Anomalous thermal expansion in substituted Nd/sub 2/Fe/sub 17-x/Si/sub x/ and Nd/sub 2/Fe/sub 17-x/Al/sub x/ compounds

The temperature dependencies of the lattice parameters were measured from room temperature to 400/spl deg/C for powders of the substituted compounds Nd/sub 2/Fe/sub 17-x/Al/sub x/ and Nd/sub 2/Fe/sub 17-x/Si/sub x/, x=0,1,2,3, using high-temperature X-ray diffraction. All compounds crystallize in the rhombohedral Th/sub 2/Zn/sub 17/-type structure (space group R.