Pr 62 Fe 21 M 16 C 32 Versus Pr 21 Fe 8 M 7 ′ C 12 (M = Si, P; M′ = Si, Ge, Sn): Competing Intermetallic Carbides Grown from a Pr/Ni Flux
Pr 62 Fe 21 M 16 C 32 Versus Pr 21 Fe 8 M 7 ′ C 12 (M = Si, P; M′ = Si, Ge, Sn): Competing Intermetallic Carbides Grown from a Pr/Ni Flux
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Pr 62 Fe 21 M 16 C 32 与 Pr 21 Fe 8 M 7 – C 12（M = Si、P；M – = Si、Ge、Sn）：由 Pr/Ni 助熔剂生长的竞争性金属间碳化物
DOI：
10.1021/acs.inorgchem.8b02741
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发表时间：
2018
影响因子：
4.6
通讯作者：
Latturner, Susan E.
中科院分区：
文献类型：
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作者：
Engstrand, Tate O.;Latturner, Susan E.
硅、碳和铁在低熔点的镨和镍的熔剂混合物中发生反应，产生了两种相互竞争的金属间化合物。Pr_（62）Fe_（21）Si_（16）C_（32）具有一种新的结构类型，空间群为P_4/mmm（a= 15.584（2）nm，c= 11.330（1）nm，Z= 1），其特征是具有三角平面结构的FeC_（33）单元，这些单元共享角，形成圆柱形通道的框架，包围着以硅为中心的Praseo_3簇的网络。反应物比例和加热曲线的轻微变化产生Pr 21 Fe 8 Si 7 C12，该化合物具有先前报道的立方La 21 Fe 8 Sn 7 C12结构类型。在两种结构类型中发现了相同的Pr/Si团簇和FeC 3亚基基模体。除了反应物比例和加热曲线外，尺寸效应在决定形成何种结构中也起作用。用较小的磷原子取代硅只产生四元结构;用较大的元素（M = Ge，Sn）取代只产生立方结构的Pr 21 Fe 8 M7 C12。对Pr_（62）Fe_（21）Si_（16）C_（32）单晶的磁化率测量表明，Pr磁矩在17 K以下是反铁磁有序的，铁原子上没有磁矩。Pr 21 Fe 8 Si 7 C12的行为更为复杂，揭示了Pr和Fe原子的磁性贡献以及可能的自旋阻挫。
Reactions of silicon, carbon, and iron in a low-melting flux mixture of praseodymium and nickel produced two competing intermetallic compounds. Pr62Fe21Si16C32has a new structure type in tetragonal space groupP4/mmm(a= 15.584(2) Å,c= 11.330(1) Å,Z= 1) that features trigonal planar FeC3units that share corners to form a framework of cylindrical channels encompassing a network of silicon-centered praseodymium clusters. Slight variation of reactant ratio and heating profile produced Pr21Fe8Si7C12instead; this compound has the previously reported cubic La21Fe8Sn7C12structure type. Identical Pr/Si clusters and FeC3subunit motifs are found in both structure types. In addition to reactant ratio and heating profile, size effects play a role in determining which structure forms. Replacing silicon with smaller phosphorus atoms produces only the tetragonal structure; replacement with larger elements (M = Ge, Sn) yields only cubic Pr21Fe8M7C12. Magnetic susceptibility measurements on single crystals of Pr62Fe21Si16C32indicate antiferromagnetic ordering of the Pr moments below 17 K and no magnetic moment on iron atoms. The behavior of Pr21Fe8Si7C12is more complex, revealing magnetic contributions from both Pr and Fe atoms and possible spin frustration.