Magnetic structure of the oxygen-deficient perovskite YBaCuFeO[sub 5+[delta]]

Journal Article · Wed Mar 30 04:00:00 EST 1994 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00085a008· OSTI ID:7198359

Mombru, A W; Christides, C; Lappas, A; Prassides, K ^[1]; Pissas, M; Mitros, C; Niarchos, D ^[2]

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1. Univ. of Sussex, Brighton (United Kingdom)
2. Institute of Materials Science, Demokritos, Attiki (Greece)

The magnetic and crystal structures of the oxygen-deficient layered perovskite YBaCuFeO[sub 5+[delta]] have been determined with powder neutron diffraction methods. It crystallizes in the noncentrosymmetric tetragonal space group P4mm with a = 3.870(2) [angstrom] (at room temperature). Structural motifs of corner-sharing severely elongated CuO[sub 5] (Cu-O[sub eq] = 1.936(2) [angstrom], Cu-O[sub ax] = 2.35(9) [angstrom]) and slightly squashed FeO[sub 5] (Fe-O[sub eq] = 2.03(3) [angstrom], Fe-O[sub ax] = 1.82(9) [angstrom]) square pyramids result in a novel lamellar structure with ordered oxygen defects. Local magnetic moments directed perpendicular to the unique axis ([mu] perpendicular to c, [mu] = 2.51(15) [mu][sub B] at room temperature) appear at the Fe[sup 3+] sites at 442.4(5) K. The magnetic unit cell results by doubling the chemical one along all three crystallographic directions (magnetic propagation vector, k = (1/2,1/2,1/2)). Despite the long separation between successive FeO[sub 2] layers ([approximately]7.7 [angstrom]), the magnetic behavior can be successfully described by a three-dimensional Heisenberg spin Hamiltonian with a critical exponent [beta] = 0.366(8). No evidence of ordering of the Cu sublattice is found on cooling to room temperature.

• OSTI ID: 7198359
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 33:7; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

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CHALCOGENIDES
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CRYSTAL STRUCTURE
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YTTRIUM OXIDES