STRUCTURAL DISORDER IN THE ORDERED BETA-E LECTRON COMPOUND AGMG

On the Mg-rich side of the beta-electron compound AgMg structural vaca ncies have been detected at room temperature by comparison of high-pre cision pycnometric and x-ray density measurements, contrary to an earl iar investigation. In addition to the vacancies, Mg antistructure atom s are formed in the Ag sublattice. Above 50,5 at.% Mg both together ke ep the concentration of valence electrons constant and thus inhibit a rise of the Fermi energy caused by additional alloying of Mg if we ass ume a charge -e at a vacancy and +3e at a Mg antistructure atom. The r esults are compared with other beta-electron compounds.