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High-Pressure Synthesis of A2NiO2Ag2Se2 (A=Sr, Ba) with a High-Spin Ni2+ in Square-Planar Coordination



Yuki Matsumoto, Takafumi Yamamoto, Kousuke Nakano, Hiroshi Takatsu, Taito Murakami, Kenta Hongo, Ryo Maezono, Hiraku Ogino, Dongjoon Song, Craig Brown, Tassel Cedric, Hiroshi Kageyama


Square-planar coordinate Ni2+ ions in oxides are exclusively limited to a low spin state (S = 0) owing to extensive crystal field splitting. Here we report layered oxychalcogenides A2NiO2Ag2Se2 (A = Sr, Ba) with the S = 1 NiO2 square lattice. The structural analysis revealed that the Ni2+ ion is underbonded by a significant tensile strain from neighboring Ag2Se2 layers, leading to a reduction of the crystal field energy. Ba2NiO2Ag2Se2 exhibits a G-type spin order at 130 K, indicating fairly strong in-plan interactions. The high-pressure synthesis employed here possibly assists the expansion of NiO2 square lattice by taking the advantage of a difference in compressibility in oxide and selenide layers.
Angewandte Chemie-International Edition


neutron diffraction, high pressure synthesis, X-ray diffraction


Matsumoto, Y. , Yamamoto, T. , Nakano, K. , Takatsu, H. , Murakami, T. , Hongo, K. , Maezono, R. , Ogino, H. , Song, D. , Brown, C. , Cedric, T. and Kageyama, H. (2019), High-Pressure Synthesis of A<sub>2</sub>NiO<sub>2</sub>Ag<sub>2</sub>Se<sub>2</sub> (A=Sr, Ba) with a High-Spin Ni<sup>2+</sup> in Square-Planar Coordination, Angewandte Chemie-International Edition, [online], (Accessed June 14, 2024)


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Created January 13, 2019, Updated October 12, 2021