X-ray photoelectron spectroscopy study on YbFe₂As₂ crystals prepared by different growth temperatures

Polycrystalline samples of YbFe2As2 were synthesized by double step solid-state reaction method. Two different samples were grown at the temperatures of 900 and 1200 degrees C. The synthesized YbFe2As2 polycrystalline samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and X-ray photoelectron spectroscopy (XPS). SEM images revealed that the YbFe2As2 compound was formed as polycrystalline with typical sizes of granules ranging from 5 to 10 mu m. The Rietveld refinement of the XRD data of YbFe2As2 crystals was performed to understand the structural phase. The oxygen adsorption in to the surface of YbFe2As2 crystals was studied by means of XPS analysis. A possible explanation was given for the synthesis temperature dependent oxygen adsorption in to the YbFe2As2 based on the results of XPS, EDAX and resistance versus temperature measurements.