THERMOELECTRIC-POWER IN GD3-SUBSTITUTED CU-CD FERRITES()

Polycrystalline CdxCu1-xFe2-yGdyO4 ferrites for y = 0.0 and 0.1 were p repared by ceramic technique. X-ray diffractograms of powder samples s how cubic symmetry with x greater than or equal to 0.2 for y = 0.0 and 0.1, while compositions with x = 0.0 for y = 0.0 and 0.1 are tetragon al. The thermopower measurements for Gd3+-undoped ferrites in the temp erature range 300 K to 788 K show n-type conductivity for x greater th an or equal to 0.2. The substitution of Gd3+ changed n-type conductivi ty of the compositions to p-type. The mobilities calculated show decre asing trend on Gd3+ substitution. The values of activation energy Delt a E and drift mobility E(d) suggest polaron formation in substituted s amples. The conduction mechanism is explained on the basis of localize d model and formation of Gd3+ + Fe2+ stable pairs at B site and Cu1+ Fe3+ at A site.