Crystal-chemical anomalies in nonsuperconducting PrBa[sub 2]Cu[sub 3]O[sub 7]

Conference · Tue Feb 01 00:00:00 EST 1994 · Journal of Superconductivity; (United States)

OSTI ID:7020782

Vanderah, T A; Lowe-Ma, C K ^[1]

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1. Naval Air Warfare Centre Weapons Division, China Lake, CA (United States)

Studies of the crystal chemistry of nonsuperconducting PrBa[sub 2]Cu[sub 3]O[sub 7] indicate that this compound is strictly isostructural with its superconducting RBa[sub 2]Cu[sub 3]O[sub 7] (R - Y, rare earth) analogs. Crystallographically, Pr is present in the trivalent state according to the structural trends exhibited by the RBa[sub 2]Cu[sub 3]O[sub 7] series as a function of R[sup 3+] ionic radius. The sole structural anomaly attributable to the presence of Pr[sup 3+] in the YBa[sub 2]Cu[sub 3]O[sub 7] structure is a next-next-nearest neighbor effect and consists of an unusually short axial Cu-O distance, i.e., a short bond length between the in-plane copper and the chain oxygen. The correlation of this anomaly with the nonmetallic/nonsuperconducting properties of PrBa[sub 2]Cu[sub 3]O[sub 7] supports a variety of literature reports, both theoretical and experimental, suggesting that the apical oxygen in the YBa[sub 2]Cu[sub 3]O[sub 7] structure plays a critical role in mediating the appearance of superconductivity. The mechanism by which the f-electrons in Pr[sup 3+] (f[sup 2]) interact with the Cu-O manifold to produce the nonmetallic behavior of PrBa[sub 2]Cu[sub 3]O[sub 7] remains unknown: however, superconductivity is [open quotes]turned back on[close quotes] for Nd[sup 3+] (f[sup 3]), immediately next to Pr and just slightly smaller. 46 refs., 5 figs.

• OSTI ID: 7020782
• Report Number(s): CONF-930710-; CODEN: JOUSEH
• Journal Information: Journal of Superconductivity; (United States), Vol. 7:1; Conference: Physics and chemistry of molecular and oxide superconductors conference, Eugene, OR (United States), 27-31 Jul 1993; ISSN 0896-1107
• Country of Publication: United States
• Language: English

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HYBRIDIZATION
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