Novel Rare-earth-containing Manganites Ba4REMn3O12 (RE = Ce and Pr) with 12R Structure
A.F. Fuentes; K. Boulahya; U. Amador. Novel Rare-earth-containing Manganites Ba4REMn3O12 (RE = Ce and Pr) with 12R Structure. Journal of Solid State Chemistry (ISSN: 0022-4596). 2004, Vol. 177, p. 714-2004.
Novel rare-earth-containing manganites, Ba4REMn3O12 (RE=Ce, Pr), with 12R structure, have been prepared by solid-state reaction. Although the phases are formed at 950 C, to obtain single-phase samples high temperatures (up to 1300 C) and long synthesis periods are needed. Their structure is built up from chains of BO6 face-sharing and corner-sharing octahedra running along the c-axis giving a quasione-dimensional oxide. Every polyhedral column consists of (Mn3O12) units of three face-sharing octahedra, both ends connected by the three terminal oxygen atoms to three different (REO6) octahedra. Mixed occupation of the three octahedral positions in the
structure, (Mn(1), Mn(2) and Re), was not found. Vacancies are not observed, neither in the cationic sublattice nor in the oxygen one. Thus, as in all the other 1-D manganites, the oxidation state of manganese ions seems to be four, as the rare-earth valence is. High-resolution electron microscopy suggests the eventual existence of ordered polytypes for different compositions, which could be stabilized by adjusting the thermodynamic conditions
Novel rare-earth-containing manganites, Ba4REMn3O12 (RE=Ce, Pr), with 12R structure, have been prepared by solid-state reaction. Although the phases are formed at 950 C, to obtain single-phase samples high temperatures (up to 1300 C) and long synthesis periods are needed. Their structure is built up from chains of BO6 face-sharing and corner-sharing octahedra running along the c-axis giving a quasione-dimensional oxide. Every polyhedral column consists of (Mn3O12) units of three face-sharing octahedra, both ends connected by the three terminal oxygen atoms to three different (REO6) octahedra. Mixed occupation of the three octahedral positions in the
structure, (Mn(1), Mn(2) and Re), was not found. Vacancies are not observed, neither in the cationic sublattice nor in the oxygen one. Thus, as in all the other 1-D manganites, the oxidation state of manganese ions seems to be four, as the rare-earth valence is. High-resolution electron microscopy suggests the eventual existence of ordered polytypes for different compositions, which could be stabilized by adjusting the thermodynamic conditions