TY - JOUR
T1 - Impact of lanthanoid substitution on the structural and physical properties of an infinite-layer iron oxide
AU - Yamamoto, Takafumi
AU - Ohkubo, Hiroshi
AU - Tassel, Cédric
AU - Hayashi, Naoaki
AU - Kawasaki, Shota
AU - Okada, Taku
AU - Yagi, Takehiko
AU - Hester, James
AU - Avdeev, Maxim
AU - Kobayashi, Yoji
AU - Kageyama, Hiroshi
N1 - Generated from Scopus record by KAUST IRTS on 2022-09-13
PY - 2016/11/21
Y1 - 2016/11/21
N2 - The effect of lanthanoid (Ln = Nd, Sm, Ho) substitution on the structural and physical properties of the infinite-layer iron oxide SrFeO2 was investigated by X-ray diffraction (XRD) at ambient and high pressure, neutron diffraction, and 57Fe Mössbauer spectroscopy. Ln for Sr substituted samples up to ∼30% were synthesized by topochemical reduction using CaH2. While the introduction of the smaller Ln3+ ion reduces the a axis as expected, we found an unusual expansion of the c axis as well as the volume. Rietveld refinements along with pair distribution function analysis revealed the incorporation of oxygen atoms between FeO2 layers with a charge-compensated composition of (Sr1-xLnx)FeO2+x/2, which accounts for the failed electron doping to the FeO2 layer. The incorporated partial apical oxygen or the pyramidal coordination induces incoherent buckling of the FeO2 sheet, leading to a significant reduction of the Néel temperature. High-pressure XRD experiments for (Sr0.75Ho0.25)FeO2.125 suggest a possible stabilization of an intermediate spin state in comparison with SrFeO2, revealing a certain contribution of the in-plane Fe-O distance to the pressure-induced transition.
AB - The effect of lanthanoid (Ln = Nd, Sm, Ho) substitution on the structural and physical properties of the infinite-layer iron oxide SrFeO2 was investigated by X-ray diffraction (XRD) at ambient and high pressure, neutron diffraction, and 57Fe Mössbauer spectroscopy. Ln for Sr substituted samples up to ∼30% were synthesized by topochemical reduction using CaH2. While the introduction of the smaller Ln3+ ion reduces the a axis as expected, we found an unusual expansion of the c axis as well as the volume. Rietveld refinements along with pair distribution function analysis revealed the incorporation of oxygen atoms between FeO2 layers with a charge-compensated composition of (Sr1-xLnx)FeO2+x/2, which accounts for the failed electron doping to the FeO2 layer. The incorporated partial apical oxygen or the pyramidal coordination induces incoherent buckling of the FeO2 sheet, leading to a significant reduction of the Néel temperature. High-pressure XRD experiments for (Sr0.75Ho0.25)FeO2.125 suggest a possible stabilization of an intermediate spin state in comparison with SrFeO2, revealing a certain contribution of the in-plane Fe-O distance to the pressure-induced transition.
UR - https://pubs.acs.org/doi/10.1021/acs.inorgchem.6b02513
UR - http://www.scopus.com/inward/record.url?scp=84997831959&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.6b02513
DO - 10.1021/acs.inorgchem.6b02513
M3 - Article
VL - 55
SP - 12093
EP - 12099
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 1520-510X
IS - 22
ER -