The effect of doping metal ions in ferroelastic Pb3(PO4)2 (PPO) on the polar nature of domain boundaries (DBs) was investigated using a second harmonic generation (SHG) microscope. It has been already reported that DBs of non-doped PPO is SH active and polar. The present study reveals that DBs of Ca-doped and Mg-doped PPO show greatly enhanced SH activity. This indicates that doping by metal ions enhances the polar nature of the DBs of PPO. This is important for future applications of DB nanotechnology. The enhancement of SH intensity is explained by a larger displacement of Ca2+ and Mg2+ ions in DBs due to smaller ionic radii. Analyses of the SH anisotropy experiments reveal that the symmetry-adapted W-wall belongs to monoclinic m and the non-adapted W'-wall to monoclinic 2. Both point groups are classified as the polar classes, which coincides with the case of pure PPO.

中文翻译：

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通过掺杂二价金属离子增强铁弹性 Pb3(PO4)2 中畴边界的极性

使用二次谐波发生 (SHG) 显微镜研究了在铁弹性 Pb3(PO4)2 (PPO) 中掺杂金属离子对畴界 (DB) 极性性质的影响。据报道，非掺杂 PPO 的 DB 是 SH 活性和极性的。本研究表明，Ca 掺杂和 Mg 掺杂的 PPO 的 DB 显示出大大增强的 SH 活性。这表明金属离子的掺杂增强了 PPO 的 DB 的极性。这对于 DB 纳米技术的未来应用很重要。由于较小的离子半径，DBs 中 Ca2+ 和 Mg2+ 离子的较大位移解释了 SH 强度的增强。SH各向异性实验的分析表明，对称适应的W-wall属于单斜m，非适应的W'-wall属于单斜2。两个点群都被归类为极性类，