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Ca_25Co_22O_56(OH)_28: a layered misfit compound

T. Klimczuk·H. W. Zandbergen·N. M. van der Pers·L. Viciu·V. L. Miller·M. -H. Lee·R. J. Cava
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Abstract

The high pressure synthesis, structure and magnetic properties of Ca_25Co_22O_56(OH)_28 are reported. The compound has a misfit structure, consisting of double, square calcium oxide hydroxide rock-salt-like layers between hexagonal CoO_2 layers. The misfit compound crystallizes in the monoclinic space group C2/m, and can be characterized by the coexistence of two subsystems with common a=4.893(5)A, c=8.825(9)A and b=95.745(8) parameters, and different b parameters: b_RS=4.894(5)A, and b_HEX=2.809(3)A, for the rock-salt and hexagonal type planes respectively. The compound shows Curie-Weiss paramagnetism with an antiferromagnetic Weiss temperature of -43K and a reduced Co moment. Substantial deviations from Curie-Weiss behavior are seen below 50K with no indication of magnetic ordering. No superconductivity was observed down to a temperature of 2K.

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T. Klimczuk, H. W. Zandbergen, N. M. van der Pers, L. Viciu, V. L. Miller, M. -H. Lee, R. J. Cava. 2005-10-10. Ca_25Co_22O_56(OH)_28: a layered misfit compound. https://arxiv.org/abs/cond-mat/0510137

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