X-ray Absorption Fine Structure (XAFS) measurements of the colossal magnetoresistance (CMR) sample La 0.79 Ca 0.21 MnO 3 at high fields indicate a decrease in the width parameter of the pair distribution function, σ, as the applied magnetic field is increased for T near Tc. The change in σ2 from the disordered polaron state varies approximately exponentially with magnetization irrespective of whether the sample magnetization was achieved through a change in temperature or the application of an external magnetic field. This suggests a more universal relationship between local structure and the sample magnetization than was previously indicated.
This review aims to critically assess the use of X-ray techniques, both of a scattering (e.g. X-ray diffraction (XRD), pair distribution function (PDF)) and spectroscopic nature (X-ray absorption spectroscopy (XAFS)), in the study of cobalt-based Fisher–Tropsch synthesis (FTS) catalysts.
The structure and magnetic properties of nano-sized (1.6 to 4.4 nm) ferrihydrite samples are systematically investigated through a combination of X-ray diffraction (XRD), X-ray pair distribution function (PDF), X-ray absorption spectroscopy (XAS) and magnetic analyses.
X-ray spectroscopic and scattering methods applied to the characterisation of cobalt-based Fischer–Tropsch synthesis catalysts