Aging effect in CaLaBa{Cu1 − xFex}3O7 − δ with 0 ≤ x ≤ 0.07 studied by Mössbauer spectroscopy

Abstract

In this work, we study the long-term aging effect caused by Fe atoms in the superconductor CaLaBa{Cu 1−x Fe x } 3 O 7−δ with 0 ≤ x ≤ 0.07. XRD confirms that this system has a YBCO-like structure. The critical temperature (T c ) is strongly affected by aging and depends on the amount of Fe in the structure. Room temperature Mössbauer spectroscopy reveals the presence of the typical species A, B-B , C and new species E and F. Interestingly; A, which corresponds to the Fe 3+ atom located in the Cu(1) of the chains with spin S z = 3/2, shows a drastic reduction which means migration to the species B, B and C. Species B and B correspond to the Fe 3+ in the Cu(2) site forming planar quasi-octahedral and planar square pyramidal, while the C specie is a square pyramidal with O(5) respectively (spin S z = 3/2 in all these cases). Aging causes loss of superconductivity in the samples with 5 and 7% of iron content.

Mössbauer and differential thermal analysis studies of iron alkali lead-phosphate glasses

“…Moreover, the existence of Fe 2+ in fivefold and sixfold coordination was confirmed previously by a neutron diffraction study [30]. On the other hand, the existence of both Fe 2+ and Fe 3+ in fivefold coordination (bipyramidal coordination) are observed in phosphate glass and some iron minerals [24,[44][45][46][47][48][49][50].…”

Visión retrospectiva de los 14 primeros años de investigación en materiales óxidos cerámicos superconductores en la UNMSM

“…Los resultados obtenidos en este periodo de investigación son publicados en la Revista de Investigación de Física de la UNMSM [44], en la Revista Peruana de Química e Ing. Química de la UNMSM [45][46][47], en la revista de la Sociedad Química del Perú [9,14,[48][49][50], en el Advances in Science and Technology [16], en el Journal of Physics and Chemistry of Solids [51,52], en el Open Journal of Superconductivity [53], en el Japanese Journal of Applied Physics [39] y en el Hyperfine Interactions [54] La investigación de materiales superconductores es una disciplina que requiere de proyectos financiados para poder solventar no sólo la compra de los materiales precursores sino las medidas de caracterización en costosos equipos y para el acceso a la información de trabajos de otros investigadores. Por citar un par de ejemplos, una medida de la susceptibilidad magnética de una muestra de 100 mg en el rango de temperatura de 5 a 100 K usando un magnetómetro con sensor SQUID cuesta aproximadamente 300 Nuevos Soles, 75 euros; el acceso a la literatura científica, significa un costo elevado, medio millón de dólares americanos por año en suscripciones a revistas de investigación.…”

Aging and Environmental Effects on the Superconductor $$\left[{{\text{Y}}}_{1\;-\;x}{{\text{Ca}}}_{x}\right]{{\text{SrBaCu}}}_{2.80}{\left({{\text{BO}}}_{3}\right)}_{0.20}{{\text{O}}}_{y}$$ with $$0.10\;\le\;x\;\le\;0.50$$

“…Currently, among the various limitations to be solved during the development of superconducting materials, there are still pendant tasks to overcome such as achieving temporal stability of superconductivity behavior at several experimental conditions [1], getting vortex creep [2], and avoiding the aging effect and environmental degradation [3][4][5][6][7]. In particular, it is well known that the superconductivity property of cuprate superconductors degrades or destroys with time [8].…”