Mn Self-Doping of Orthorhombic RMnO3 Perovskites: (R0.667Mn0.333)MnO3 with R = Er-Lu

Lei Zhang; Dominic Gerlach; Andreas Dönni; Toyohiro Chikyow; Yoshio Katsuya; Masahiko Tanaka; Shigenori Ueda; Kazunari Yamaura; Alexei A Belik

doi:10.1021/acs.inorgchem.7b03188

Mn Self-Doping of Orthorhombic RMnO₃ Perovskites: (R_0.667Mn_0.333)MnO₃ with R = Er-Lu

Inorg Chem. 2018 Mar 5;57(5):2773-2781. doi: 10.1021/acs.inorgchem.7b03188. Epub 2018 Feb 12.

Authors

Lei Zhang¹, Dominic Gerlach, Andreas Dönni, Toyohiro Chikyow, Yoshio Katsuya², Masahiko Tanaka², Shigenori Ueda^{2

3}, Kazunari Yamaura¹, Alexei A Belik

Affiliations

¹ Graduate School of Chemical Sciences and Engineering , Hokkaido University , North 10 West 8, Kita-ku , Sapporo , Hokkaido 060-0810 , Japan.
² Synchrotron X-ray Station at SPring-8 , National Institute for Materials Science , Kouto 1-1-1 , Sayo-cho , Hyogo 679-5148 , Japan.
³ Research Center for Advanced Measurement and Characterization , National Institute for Materials Science , Sengen 1-2-1 , Tsukuba , Ibaraki 305-0047 , Japan.

PMID: 29431431
DOI: 10.1021/acs.inorgchem.7b03188

Abstract

Orthorhombic rare-earth trivalent manganites RMnO₃ (R = Er-Lu) were self-doped with Mn to form (R_0.667Mn_0.333)MnO₃ compositions, which were synthesized by a high-pressure, high-temperature method at 6 GPa and about 1670 K from R₂O₃ and Mn₂O₃. The average oxidation state of Mn is 3+ in (R_0.667Mn_0.333)MnO₃. However, Mn enters the A site in the oxidation state of 2+, creating the average oxidation state of 3.333+ at the B site. The presence of Mn²⁺ was confirmed by hard X-ray photoelectron spectroscopy measurements. Crystal structures were studied by synchrotron powder X-ray diffraction. (R_0.667Mn_0.333)MnO₃ crystallizes in space group Pnma with a = 5.50348(2) Å, b = 7.37564(1) Å, and c = 5.18686(1) Å for (Lu_0.667Mn_0.333)MnO₃ at 293 K, and they are isostructural with the parent RMnO₃ manganites. Compared with RMnO₃, (R_0.667Mn_0.333)MnO₃ exhibits enhanced Néel temperatures of about T_N1 = 106-110 K and ferrimagnetic or canted antiferromagnetic properties. Compounds with R = Er and Tm show additional magnetic transitions at about T_N2 = 9-16 K. (Tm_0.667Mn_0.333)MnO₃ exhibits a magnetization reversal or negative magnetization effect with a compensation temperature of about 16 K.