Fig. 1: Crystal structure of pseudo-trigonal Cu4(OH)6Cl2 in comparison with Clinoatacamite.
a Structure of pseudo-trigonal Cu4(OH)6Cl2 viewed along the [111] direction with the revealed magnetic structure at 1 K illustrated in (b). Cu ions are present in blue, O in red, H bonded to O in pearl white, and Cl in green. The (111) lattice plane forms a Kagome layer. The numbers on Cu correspond to the crystallographic sites as indicated in Table 1. The Cu ions in sites of 3A, 3B, 3C, 4A, 4B, and 4C form a Kagome layer with inter-Kagome-layer Cu1A, Cu2A, Cu2B and Cu2C. Only the Cu ions within the Kagome layers are bonded by a single Cu-O-Cu bonding. c Similar Kagome layer in the (101) lattice plane in Clinoatacamite (7), wherein only the atoms near the Kagome layer are shown. All triangles in the Kagome layer consist of one Cu1 and two Cu3 ions, with distances of Cu1-Cu3 = 3.4015(3) Å, 3.4204(3) Å; Cu3-Cu3 = 3.4037(5) Å.
