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2. Structural Characterization and Magnetic Behavior Due to the Cationic Substitution of Lanthanides on Ferrite Nanoparticles.

Author

Pinto García, Cristóbal, Maine, Arianne, Valenzuela-Fernández, Rodrigo A., Aliaga Cerón, Álvaro, Barahona Huenchumil, Patricia, Peña, Octavio, Álvarez-Serrano, Inmaculada, Ibáñez, Andrés, Melo, Francisco, and Galdámez Silva, Antonio

Subjects
NICKEL ferrite, RARE earth metals, FERRITES, MAGNETIC measurements, TRANSMISSION electron microscopy, RIETVELD refinement, NANOPARTICLES
Abstract

A new series of [Fe3−xLnx]O4 nanoparticles, with Ln = Gd; Dy; Lu and x = 0.05; 0.1; 0.15, was synthesized using the coprecipitation method. Analyses by X-ray diffraction (XRD), Rietveld refinement, and high-resolution transmission electron microscopy (HRTEM) indicate that all phases crystallized in space group F d 3 ¯ m , characteristic of spinels. The XRD patterns, HRTEM, scanning electron microscopy analysis (SEM-EDS), and Raman spectra showed single phases. Transmission electron microscopy (TEM), Rietveld analysis, and Scherrer's calculations confirm that these materials are nanoparticles with sizes in the range of ~6 nm to ~13 nm. Magnetic measurements reveal that the saturation magnetization (Ms) of the as-prepared ferrites increases with lanthanide chemical substitution (x), while the coercivity (Hc) has low values. The Raman analysis confirms that the compounds are ferrites and the Ms behavior can be explained by the relationship between the areas of the signals. The magnetic measurements indicate superparamagnetic behavior. The blocking temperatures (TB) were estimated from ZFC-FC measurements, and the use of the Néel equation enabled the magnetic anisotropy to be estimated. [ABSTRACT FROM AUTHOR]

Published
2024
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50. μ-BENZENE-1,2,4,5-TETRACARBOXYLATO-κ2O1:O4)BIS-[AQUA-BIS-2-(AMINOMETHYL) PYRIDINE-κ2N,N’) NICKEL (II)] DECAHYDRATE: STRUCTURE AND MAGNETIC PROPERTIES

Author

Atria, Ana María, Parada, José, Baggio, Ricardo, Peña, Octavio, and Moreno, Yanko

Subjects
crystal structure, magnetism, nickel complex
Abstract

μ-Benzene-1,2,4,5-tetracarboxylato-κ2O1:O4)bis-[aqua-bis-2-(aminomethyl) pyridine-κ2N,N’) nickel (II)] decahydrate, [Ni2(amp)4(btc)(H2O)2]10H2O has been synthesized and its crystal structure determined by X-ray diffraction. The complex crystallizes in the Monoclinic space group P21/n with cell dimensions a= 11.0102 (10) Å, b= 21.5416 (19) Å, c= 11.0445 (10) Å and β= 118.753 (1)°, and two formula units per cell (Z= 2, Z’= 0.5). The structure consists of centrosymmetric dimeric units in which the benzene tetracarboxylate anions (btc) bridge the symmetry-related nickel (II) cations, two bidentate chelating molecules of 2-(aminomethyl) pyridine and a terminal aqua ligand completing the six-fold coordination at each metal. These dimers link to each other via H-bonding to form chains parallel to [100], while the water solvates form a strongly bound 2D network parallel to (100), made up by small (R44(8)) and large (R2020(40)) rings, the latter ones “pierced” by the chains of dimmers, with a profuse H-bonding interconnection between both substructures. Magnetic susceptibility measurements as a function of temperature disclose weak interdimeric exchange interactions. Fitting of these data to a dimeric model yields J= −3.5 cm-1 and g= 2.13.

Published
2019

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