X-ray absorption fine-structure study on the Ni(OH)2 monolayer nanoclusters

The local structure around Ni ion for Ni(OH)2 monolayer nanocluster (Ni-MNC) was studied by Ni K-edge X-ray absorption fine-structure spectroscopy (XAFS). XAFS analyses were consistent with the monolayer formation of the nanoclusters. We found that the Ni–Ni distance in the monolayer plane exhibits a significant contraction compared to that in bulk Ni(OH)2, while the spacing between the Ni and O layers are rather expanded. Such a structural change is discussed in relation to the magnetic property of the Ni-MNC, which exhibits ferromagnetism below 10 K with a higher exchange interaction between the in-plane Ni atoms than that of the bulk Ni(OH)2.