Thermally induced structural modification in Pt/C X-ray multilayer mirrors fabricated by electron beam evaporation

Platinum-carbon multilayer mirrors with a bilayer spacing of 50 A were fabricated in an ultrahigh vacuum electron beam evaporator. The thermal stability of these multilayers was studied under vacuum annealing using X-ray reflectivity and X-ray diffraction. Up to 450°C, the bilayer spacing increases monotonically accompanied by a gradual increase in crystallite size and grain texture. At 500°C multilayer reflection vanishes, platinum crystallites grow abruptly, and there is a strong texture of platinum in the [220] -plane. Possible reasons for thermally induced structural modifications in these multilayers are discussed.