TY - JOUR
T1 - Crystallographic and magnetic structures of Y0.8Sr 2.2Mn2GaO8-δ
T2 - A new vacancy-ordered perovskite structure
AU - Gillie, L. J.
AU - Palmer, H. M.
AU - Wright, A. J.
AU - Hadermann, J.
AU - Van Tendeloo, G.
AU - Greaves, C.
PY - 2004/1
Y1 - 2004/1
N2 - The anion-deficient perovskite Y0.8Sr2.2Mn 2GaO8-δ (where δ∼0.1) has been synthesised and the crystal and magnetic structures determined by Rietveld analysis of neutron powder diffraction (NPD) data. The material has body-centred tetragonal symmetry (I4/mmm, a = 7.6373(3) Å and c = 15.6636(10) Å) and consists of alternating layers of octahedral and tetrahedral polyhedra, the layers being perpendicular to [001]. The octahedral layers are preferentially occupied by manganese and the tetrahedral layers are a mixture of manganese and gallium. The precise cation distribution depends critically on preparative conditions. An unusual structural feature of these materials is the arrangement of oxygen vacancies in the tetrahedral layers: in the basic structure, isolated squares of corner-linked tetrahedra are formed instead of the chains that are observed in brownmillerite phases. Additional oxide ions in this layer probably allow the Mn ions to achieve distorted square pyramidal coordination. Low temperature NPD and magnetisation data indicate antiferromagnetic ordering below 100 K.
AB - The anion-deficient perovskite Y0.8Sr2.2Mn 2GaO8-δ (where δ∼0.1) has been synthesised and the crystal and magnetic structures determined by Rietveld analysis of neutron powder diffraction (NPD) data. The material has body-centred tetragonal symmetry (I4/mmm, a = 7.6373(3) Å and c = 15.6636(10) Å) and consists of alternating layers of octahedral and tetrahedral polyhedra, the layers being perpendicular to [001]. The octahedral layers are preferentially occupied by manganese and the tetrahedral layers are a mixture of manganese and gallium. The precise cation distribution depends critically on preparative conditions. An unusual structural feature of these materials is the arrangement of oxygen vacancies in the tetrahedral layers: in the basic structure, isolated squares of corner-linked tetrahedra are formed instead of the chains that are observed in brownmillerite phases. Additional oxide ions in this layer probably allow the Mn ions to achieve distorted square pyramidal coordination. Low temperature NPD and magnetisation data indicate antiferromagnetic ordering below 100 K.
KW - D. Magnetic structure
UR - http://www.scopus.com/inward/record.url?scp=0346903368&partnerID=8YFLogxK
UR - https://www.journals.elsevier.com/journal-of-physics-and-chemistry-of-solids
U2 - 10.1016/j.jpcs.2003.08.012
DO - 10.1016/j.jpcs.2003.08.012
M3 - Article
AN - SCOPUS:0346903368
VL - 65
SP - 87
EP - 93
JO - Journal of Physics and Chemistry of Solids
JF - Journal of Physics and Chemistry of Solids
SN - 0022-3697
IS - 1
ER -