Analysis of quadrupole splitting of transition metal doped /spl beta/-FeSi2

Large quadrupole splittings (Q.S.) are observed in Co doped specimen, compared with other transition metal doped specimens while isomer shifts (I.S.) do not show large value. Since Q.S. is associated with the electric field gradient at nucleus of iron atom; we calculate the potential at nucleus site, assuming the interaction between LA-phonon-conduction electron. Through the calculations, it is found that electric field gradient increase with the number of phonons attached to a conduction electron (=). Accordingly large Q.S. for Co doped specimen are considered to be due to large in comparison with those for other transition metal doped specimen.