The improper ferroelectric CsNbW2O9 has recently been highlighted as the first material outside the manganite family to exhibit a similar meandering, sixfold domain structure to that responsible for enhanced and diminished conduction at charged domain walls in the rare earth manganites. While there is no current evidence for variation in domain wall conduction relative to bulk in CsNbW2O9, the similarities in microstructure strongly suggest that charged domain walls are present in this material. Herein, we report a comprehensive study of the domain microstructure of CsNbW2O9 by both piezoresponse force microscopy and transmission electron microscopy to reveal that there are, in fact, clear distinctions in the domain structure of the two systems. Constraints arising from the crystal structure of CsNbW2O9, namely, the connectivity of the BO6 polyhedra and atomic displacements occurring purely along the c axis, mean that domain walls preferentially run parallel to the c direction (the polar axis of the material) and thus remain uncharged. The characteristic cloverleaf domain structure reminiscent of the manganites is still present; however, the structure meanders predominantly in the ab plane and, therefore, appears differently depending on the projection direction from which it is viewed. As a result of this microstructural constraint, charged domain walls are not prevalent in this material.

中文翻译：

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不当铁电 CsNbW2O9 中的各向异性曲折域微观结构

不合适的铁电体 CsNbW2O9 最近被强调为锰矿家族之外的第一种材料，它表现出与稀土锰矿中带电畴壁导电增强和减弱的类似蜿蜒六重畴结构。虽然目前没有证据表明 CsNbW2O9 中畴壁传导相对于体积的变化，但微观结构的相似性强烈表明这种材料中存在带电畴壁。在此，我们报告了通过压电响应力显微镜和透射电子显微镜对 CsNbW2O9 域微观结构的综合研究，以揭示实际上这两个系统的域结构存在明显区别。由 CsNbW2O9 的晶体结构引起的约束，即，BO6 多面体的连通性和纯粹沿 c 轴发生的原子位移意味着畴壁优先平行于 c 方向（材料的极轴），因此保持不带电。让人联想到锰矿的特征性三叶草结构域结构仍然存在；然而，该结构主要在 ab 平面内蜿蜒，因此根据观察的投影方向不同，其外观也有所不同。由于这种微观结构的限制，带电畴壁在这种材料中并不普遍。让人联想到锰矿的特征性三叶草结构域结构仍然存在；然而，该结构主要在 ab 平面内弯曲，因此，根据观察的投影方向不同，其外观也有所不同。由于这种微观结构限制，带电畴壁在这种材料中并不普遍。让人联想到锰矿的特征性三叶草结构域结构仍然存在；然而，该结构主要在 ab 平面内蜿蜒，因此根据观察的投影方向不同，其外观也有所不同。由于这种微观结构限制，带电畴壁在这种材料中并不普遍。