Covalency Competition in the Quadruple Perovskite CdCu3Fe4O12
Covalency Competition in the Quadruple Perovskite CdCu3Fe4O12
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四重钙钛矿 CdCu3Fe4O12 中的共价竞争
DOI：
10.1021/acs.inorgchem.7b01405
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发表时间：
2017
影响因子：
4.6
通讯作者：
and Hidekazu Ikeno
中科院分区：
文献类型：
--
作者：
Ikuya Yamada;Akihiko Takamatsu;Naoaki Hayashi;and Hidekazu Ikeno
镉离子（Cd 2+）的大小与钙离子（Ca 2+）相似，而由于高电负性，Cd 2+离子倾向于与相邻的阴离子形成共价键。共价Cd-O键影响其他金属-氧键，导致晶体结构和电子态的急剧变化。在这里，我们展示了高压合成，晶体结构和性能的一个新的四重钙钛矿CdCu 3Fe 4 O 12。该化合物表现出的电子相变伴随着一个没有电荷有序的铁离子的电荷分离低于200 K，不同于电荷分离转变与岩盐型电荷有序的CaCu 3Fe 4 O 12。第一性原理计算和钼穆斯堡尔谱表明，共价Cd-O键有效地抑制了Fe-O键的共价性，导致了与CaCu 3Fe 4 O 12不同的电子态.这一发现提出了组成金属离子之间的共价竞争主导的复杂金属氧化物的电子状态。
Cadmium ions (Cd2+) are similar to calcium ions (Ca2+) in size, whereas the Cd2+ions tend to form covalent bonds with the neighboring anions because of the high electronegativity. The covalent Cd–O bonds affect other metal–oxygen bonds, inducing drastic changes in crystal structures and electronic states. Herein, we demonstrate high-pressure synthesis, crystal structure, and properties of a new quadruple perovskite CdCu3Fe4O12. This compound exhibits an electronic phase transition accompanying a charge disproportionation of Fe ions without charge ordering below ∼200 K, unlike charge-disproportionation transition with rock-salt-type charge ordering for CaCu3Fe4O12. First-principle calculations and Mössbauer spectroscopy display that covalent Cd–O bonds effectively suppress the Fe–O bond covalency, resulting in an electronic state different from that of CaCu3Fe4O12. This finding proposes covalency competition among constituent metal ions dominating electronic states of complex metal oxides.