Magnetization Properties Study of ${\rm ZnCr}_{2}{\rm O}_{4}$ Spinel Normal

The magnetic properties and crystal structure of Zn chromite spinel normal have been investigated by dc/ac magnetization as a function of temperature and magnetic field. In addition, X-ray powder diffraction and scanning electron microscopy measurements were carried out at room temperature. The structural refinement was performed by means of the Rietveld method and the lattice parameter calculated for this material is 8.327 Å, consistent with those reported for the bulk materials in the literature. The average sizes of the particles were calculated from the Scherrer´s equation and compared with the size obtained by scanning electron microscopy. We noticed an increase in the average size of particles with increasing calcination temperature. However, ZnCr₂O₄ nanoparticles with grain sizes of about 10-15 nm presents an effective moment of 3.90 μB/Cr³⁺, value slightly higher than expected 3.8 μB/f.u., for free ion Cr³⁺, and a Curie-Weiss temperature of -290 K which implies that this system is geometrically frustrated.