On the Magnetic Behavior of Polycrystalline Single-Phase YBaCo sub(4)O sub(7+ delta )Obtained by Soft Chemical Synthesis

• Published in: Journal of superconductivity and novel magnetism Vol. 27; no. 6; pp. 1435 - 1442
• Main Authors: Vallejos, E, Galeano, V, Gomez, L, Mera, J, Cordoba, C, Gomez, A, Paucar, C, Moran, O
• Format: Journal Article
• Language: English
• Published: 01-06-2014
• Subjects: Antiferromagnetism; COPPER OXIDE; CRYSTAL STRUCTURE; Ferromagnetism; Filing; LATTICE PARAMETERS; MAGNETIC PROPERTIES; Magnetization; Magnetization curves; MICA; PHASES; Single crystals; Stemming; SUPERCONDUCTORS; X RAY DIFFRACTION; YTTRIUM OXIDE
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-014-2481-8

Polycrystalline single-phase YBaCo sub(4)O sub(7+ delta )samples were synthesized by a wet chemistry method based on the so-called citrates route. The structural, morphological, and magnetic properties of the so-obtained samples were carefully studied by standard experimental techniques. The X-ray powder diffraction (XRD) patterns showed reflections of a pure hexagonal structure (space group P6 sub(3)mc) with lattice parameters being very close to those reported in the literature. No evidence of affectation by any secondary phase such as 112 (YBaCo sub(2)O sub(5.5)) was provided by XRD analysis. This finding was further corroborated by sensible SQUID magnetic measurements which showed signals stemming merely from the desired 114 phase (YBaCo sub(4)O sub(7+ delta )). A bifurcation in the zero field-cooled (ZFC) and FC magnetization curves below similar to 80 K was observed. The M sub(ZFC)(T) curve displays a sharp peak at similar to 70 K and continues to be different down to the lowest temperature. In turn, the M sub(FC)(T) curve shows a sharp rise at similar to 80 K and peaks at similar to 50 K. The conspicuous increase in the magnetization observed at similar to 80 K seems to be correlated with a transition into a long-range ordered antiferromagnetic state. This magnetic behavior is consistent with that observed in YBaCo sub(4)O sub(7+ delta )single crystals. In turn, isothermal magnetization recorded at 70 K showed field-induced effects manifested itself in the appearance of a ferromagnetic component which could be originated by spin canting of the underlying antiferromagnetic state. The possible spin-glass behavior of the studied samples is ruled out through measurements of the real part of the AC susceptibility as a function of the frequency (8-473 Hz) on YBaCo sub(4)O sub(7+ delta )single-crystals. Beyond this relevant result, the collected data demonstrate that the tested chemical route emerges as a suitable alternative to synthesize complex single-phase oxides such as the YBaCo sub(4)O sub(7+ delta )cobaltate.