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High‐Pressure Synthesis and Magnetic Behavior of A‐Site Columnar‐Ordered Double Perovskites, LnMn(Ga 0.5 Ti 0.5 ) 2 O 6 (Ln = Sm, Gd)
Author(s) -
Shimura Gen,
Niwa Ken,
Shirako Yuichi,
Hasegawa Masashi
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201601392
Subject(s) - antiferromagnetism , crystallography , chemistry , rietveld refinement , ferromagnetism , magnetization , ionic radius , curie temperature , diffraction , condensed matter physics , synchrotron , crystal structure , lattice constant , x ray crystallography , space group , powder diffraction , ionic bonding , ion , magnetic field , physics , nuclear physics , organic chemistry , quantum mechanics , optics
A‐site columnar‐ordered double perovskites, LnMn(Ga 0.5 Ti 0.5 ) 2 O 6 (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 P 4 2 / nmc space group with lattice parameters a, c ≈ 2 a p ( a p : 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 Ln 3+ Mn 2+ (Ga 3+ 0.5 Ti 4+ 0.5 ) 2 O 2– 6 . SmMn(Ga 0.5 Ti 0.5 ) 2 O 6 shows canted‐antiferromagnetic behavior, whereas GdMn(Ga 0.5 Ti 0.5 ) 2 O 6 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 Ga 3+ ( d 10 ) for Ti 4+ ( d 0 ) and by decreasing the ferromagnetic interaction between columnar‐ordered Ln 3+ and Mn 2+ .