Local vibrations in FCC crystals with two-parametric substitutional impurities

The threshold parameters of defects (the mass defect and the relative chang e in the force constants) are determined at which local vibrations start to occur in an fcc crystal with substitutional impurities. The characteristic s of local vibrations are investigated, and the influence of the defect par ameters on the frequency of local vibrations and their decay rate with dist ance from the impurity atom is analyzed. The frequencies and the intensitie s of local vibrations are calculated for the nearest neighboring atoms of a n impurity, which, combined with the impurity atom, form a defect cluster. (C) 2000 MAIK "Nauka/Interperiodica".