Temperature dependence of indentation size effect, dislocation pile‐ups, and lattice friction in (001) strontium titanate
Temperature dependence of indentation size effect, dislocation pile‐ups, and lattice friction in (001) strontium titanate
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DOI：
10.1111/jace.15182
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发表时间：
2018
影响因子：
3.9
通讯作者：
Farhan Javaid;K. Johanns;E. Patterson;K. Durst
中科院分区：
文献类型：
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作者：
Farhan Javaid;K. Johanns;E. Patterson;K. Durst
采用Berkovich压头在25℃和350℃下对(001)钛酸锶(STO)单晶进行了纳米压痕实验，分析了温度对压痕尺寸效应和残余压痕周围位错结构的影响。结果表明，在350℃与25℃相比，STO表现出强烈的ISE。残余压痕周围的位错结构已经用腐蚀坑技术进行了解析。在25℃时，位错堆积的扩展比350℃时要短，这也与350℃时较小的尺寸效应有关。用Peach-Koehler力和弹塑性压痕应力场来模拟晶格摩擦应力对位错堆积的影响。根据最外层位错的平衡位置，计算出在25℃和350℃时的平均晶格摩擦应力分别为89和46 MPa。
Nanoindentations with a Berkovich type indenter were performed on (001) strontium titanate (STO) single crystal at 25 degrees C and 350 degrees C, analyzing the influence of temperature on the indentation size effect (ISE) and dislocation structure around the residual impression. It is found that the STO exhibits an ISE, which is strongly reduced at 350 degrees C compared to 25 degrees C. The dislocation structure around the residual impression has been resolved using an etch-pit technique. At 25 degrees C, the extension of the dislocation pile-ups were found to be shorter as compared to 350 degrees C. This also correlates with the smaller size effects at 350 degrees C. Peach-Koehler forces and the elastic-plastic indentation stress field were used to model the influence of the lattice frictional stress on the dislocation pile-ups. Based on an equilibrium position of the outermost dislocations, the average lattice frictional stresses were calculated to be 89 MPa and 46 MPa at 25 degrees C and 350 degrees C, respectively.