| Summary: | This thesis describes the synthesis and characterisation of phases related to schafarzikite (FeSb\(_2\)0\(_4\)). A range of Co\(_1\)\(_-\)\(_x\)Fe\(_x\)Sb\(_2\)\(_-\)\(_y\)Pb\(_y\)O\(_4\) (where x = 0, 0.25, 0.50 and 0.75; y = 0-0.75) compounds have been synthesised and characterised by a variety of techniques e.g. neutron powder diffraction (NPD), and thermogravimetric analysis. The refined lattice parameters for all compounds range between a = 8.4492(2) Å - 8.5728(2) Å and c = 5.9170(1) Å - 6.0546(2) Å (NPD, 300 K). The magnetic structures of Co\(_0\)\(_.\)\(_2\)\(_5\)Fe\(_0\)\(_.\)\(_7\)\(_5\)Sb\(_2\)O\(_4\) and Co\(_0\)\(_.\)\(_5\)\(_0\)Fe\(0\)\(_.\)\(_5\)\(_0\)Sb\(_2\)O\(_4\) have been shown to possess dominant A- type ordering as a result of overriding direct exchange interactions between intrachain transition metal cations, whilst all other phases show dominant C- type ordering consistent with 90˚ superexchange. Unusual negative susceptibility is seen and explained in several samples including CoSb\(_2\)O\(_4\). All phases are shown to display canted antiferromagnetic magnetic order. Oxidised intermediates are formed and characterised for the first time. This has been critically linked to the presence of Fe\(^2\)\(^+\) within these phases. There is evidence to suggest the excess oxygen is a peroxide and/or superoxide species. The synthesis of LiSbO\(_2\) is described and its structure determined: P2\(_1\)\(_/\)\(_c\) symmetry with a = 4.8550(3) Å, b = 17.857(1) Å, c = 5.5771(4) Å, β = 90.061(6)˚. Its electrical and thermal properties are described.
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