Evidence for the First Misfit Layer Oxide Tl0.41(Sr0.9O)1.12CoO2.

A misfit layer oxide Tl0.41(Sr0.9O)1.12CoO2 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 S1 (a = 4.9498(5) A, b1 = 5.0222(6) A, c = 11.656(1) A, β = 97.755(7)°) characterizes the strontium-deficient rock-salt layers [(Sr0.9□0.1)O]∞, whereas the subsystem S2 (a = 4.9498(5) A, b2 = 2.807(2) A, c = 11.656(1) A, β = 97.755(7)°) corresponds to the octahedral [CoO2]∞ layers that exhibit the CdI2 structure. The thallium atoms are located between the two kinds of layers, with a distorded tetrahedral coordination, ensuring the cohesion of the structure.