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Title: High-pressure synthesis and characterization of BiCu{sub 3}(Mn{sub 4−x}Fe{sub x})O{sub 12} (x=0, 1.0, 2.0) complex perovskites

We have studied the series of nominal composition BiCu{sub 3}(Mn{sub 4−x}Fe{sub x})O{sub 12} (x=0, 1.0, 2.0) where Mn is replaced by Fe cations in the ferrimagnetic perovskite BiCu{sub 3}Mn{sub 4}O{sub 12}. These compounds have been prepared from citrate precursors under moderate pressure conditions (3.5 GPa) and 1000 °C in the presence of KClO{sub 4} as oxidizing agent. All the samples have been studied by x-ray and neutron powder diffraction (NPD) at room temperature and 4 K. The crystal structure has been defined in a cubic Im3{sup ¯} (No. 204) space group with a 2a{sub 0}×2a{sub 0}×2a{sub 0} unit-cell. The doubling of the unit-cell occurs due to the ordering of Bi{sup 3+} and Cu{sup 2+} cations over A sites of the AA′{sub 3}B{sub 4}O{sub 12} structure. The A-site accommodates 12-fold coordinated Bi{sup 3+} ions and, at the A′-site, Jahn–Teller Cu{sup 2+} ions form pseudo-square planar units aligned perpendicular to each other. Mn{sup 4+}/Fe{sup 3+} cations randomly occupy the centre of slightly distorted octahedra. These materials have also been characterized by magnetic and magnetotransport measurements. We found that all the samples are ferrimagnetic and show a progressive decrease of T{sub C} as the Fe content increases, since Fe ions disturb the ferromagneticmore » interactions within the B magnetic sublattice. In fact, the Curie temperature diminishes from T{sub C}=360 K (x=0) to T{sub C}=219 K (x=2). The magnetic structures, studied by low-temperature NPD data, correspond to an antiferromagnetic arrangement of spins at 8c and 6b sites; the ordered moments are in excellent agreement with those obtained from the saturation magnetization at 4 K. A significant magnetoresistant effect is determined for the x=1.0 oxide, with low-field values as high as 5% at 300 K and 1 T. Highlights: • BiCu{sub 3}(Mn{sub 4−x}Fe{sub x})O{sub 12} perovskites have been prepared under high pressure conditions. • They have been characterized by NPD, magnetic and magnetotransport measures. • The introduction of Fe leads to a transition from metallic to semiconducting. • Curie temperature decreases as the Fe content increases.« less
Authors:
 [1] ; ;  [1] ;  [2] ;  [3]
  1. Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco E-28049, Madrid 28049 (Spain)
  2. Departamento de Química Física I, Facultad de Ciencias Químicas, Universidad Complutense, 28040 Madrid (Spain)
  3. Institut Laue Langevin, BP 156X, Grenoble F-38042 (France)
Publication Date:
OSTI Identifier:
22274023
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 204; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANTIFERROMAGNETISM; BISMUTH IONS; CATIONS; COPPER IONS; CUBIC LATTICES; CURIE POINT; INTERACTIONS; IRON IONS; MAGNETIZATION; MAGNETORESISTANCE; MANGANESE IONS; NEUTRON DIFFRACTION; OXIDES; PEROVSKITE; POTASSIUM PERCHLORATES; PRESSURE RANGE MEGA PA 10-100; SPACE GROUPS; SYNTHESIS; X RADIATION