High‐Pressure Synthesis and Magnetic Behavior of A‐Site Columnar‐Ordered Double Perovskites, LnMn(Ga0.5Ti0.5)2O6 (Ln = Sm, Gd)

• Published in: European journal of inorganic chemistry 2017-01, Vol.2017 (4), p.835-839
• Main Authors: Shimura, Gen, Niwa, Ken, Shirako, Yuichi, Hasegawa, Masashi
• Format: Article
• Language: English
• Subjects: Diffraction; High‐pressure chemistry; Lanthanides; Magnetic properties; Perovskite phases; Rietveld analysis; X-rays
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201601392

A‐site columnar‐ordered double perovskites, LnMn(Ga0.5Ti0.5)2O6 (Ln = Sm, Gd), were successfully synthesized under high pressure and high temperature (6 GPa, 1375 K). From the synchrotron powder X‐ray diffraction patterns, all of the diffraction peaks can be indexed by the P42/nmc space group with lattice parameters a, c ≈ 2ap (ap: primitive cubic perovskite lattice) and no ordering of the B‐site cations. Rietveld analysis of the synchrotron powder X‐ray diffraction patterns and Curie–Weiss fitting of their magnetizations reveal that the ionic formulae of these perovskites are Ln3+Mn2+(Ga3+0.5Ti4+0.5)2O2–6. SmMn(Ga0.5Ti0.5)2O6 shows canted‐antiferromagnetic behavior, whereas GdMn(Ga0.5Ti0.5)2O6 exhibits two different magnetic states at low temperature depending on the applied magnetic field and shows an unusual magnetization curve. These magnetic behaviors originate by decreasing the antiferromagnetic interaction by substituting Ga3+(d10) for Ti4+(d0) and by decreasing the ferromagnetic interaction between columnar‐ordered Ln3+ and Mn2+. A‐site columnar‐ordered double perovskites, LnMn(Ga0.5Ti0.5)2O6 (Ln = Sm, Gd), are synthesized under high pressure and high temperature (6 GPa, 1375 K). SmMn(Ga0.5Ti0.5)2O6 shows canted‐antiferromagnetic behavior, whereas GdMn(Ga0.5Ti0.5)2O6 exhibits two different magnetic states at low temperature depending on the applied magnetic field and shows an unusual magnetization curve.