THE EFFECT OF GE4+ SUBSTITUTION IN LITHIUM FERRITES

X-ray diffraction, infrared, and Mossbauer spectroscopy techniques are used to investigate Li0.5+0.5xGexFe2.5-1.5xO4; x less than or equal t o 0.5. The polycrystalline samples show single-phase spinel structure. The lattice constant for x greater than or equal to 0.2 is found to b e nearly constant, but smaller than for x = 0. A small component of Fe 2+ has been detected in the IR spectra. The Mossbauer absorption patte rns give magnetic sextets superimposed on a paramagnetic component tha t increases with increasing germanium content. The average hyperfine h eld at the A-site is found to decrease faster than at the B-site. A co nsistent interpretation of the information obtained from the different methods is provided. It is also suggested to give a qualitative expla nation for the differential variation of the average hyperfine fields at the two sites on the basis of supertransferred hyperfine interactio ns.