Evidence for the First Misfit Layer Oxide Tl_0.41(Sr_0.9O)_1.12CoO₂

A misfit layer oxide Tl 0.41 (Sr 0.9 O) 1.12 CoO 2 has been synthesized, and its structural model established by ED and HREM. The cell parameters of the two subsystems have been refined from XRPD data. The subsystem S 1 ( a = 4.9498(5) Å, b 1 = 5.0222(6) Å, c = 11.656(1) Å, β = 97.755(7)°) characterizes the strontium-deficient rock-salt layers [(Sr 0.9 □ 0.1 )O] ∞, whereas the subsystem S 2 ( a = 4.9498(5) Å, b 2 = 2.807(2) Å, c = 11.656(1) Å, β = 97.755(7)°) corresponds to the octahedral [CoO 2 ] ∞ layers that exhibit the CdI 2 structure. The thallium atoms are located between the two kinds of layers, with a distorded tetrahedral coordination, ensuring the cohesion of the structure.