Correlation between the crystal structure and the Curie temperature in RCu sub(3)(Mn sub(3)Fe)O sub(12) (R = rare-earth) complex perovskites

• Published in: Dalton transactions : an international journal of inorganic chemistry 2012-08, Vol.41 (35), p.10670-10679
• Main Authors: Kayser, Paula, Martinez-Lope, Maria Jesus, Retuerto, Maria, Sanchez-Benitez, Javier, Fernandez-Diaz, Maria Teresa, Alonso, Jose Antonio
• Format: Article
• Language: English
• Subjects: Citrates; Correlation; Curie temperature; Diffraction; Iron; Oxides; Perovskite structure; Rare earth metals
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt30647f

New members of the family of complex-perovskite oxides with the formula RCu sub(3)(Mn sub(3)Fe)O sub(12) (R = Ce, Pr, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) have been synthesized and characterized. Polycrystalline samples have been prepared from citrate precursors treated under moderate pressure conditions (2-3.5 GPa) and 1000 degree C in the presence of KClO sub(4) as an oxidizing agent. All the samples have been studied by neutron powder diffraction (NPD) at 300 K and 2 K. These oxides crystallize in the cubic space group Im3&cmb.macr; (no. 204). Mn super(4+)/Mn super(3+) and Fe super(3+) occupy at random the octahedral B positions of the perovskite structure. These materials have also been characterized by magnetic and magnetotransport measurements. The observed enhancement of T sub(C) along the RCu sub(3)(Mn sub(3)Fe)O sub(12) series is understood as an effect of the chemical pressure on the (Mn,Fe)-O bonds as R super(3+) size decreases. The semiconducting behaviour observed in all of the samples is related with the introduction of Fe at B position. Despite the drastic change of the transport properties, significant negative magnetoresistance values are observed in the Fe-containing compounds both at 10 K and 300 K.