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 °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 μm. 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.