The 2√2 a0 × √2 b0 × c0 herringbone phase of YBa2Cu3O6 + x. No oxygen ordering but an alien oxide, BaCu3O4

Oxygen-ordering superstructures in underdopedYBa2Cu3O6Zimmermann1, Schneider2, Frello3 et al. 2003Phys. Rev. B825740View full textAdd to dashboardCite

“…However, no other experiments with bulk structural techniques, could confirm these results. Bertinotti et al 52 and Yakhou et al 53 have shown that the reflections of the herringbone type can be assigned to BaCu 3 O 4 grains in the crystals. Krekels et al 54,55 attribute the 2 √ 2 a × 2 √ 2 a × c structure to distortions of the CuO 5 pyramids in the CuO 2 planes, and Werder et al 56 suggest that they could result from ordering of copper and barium vacancies in the lattice.…”

BaCu3O4: High-temperature magnetic order in one-dimensionalSRischau1, Léridon2, Colson3 et al. 2012Phys. Rev. B6030View full textAdd to dashboardCite

“…The micro-Raman spectrum is displayed in Figure 3. BaCu 3 O 4 was identified for the first time as a secondary phase in YBCO samples by Bertinotti et al using X-ray diffraction (XRD) [9] and confirmed later [10]. Since BaCu 3 O 4 is metastable and only grows epitaxially on YBCO or other perovskite structures, there are only few studies (among them Raman spectroscopy [17,18]) of this material and its magnetic properties are unknown.…”

“…The magnetic structure of these Cu 3 O 4 layers results in two AF ordering temperatures and has been the focus of extensive experimental and theoretical studies (see [7,8] and Refs therein). Here we report on the magnetic properties of the alkaline earth oxocuprate BaCu 3 O 4 which is composed of Cu 3 O 4 layers [9,10] with a different structure than those of the 2234 materials, and, as will be demonstrated, very different magnetic properties. As a matter of fact, BaCu 3 O 4 exists only as a parasitic phase in YBCO samples [9], or on thin films grown on top of a suitable, epitaxial perovskite buffer layer [11].…”

Oxygen-ordering superstructures inNdBa2Cu3O6.5Frello1, Andersen2, Madsen3 et al. 2000Phys. Rev. B7020View full textAdd to dashboardCite

“…The temperature dependence and long-time recovery at room-temperature annealing demonstrate that the diffuse reflections truly originate from oxygen ordering and not from lattice distortions or some impurity phase as, e.g., observed in some Y-123 samples. 22,23 The symmetry of the superstruc- ture reflections is different from the ''herringbone'' superstructure suggested in Ref. 12, as the two possible orientations of this structure can never give both the Q 2 and Q 3 reflections.…”