Elastic properties of germanium substituted lithium ferrite

Polycrystalline ferrites with general formula Li0.5+0.5xGexFe2.5−1.5xO4 (where x = 0.0, 0.1, 0.2, 0.3 and 0.4) were prepared by the standard ceramic technique. The analysis of XRD patterns revealed the formation of single-phase cubic spinel structure. The lattice constant was found to decrease with the increase in germanium content. Infrared spectra were performed at room temperature in the wave number range of 200–1000 cm−1. Two prominent bands were observed; high frequency band ‘υ1’ around 583 cm−1 is assigned to the tetrahedral complexes and low frequency band ‘υ2’ around 392 cm−1 is assigned to the octahedral complexes. Low frequency absorption band ‘υ3’ appeared at 240 cm−1 is assigned to lattice vibrations. Force constant for the tetrahedral and octahedral sites was calculated by using IR data. Elastic moduli such as Young’s modulus (E), bulk modulus (B), modulus of rigidity (G), Poisson ratio (σ) and Debye temperature (θD) were determined. In the present work the elastic moduli increase with germanium content whereas Poisson’s ratio almost remains constant. A linear relationship between Debye temperature and average sound velocity was observed.