Temperature-Independent, Large Dielectric Constant Induced by Vacancy and Partial Anion Order in the Oxyfluoride Pyrochlore Pb2Ti2O6－δF2δ
Temperature-Independent, Large Dielectric Constant Induced by Vacancy and Partial Anion Order in the Oxyfluoride Pyrochlore Pb2Ti2O6－δF2δ
复制标题
氟氧烧绿石Pb2Ti2O6－δF2δ中空位和部分阴离子有序引起的与温度无关的大介电常数
DOI：
10.1021/acs.chemmater.6b02509
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发表时间：
2016
影响因子：
8.6
通讯作者：
and Katsuyoshi Oh-ishi
中科院分区：
文献类型：
--
作者：
Kengo Oka;Hajime Hojo;Masaki Azuma;and Katsuyoshi Oh-ishi
在混合阴离子体系中，部分阴离子有序可以是实现增强的介电性质的关键。采用固相反应法合成了一种新型A2 B2 X6 X ′0.5型氟氧烧绿石Pb2Ti2O5.4F1.2。同步辐射X射线衍射和电子衍射结果表明，氧氟烧绿石的X位存在部分O2-/F-有序结构，其中F-以界面型Ti（O/F）6配位，与X′位的O2-/空位有序结构相关联.虽然Pb2Ti2O5.4F1.2具有中心对称结构，但精细的占位因子表明存在局域极化。部分O2-/F-阴离子有序稳定了Ti4+的大位移，导致高介电常数（高达800）和低温度系数。这些结果表明，混合杂阴离子的辉石提供了一个基础，探索新的介电材料。
In mixed-anion systems, partial anion order can be the key to realizing enhanced dielectric properties. A novel A2B2X6X′0.5-type oxyfluoride pyrochlore, Pb2Ti2O5.4F1.2, was prepared through the conventional solid-state reaction. Characterization of the oxyfluoride pyrochlore by synchrotron X-ray diffraction and electron diffraction revealed the existence of partial O2–/F–order at the X site, in which F–is involved infac-type Ti(O/F)6coordination, associated with the O2–/vacancy order at the X′ site. Although Pb2Ti2O5.4F1.2adopts a centrosymmetric structure, the refined occupancy factors suggested the existence of local polarization. Partial O2–/F–anion order stabilized the large displacement of Ti4+, leading to a high dielectric constant (as high as 800) with a low-temperature coefficient. These results suggest that mixing heteroanions in pyrochlores provides a basis for exploring novel dielectric materials.