Delattre James L, Stacy Angelica M, Young Victor G, Long Gary J, Hermann Raphaël, Grandjean Fernande
Department of Chemistry, University of California-Berkeley, Berkeley, California 94720, USA.
Inorg Chem. 2002 Jun 3;41(11):2834-8. doi: 10.1021/ic0113247.
Crystals of Ba(2)FeO(4) and Ba(3)FeO(5), grown from a "self-sealing" KOH-Ba(OH)(2) flux, have been characterized by single-crystal X-ray diffraction, Mössbauer spectroscopy, and magnetic measurements. Ba(2)FeO(4) forms nonmerohedral twinned crystals with the monoclinic space group P2(1)/n, a = 6.034(2) A, b = 7.647(2) A, c = 10.162(3) A, beta = 92.931(6) degrees, and Z = 4. Ba(3)FeO(5) crystallizes in the orthorhombic space group Pnma, with a = 10.301(1) A, b = 8.151(1) A, c = 7.611(1) A, and Z = 4. While both compounds feature discrete FeO(4)(4-) tetrahedra, the anion found in Ba(2)FeO(4) has shorter Fe-O bonds and is significantly distorted relative to the Ba(3)FeO(5) anion. An iron valence of 4+ was confirmed by magnet susceptibility measurements and by the low-temperature isomer shifts of -0.152 and -0.142 mm/s relative to alpha-iron for Ba(2)FeO(4) and Ba(3)FeO(5), respectively.
通过“自密封”KOH-Ba(OH)₂助熔剂生长出的Ba₂FeO₄和Ba₃FeO₅晶体，已通过单晶X射线衍射、穆斯堡尔光谱和磁性测量进行了表征。Ba₂FeO₄形成具有单斜空间群P2₁/n的非merohedral孪晶，a = 6.034(2) Å，b = 7.647(2) Å，c = 10.162(3) Å，β = 92.931(6)°，Z = 4。Ba₃FeO₅结晶于正交空间群Pnma，a = 10.301(1) Å，b = 8.151(1) Å，c = 7.611(1) Å，Z = 4。虽然这两种化合物都具有离散的FeO₄⁴⁻四面体，但在Ba₂FeO₄中发现的阴离子具有较短的Fe-O键，并且相对于Ba₃FeO₅阴离子明显扭曲。通过磁化率测量以及相对于α-铁，Ba₂FeO₄和Ba₃FeO₅的低温同质异能位移分别为-0.152和-0.142 mm/s，证实了铁的化合价为4⁺。
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