Structure and Mossbauer studies of F-O ordering in antiferromagnetic perovskite PbFeO2F
Structure and Mossbauer studies of F-O ordering in antiferromagnetic perovskite PbFeO2F
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DOI：
10.1021/cm048125g
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发表时间：
2005-03-22
影响因子：
8.6
通讯作者：
Fourquet, JL
中科院分区：
文献类型：
--
作者：
Inaguma, Y;Greneche, JM;Fourquet, JL
PbFeO_2F的合成是在高压下通过固相反应实现的。该钙钛矿在Sg Pm(3)中晶化，a=0.39991(1)nm。粉末X射线衍射数据的Rietveld精修表明，该化合物的平均结构如下：(1)Pb离子从12(110)方向的1a Wyackoff位置静态向阴离子(O，F)移动；(2)Fe离子位于单一晶位。相反，从不同温度下的穆斯堡尔谱估算的超精细数据表明，存在不同的Fe位置，并且异构体位移与位于FeO4F2八面体单元中的高自旋(HS)Fe3+离子的存在一致，其中阴离子是随机分布的。因此，这种分布有利于两个主要的Fe位置，即顺式和反式。电子衍射实验没有发现PbFeO2F中存在O/F有序化的证据。最后，场穆斯堡尔谱明确地揭示了PbFe2OF的反铁磁体行为，这与静态磁性测量是一致的。
The synthesis of PbFeO2F is achieved using a solid-state reaction under high pressure. This perovskite crystallizes in SG Pm (3) over barm (No. 221) with a = 0.39991 (1) nm. The Rietveld refinement using powder X-ray diffraction data shows that the mean structure of this compound can be characterized as follows: (1) the Pb ion statically shifts from the 1a Wyckoff position in the twelve (110) direction toward anions (O, F), and (2) the Fe ion is located in a single crystallographic site. In contrast, hyperfine data estimated from Mossbauer spectra at different temperatures suggest the existence of different Fe sites, and the isomer shift is consistent with the presence of high-spin (HS) Fe3+ ions located in FeO4F2 octahedral units, where anions are randomly distributed. Such a distribution thus favors two prevailing Fe sites, namely cis and trans. No evidence of O/F ordering in PbFeO2F was detected by electron diffraction experiments. Finally, in-field Mossbauer spectra unambiguously reveal that PbFe2OF behaves as an antiferromagnet, which is consistent with static magnetic measurements.