behavior of SrTiO3 crystals at room temperature depends on the Sr/Ti ratio. It was found that flow stresses in deforming SrTiO3 crystals grown from a powder with the particular ratio of Sr/Ti = 1.04 are almost independent of the strain rate because of the high mobility of dislocations in such crystals. As a result, the SrTiO3 crystals can deform by dislocation slip up to a strain of more than 10%, even at a very high strain rate of 10% per second. It is thus demonstrated that SrTiO3 crystals can exhibit excellent plasticity when chemical composition in the crystal is properly controlled.
Crystal Dislocations: Their Impact on Physical Properties of Crystals
It is rare to find technical applications involving a material of any crystal structure that is not impacted by dislocations—which affect the material’s mechanical properties, interfaces, martensitic phase transformations, crystal growth, and electronic properties, to name a few. [...]
Modeling dislocation cores in Sr Ti O 3 using the Peierls-Nabarro model
We have recently determined dislocation core structures in complex minerals relevant to the Earth's mantle using the Peierls-Nabarro model. In this approach, the original Peierls-Nabarro model is coupled with first-principles calculations of generalized stacking fault. In order to test the reliability of such calculations, we study here the dislocation core properties in a perovskite-structured material, $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$, for which a lot of experimental information are available. Four different slip systems have been investigated in $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$: ⟨100⟩{010}, ⟨100⟩{011}, ⟨110⟩{001}, and $⟨110⟩{1\overline{1}0}$. $⟨110⟩{1\overline{1}0}$ exhibits the lower lattice friction due to core spreading, and the next easiest slip system is found to be ⟨100⟩{010}. It is shown that our results (dislocation core spreading and Peierls stress values) are in perfect agreement with experiments (transmission electron microscopy model of core structure and mechanical properties), providing an interesting validation of the Peierls-Nabarro model on complex materials.