Behavior of Mn~(3+) ions in four-layered hexagonal (Sr_(1 - x - y)La_xBa_y)MnO_3

摘要

Stoichiometric four-layered hexagonal (4H) (Sr_(1 - x - y)Ba_xLa_y)MnO_3 was synthesized using a standard ceramic technique. Rietveld analysis at room temperature indicated that the Mn-O(1) distance increased and the Mn-O(2) distance decreased with the increase in x. The samples were n-type semiconductors and exhibited hopping conductivity in a small-polaron model below 533 K. The Mn~(3+) ion acted as a donor and the electron transfer became active through the Mn~(3+)-O-Mn~(4+) path. The samples were antiferromagnetic and the Neel temperature (T_N) was constant regardless of y when x was fixed to 0.3, whereas T_N shifted to a high temperature when y was fixed to 0.02. The face-sharing Mn~(3+)-O(2)-Mn~(4+) interaction strengthened as the Mn-O(2) distance decreased, and T_N shifted to a high temperature as a result.