The significant role of the rare earth ions on the elastic and thermodynamic parameters of LiCoDy- and ZnCoCe-ferrites

Two types of rare earth ferrites [Li0.6Co0.1DyxFe2.3−xO4; 0.0⩽x⩽0.2] and [Zn0.5Co0.5CeyFe2−yO4; 0.0⩽y⩽0.2] were prepared by standard ceramic technique with a view to investigate their elastic behavior and some essential thermodynamic parameters. The elastic properties were studied by measuring the ultrasonic velocities by adopting the pulse transmission technique. Longitudinal (VL) and shear (VS) velocities, Young's modulus (E), Debye temperature (θD) and specific heat capacity (Cv) have been evaluated for all the investigated samples. The rare earth content as well as its ionic radius plays a significant role in the evaluated parameters. According to the experimental results, the two investigated types of rare earth ferrite are considered as insulator magnetic solids. It was found that for each composition there exists a characteristic temperature, down to which the resonance frequency of the investigated samples drops smoothly, but above this temperature the resonance frequency stays constant. Accordingly, these samples seem to be of importance in industrial applications especially in the field of electronics.