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Updated: Sep 9, 2026
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Interrelationship between cation inversion and structural, morphological, optical, and magnetic properties in
Yasmeen Gull1, Hilal Ahmad Dar2, Lila Alkhtaby3
1Department of Physics, Government Degree College Pulwama Jammu and Kashmir PIN 192301 India.
Abstract:
Cation inversion critically governs magnetic exchange in spinel ferrites, yet it is typically treated as a fixed structural form rather than a tunable variable. In this work, we show that Ni2+ substitution in magnesium ferrite, forming the isovalent solid-solution series Mg1-x Ni x Fe2O4 (x = 0.0, 0.1, 0.3, 0.5), drives a thermodynamically controlled redistribution of cations between the tetrahedral and octahedral sublattices, which in turn governs the evolution of the saturation magnetisation and coercivity across the series. Structural characterisation via X-ray diffraction, Fourier-transform infrared spectroscopy and Raman spectroscopy confirms a single-phase cubic spinel, while UV-visible diffuse reflectance spectroscopy, vibrating sample magnetometry, and scanning electron microscopy provide complementary insight into optical, magnetic, and morphological properties, respectively. We introduce a thermodynamic framework based on a free-energy functional that incorporates exchange interactions, crystal-field effects, and configurational entropy. Within this model, the inversion parameter arises as an equilibrium order parameter determined by free-energy minimisation. This work reframes cation inversion as a controllable thermodynamic degree of freedom, offering new pathways for the rational design of functional spinel ferrites.
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