"Synthesis-dependent properties of barlowite and Zn-substituted barlowite"

Rebecca W. Smaha : Wei He, John P. Sheckelton, Jiajia Wen, Young S. Lee; Journal of Solid State Chemistry, 08/18/18.

Additional Authors: Wei He, John P. Sheckelton, Jiajia Wen, Young S. Lee

Abstract:

The mineral barlowite, Cu4(OH)6FBr, has been the focus of recent attention due to the possibility of substituting the interlayer Cu2+ site with non-magnetic ions to develop new quantum spin liquid materials. We re-examine previous methods of synthesizing barlowite and describe a novel hydrothermal synthesis method that produces large single crystals of barlowite and Zn-substituted barlowite (Cu3ZnxCu1–x(OH)6FBr). The two synthesis techniques yield barlowite with indistinguishable crystal structures and spectroscopic properties at room temperature; however, the magnetic ordering temperatures differ by 4 K, and the thermodynamic properties are clearly different. The dependence of properties upon synthetic conditions implies that the defect chemistry of barlowite and related materials is complex and significant. Zn-substituted barlowite exhibits a lack of magnetic order down to T = 2 K, characteristic of a quantum spin liquid, and we provide a synthetic route towards producing large crystals suitable for neutron scattering.