Magnetic hyperfine fields in Dy/sub 1-x/Y/sub x/Al/sub 2/

/sup 161/Dy Moessbauer spectroscopy was carried out at 4.2 K on Dy/sub 1-x/Y/sub x/Al/sub 2/ for 0 less than or equal to x less than or equal to 0.6. For x=0 we find B=580 T and f/sub Q/=2810 MHz, close to free-ion values. For x > 0 both B and f/sub Q/ decrease weakly. We obtain (..delta..B)/sub n/ = -14 T, (..delta..f/sub Q/)/sub n/ = -110 MHz and (..delta..B)/sub nn/ = + 1.6 T, (..delta..f/sub Q/)/sub nn/ = +4 MHz per replaced nearest and next-nearest Dy/sup 3 +/ neighbor, respectively.