We have studied the dependence versus nominal composition and temperature of the thermal conductivity in the AlCoFeCr system close to the region where an approximant of the decagonal phase forms.this compound of the Al_5Co_2 type shows a melting temperature above 1100 deg C and is of interest because it dispays low thermaal conductivifty whereas its expansion coefficient is comparable to those of metallic substrates.used as a coating,it is of potential value for the sake of producign thermal barriers.from a study of the occupied band by X-ray emission spectroscopy,we show that its poor thermal conductiviyt above room temperature fits with the recurrent localizaiton scheme of electronic states.
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