No abstract

Keeping in view the increased usage of orthorhombic materials in the development of advanced engineering materials such as fibers and composites and other multilayered media, the aim of the present paper is to give a detailed account of the plane harmonic generalized thermoelastic waves in orthorhombic materials. According to the frequency equation, the four waves, a quasi-longitudinal, two quasi-transverse, and a quasi-thermal wave, can propagate in an orthorhombic crystal. When plane waves propagate along the axis of an orthorhombic solid, then only the longitudinal and thermal waves are coupled, whereas the transverse waves get decoupled from the rest of the motion. For plane waves propagating in one plane of the solid, only the SH wave in that plane remains purely transverse and gets decoupled from the rest of the motion and vice versa. The other three waves are coupled and get modified due to thermal variations and relaxation time. The particle paths and stability of the waves have been discussed and the results verified numerically. These have been represented graphically for single crystals of solid helium and cobalt material.

No abstract

No abstract

The effect of substitution of nonmagnetic Al 3+ ions on the electrical and magnetic properties of Mg–Mn ferrites was studied in the ferrite series Mg 0.9 Mn 0.1 Al x Fe 2-x O 4 where x varied from 0–0.5 in steps of 0.1. The incorporation of Al 3+ ions in place of Fe 3+ ions results in a decrease of the lattice parameter owing to the smaller size of the substituted ions. The increase in dc resistivity has been observed at the expense of the deterioration of magnetic properties. A significant reduction in the values of the initial permeability, saturation magnetization and Curie temperature has been observed with successive increase of Al 3+ ions. These changes in properties have been explained on the basis of various models and other relevant factors, like modified cation distribution and magnetic interactions. The high dc resistivity, thereby lowering the dielectric losses, and the low value of the saturation magnetization are the desired characteristics of aluminium-substituted Mg–Mn ferrites used to prepare microwave devices operating in L, S and C bands.