Effect of Ge4+ substitution in lithium ferrites

X-ray diffraction, infrared, and Mossbauer spectroscopy techniques are used to investigate Li_0.5+0.5xGe_xFe_2.5-1.5xO₄; x ≤ 0.5. The polycrystalline samples show single-phase spinel structure. The lattice constant for x ≥ 0.2 is found to be nearly constant, but smaller than for x = 0. A small component of Fe²⁺ has been detected in the IR spectra. The Mossbauer absorption patterns give magnetic sextets superimposed on a paramagnetic component that increases with increasing germanium content. The average hyperfine field at the A-site is found to decrease faster than at the B-site. A consistent interpretation of the information obtained from the different methods is provided. It is also suggested to give a qualitative explanation for the differential variation of the average hyperfine fields at the two sites on the basis of supertransferred hyperfine interactions.