Oxygen-vacancy-formation enthalpy in YBa2(Cu0.985Fe0.015)3O7−δ oxide superconductor

Chuck Blue; Khaled Elgaid; Ivan Zitkovsky; P. Boolchand; Darl McDaniel; W. C. H. Joiner; Jean Oostens; Warren Huff

doi:10.1103/PhysRevB.37.5905

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Oxygen-vacancy-formation enthalpy in YBa2(Cu0.985Fe0.015)3O7−δ oxide superconductor

Chuck Blue, Khaled Elgaid, Ivan Zitkovsky, P. Boolchand, Darl McDaniel, W. C. H. Joiner, Jean Oostens, Warren Huff

DOI 10.1103/PhysRevB.37.5905 · Physical Review B

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Abstract

Fe57 Mossbauer spectra of YBa2(Cu0.985Fe0.015)3O7−δ samples display multiple sites (n=A, B, C, and D) with the site intensity ratios In/I exhibiting profound thermal annealing effects in the temperature range 150 °C<Ta<550 °C associated with oxygen desorption. Specifically, the ratio IA/I is a function of Ta, and displays an activation enthalpy of site formation ΔHA=104(3) meV. We ascribe it to the filling of O(1) oxygen vacancy sites in chains. The miniscule ΔHA is probably the consequence of the under-coordinated nature of the orthorhombic structure which globally promotes a superelastic (soft) lattice.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YBa2(Cu0.985Fe0.015)3O7-δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	88.6	Pressure not reported	midpoint
YBa2Cu3O7-δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	95	Pressure not reported	unknown