Experimental and computational studies of low-dimensional functional materials

Abstract

This thesis describes the synthesis, characterisation and density functional theory investigation of a range of MX$_2$O$_4$ compounds related to Schafarzikite, FeSb$_2$O$_4$. Chemical substitution of the M cation has been performed to yield Mn$_x$Co$_1$$_−$$_x$Sb$_2$O$_4$, which is characterised both structurally and magnetically. Additionally, the synthesis and magnetic behaviour of the mineral Trippkeite (CuAs$_2$O$_4$ has been investigated. Density functional theory calculations have been performed for a wide range of MX$_2$O$_4$ compounds, both to investigate structural behaviour at high pressure, and also to rationalise the experimentally observed magnetic order. In addition, the technique has been used to predict the magnetic groundstate of CuAs$_2$O$_4$, before an experimental validation. The structurally-related compounds Versiliaite and Apuanite have been synthesised for the first time, and characterised both structurally and magnetically. Their relation to the Schafarzikite structure is discussed, as are the differences in magnetic ordering