Non-equilibrium cation influence on the Néel temperature in ZnFe2O4

Oxygen-vacancy-induced local ferromagnetism as a driving mechanism in enhancing the magnetic response of ferrites

“…1). Furthermore, the same x B /x A for 2ZF10H and BZF10H is consistent with their quite similar magnetic response, microstructure, and configuration of cations [11,39]. From the theoretical point of view, the AFM local rearrangement of case II also appeared energetically favorable [see Table II (S2)].…”

Effect of Thermal Treatment at Inert Atmosphere on Structural and Magnetic Properties of Non-stoichiometric Zinc Ferrite Nanoparticles

“…When the particle size decreases, the composition of ZF is altered, leading to the occurrence of superparamagnetism or ferrimagnetism at room temperature. [5,[22][23][24][25][26][27][28][29] This is mainly related to the redistribution of cations in the lattice, which occurs when grain sizes are decreased to nanoscale. [24,[30][31][32] In contrast to bulk ZF (of normal spinel structure), nanoparticles of stoichiometric zinc ferrite (ZF NPs) reveal a mixed spinel structure, where Zn 2+ and Fe 3+ cations are distributed between () Td and [] Oh sites.…”

Magnetic Phase Diagram of Nanostructured Zinc Ferrite as a Function of Inversion Degree δ

“…In this sense, the change from paramagnetic to superparamagnetic or ferrimagnetic behavior at room temperature for nanosized zinc ferrite has been associated to the partial exchange at the spinel lattice between Fe 3+ ions in the octahedral sites and Zn 2+ ions in the tetrahedral sites. [18][19][20] This mixed cation distribution is favored in nanosized zinc ferrite, but comparing magnetic properties of nanoparticles prepared by different synthesis methods, as co-precipitation, 21 sol-gel, 22 hydrothermal route, 23 combustion, 24 forced hydrolysis in a polyol medium, 25 mechanochemical synthesis, [26][27][28][29] among others, it can be concluded that they depend not only on the particle size but also on the synthesis method. Whereas ZnFe2O4 in bulk shows antiferromagnetic (AFM) to paramagnetic (PM) transition at TN  9 K, particles prepared by nonequilibrium processing present a transition to ferromagnetic (FiM) or ferromagnetic (FM) ordering at significantly higher temperatures: around 30 K for the coprecipitation 30 and the solgel methods 31 , above 77 K for the ball-milled nanoparticles, 32 , or near room temperature in thin film prepared by a sputtering method.…”

“…Traditionally, zinc ferrites have been used mainly as a synthetic inorganic pigment for coloring plastics and rubber and for preparing highly corrosion-resistant organic coating systems, and, in recent years, the attention has been paid on different applications like gas sensors, photocatalytic disinfection, or photocatalytic degradation of different chemical species. − In addition, an interesting property of this material is the possibility to tune its magnetic behavior by varying the particle and/or crystallite size. In this sense, the change from paramagnetic (PM) to superparamagnetic or ferrimagnetic (FiM) behavior at room temperature for nanosized zinc ferrite has been associated with the partial exchange at the spinel lattice between Fe 3+ ions in the octahedral sites and Zn 2+ ions in the tetrahedral sites. − This mixed cation distribution is favored in nanosized zinc ferrites, but comparing magnetic properties of nanoparticles prepared by different synthesis methods, such as coprecipitation, sol–gel, hydrothermal routes, combustion, forced hydrolysis in a polyol medium, mechanochemical synthesis, − among others, it can be concluded that they depend not only on the particle size but also on the synthesis method. Whereas ZnFe 2 O 4 in bulk shows antiferromagnetic (AFM) to paramagnetic (PM) transition at T N ≈ 9 K, particles prepared by nonequilibrium processing present a transition to ferrimagnetic (FiM) or ferromagnetic (FM) ordering at significantly higher temperatures: around 30 K for the coprecipitation and the sol–gel methods, above 77 K for the ball-milled nanoparticles, or near room temperature in thin films prepared by a sputtering method …”