paper

Synthesis-Dependent Properties of Barlowite and Zn-Substituted Barlowite

arXiv:1808.06566 · doi:10.1016/j.jssc.2018.08.016

Abstract

The mineral barlowite, Cu $_{4}$ (OH) $_{6}$ FBr, has been the focus of recent attention due to the possibility of substituting the interlayer Cu $^{2 +}$ 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 (Cu $_{3}$ Zn $_{x}$ Cu $_{1 - x}$ (OH) $_{6}$ FBr). 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.

9 pages, 4 figures. Accepted to the Journal of Solid State Chemistry