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The Verwey transition in nanostructured magnetite produced by a combination of chimie douce and spark plasma sintering J. Appl. Phys. 115, 17E117 (2014) Magnetite nanostructured powder samples were synthesized by aging chemical method. Phase, structural, and magnetic properties were characterized. X-ray diffraction patterns showed cubic magnetite pure phase, with average crystallite size, hDi, equal to 40 nm. Susceptibility measurements showed the well-known Verwey transition at a temperature of 90 K. The decrease of Verwey transition temperature, with respect to the one reported in literature (125 K) was attributed to the low average crystallite size. Moreover, the spin-glass like transition was observed at 35 K. Activation energy calculated from susceptibility curves, with values ranging from 6.26 to 6.93 meV, showed a dependence of spin-glass transition on frequency. Finally, hysteresis loops showed that there is not an effect of Verwey transition on magnetic properties. On the other hand, a large increase of coercivity and remanent magnetization at a temperature between 5 and 50 K confirmed the presence of a magnetic transition at low temperatures. V C 2013 American Institute of Physics.[http://dx

Manganese and Zinc ferrites were prepared by solid state reaction. The resulting powders were pressed into pellets and heat treated at 1100 C. The samples were characterized by using X-ray diffraction, pure phases of zinc ferrite (ZnFe 2 O 4 ) and manganese ferrite (MnFe 2 O 4 ) were obtained. Scanning electron microscopy images showed a good contact between particles. A drop of electrical resistance was found in both samples, MnFe 2 O 4 and ZnFe 2 O 4 , with values going from 2750 to 130 X and from 1100 to 55 X, respectively. Transition temperatures were determined to be T V ¼ 225 K for MnFe 2 O 4 and T V ¼ 130 K for ZnFe 2 O 4 . Magnetoresistance measurements were carried out in the temperature range where R showed the transition, defined as the Verwey-like transition temperature range, DT V . No magnetoresistive effect was observed out of it. The magnetoresistive coefficient (MRC) observed at DT V reached its maximum values of 1.1% for MnFe 2 O 4 and 6.68% for ZnFe 2 O 4 . The differences between MRC values are related to the divalent metal element used. Finally, the magnetoresistive response indicates that the electrical transition observed is strongly influencing the magnetoresistance; where the underlying responsible for this behavior could be a charge reordering occurring at the Verwey-like transition temperature. V C 2014 AIP Publishing LLC. [http://dx