Indium Flux Synthesis of RE₄Ni₂InGe₄ (RE = Dy, Ho, Er, and Tm): An Ordered Quaternary Variation on the Binary Phase Mg₅Si₆

The quaternary compounds RE4Ni2InGe4 (RE = Dy, Ho, Er, and Tm) were obtained as large single crystals in high yields from reactions run in liquid In. The title compounds crystallize in the monoclinic C2/m space group with the Mg5Si6 structure type with lattice parameters a = 15.420(2) Å, b = 4.2224(7) Å, c = 7.0191(11) Å, and β = 108.589(2)° for Dy4Ni2InGe4, a = 15.373(4) Å, b = 4.2101(9) Å, c = 6.9935(15) Å, and β = 108.600(3)° for Ho4Ni2InGe4, a = 15.334(7) Å, b = 4.1937(19) Å, c = 6.975(3) Å, and β =108.472(7)° for Er4Ni2InGe4, and a = 15.253(2) Å, b = 4.1747(6) Å, c = 6.9460(9) Å, and β = 108.535(2)° for Tm4Ni2InGe4. RE4Ni2InGe4 formed in liquid In from a melt that was rich in the rare-earth component. These compounds are polar intermetallic phases with a cationic rare-earth substructure embedded in a transition metal and main group matrix. The rare-earth atoms form a highly condensed network, leading to interatomic distances that are similar to those found in the elemental lanthanides themselves. The Dy and Ho analogues display two maxima in the susceptibility, suggesting antiferromagnetic ordering behavior and an accompanying spin reorientation. The Er analogue shows only one maximum in the susceptibility, and no magnetic ordering was observed for the Tm compound down to 2 K.四元化合物RE₄Ni₂InGe₄（其中RE指代镝（Dy）、钬（Ho）、铒（Er）与铥（Tm））通过在液态铟中进行的反应以高产率获得了大尺寸单晶。标题化合物属于单斜晶系C2/m空间群，为Mg₅Si₆型结构，其中Dy₄Ni₂InGe₄的晶格参数为a=15.420(2) Å，b=4.2224(7) Å，c=7.0191(11) Å，β=108.589(2)°；Ho₄Ni₂InGe₄的晶格参数为a=15.373(4) Å，b=4.2101(9) Å，c=6.9935(15) Å，β=108.600(3)°；Er₄Ni₂InGe₄的晶格参数为a=15.334(7) Å，b=4.1937(19) Å，c=6.975(3) Å，β=108.472(7)°；Tm₄Ni₂InGe₄的晶格参数为a=15.253(2) Å，b=4.1747(6) Å，c=6.9460(9) Å，β=108.535(2)°。RE₄Ni₂InGe₄由富稀土组分的熔体在液态铟中反应生成。此类化合物属于极性金属间相，其阳离子型稀土亚结构嵌入于过渡金属与主族元素构成的基质中。稀土原子形成高度缩合的原子网络，原子间距离与单质镧系元素中的原子间距相近。镝和钬对应的化合物的磁化率曲线呈现两个峰值，表明其存在反铁磁有序行为并伴随自旋重取向；铒对应的化合物磁化率仅出现一个峰值；而铥对应的化合物在低至2 K的温度下未观测到磁有序现象。