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Lakhani V.K.,H And Hb Kotak Institute Of Science | Modi K.B.,Saurashtra University
Solid State Sciences | Year: 2010

Ultrasonic pulse echo-overlap technique at 300 K (9 MHz) has been employed to study the elastic properties of Al3+-substituted CuFe 2O4 spinel ferrite system. The longitudinal and transverse wave velocities are used to compute elastic moduli and these are corrected to the zero porosity by employing different models. Contrary to expectation, the magnitude of elastic moduli is found to decrease by 75% with only 30% of Al 3+-substitution for Fe3+ in the system. The lowering of elastic stiffness is mainly due to residual stress-induced spontaneous cracking and presence of oxygen vacant sites in the material. The lower value of lattice energy for polycrystalline specimens as compared to their single crystalline counterparts have been explained in the light of an increase degree of disorientation at the grain boundary with Al3+-substitution. Source

Dhruv D.,Gujarat Technological University | Trivedi R.K.,H And Hb Kotak Institute Of Science | Nimavat B.,Saurashtra University | Kansara S.,Saurashtra University | And 6 more authors.
AIP Conference Proceedings | Year: 2013

Substitution of monovalent K+ at La3+ in solid state reaction synthesized La1-xKxMnO3(0.0≤x≤0. 3) manganites results in metallic behavior. Increase in K+ content (x ≤ 0.15) enhances the FM interactions through ZDE mechanism while for higher x > 0.15, structural disorder and AFM interactions between Mn4+ ions become prominent. © 2013 American Institute of Physics. Source

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