High-Pressure Synthesis of A₂ NiO₂ Ag₂ Se₂ (A=Sr, Ba) with a High-Spin Ni²⁺ in Square-Planar Coordination.

ABSTRACT: Square-planar coordinate Ni²⁺ ions in oxides are exclusively limited to a low-spin state (S=0) owing to extensive crystal field splitting. Layered oxychalcogenides A₂ Ni^II O₂ Ag₂ Se₂ (A=Sr, Ba) with the S=1 NiO₂ square lattice are now reported. The structural analysis revealed that the Ni²⁺ ion is under-bonded by a significant tensile strain from neighboring Ag₂ Se₂ layers, leading to the reduction in crystal field splitting. Ba₂ NiO₂ Ag₂ Se₂ exhibits a G-type spin order at 130 K, indicating fairly strong in-plane interactions. The high-pressure synthesis employed here possibly assists the expansion of NiO₂ square lattice by ta

SUBMITTER: Matsumoto Y 

PROVIDER: S-EPMC6993455 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature