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High temperature structural transformations in NiCr2S4 have been investigated by neutron powder diffraction in situ. At 835(5) °C, NiCr2S4 undergoes an order–disorder transition from the monoclinic Cr3S4 structure to a hexagonal cation-deficient NiAs structure. Above the transition temperature, cation vacancies, which at room temperature are ordered in every second cation layer, become statistically distributed between all cation layers. Prior to this structural transition, intralayer disordering of vacancies occurs within the half-occupied layer. This is not sufficiently complete to cause the change to trigonal symmetry which has been reported for binary sulfides.

A combination of time-of-flight powder neutron diffraction and powder X-ray diffraction has been used to investigate changes in the cation distribution in a series of isostructural (space group I2/m a≈5.9, b≈3.3 c≈11.3Å, β≈92°) ternary vanadium sulfides, AV2S4 (A=Ti, Cr, Fe, Ni). A progressive change from an inverse Cr3S4 structure, when A is drawn from the left of the transition series, to a normal Cr3S4 structure, when A is drawn from the right of the series, occurs. The magnetic susceptibility of all materials has a significant temperature-independent component and both spin-glass behaviour [A=Cr, Tg=15(3) K] and long-range magnetic order [A=Fe, TN=135(3) K] are observed.

Time-of-flight powder neutron diffraction has been used to investigate the distribution of nickel and chromium cations between two crystallographically independent sites in the series of ternary sulfides, NixCr3–xS4 (0

Materials of nominal composition La1–xPbxMnO3 (0.0≤x≤0.4) prepared by prolonged annealing at 950 °C, have been characterised by a combination of powder X-ray diffraction, energy dispersive X-ray microanalysis, thermogravimetry, atomic absorption spectroscopy and oxidising-power analysis. All phases adopt a rhombohedral variant of the perovskite structure and show significant deviations from nominal stoichiometries. All doped materials exhibit ferromagnetic ordering at a temperature, TC , close to ambient and undergo a metal–insulator transition at a temperature, TMI , close to TC . Both TC and TMI show greater compositional variation than previously reported.