Neue Pnictide im CaAl2Si2-Typ und dessen Existenzgebiet/New Pnictides with the CaAl2Si2 Type Structure and the Stability Range of this Type
Neue Pnictide im CaAl2Si2-Typ und dessen Existenzgebiet/New Pnictides with the CaAl2Si2 Type Structure and the Stability Range of this Type
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DOI：
10.1515/znb-2002-1112
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发表时间：
2002-11
期刊：
影响因子：
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通讯作者：
F. Wartenberg;C. Kranenberg;R. Pocha;D. Johrendt;A. Mewis;R. Hoffmann;B. Mosel;R. Poettgen
中科院分区：
文献类型：
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作者：
F. Wartenberg;C. Kranenberg;R. Pocha;D. Johrendt;A. Mewis;R. Hoffmann;B. Mosel;R. Poettgen
在600 ~ 1000℃的温度下，合成了5个新化合物，并用粉末和单晶x射线方法对其进行了研究。EuMg2P2 (a = 4.280（1), c = 7.164(3) Å）、EuMg2As2 (a = 4.393（1), c = 7.321(1) Å）、EuMg2Sb2 (a = 4.695（1), c = 7.724(2) Å）、YbMg2Sb2 (a = 4.650（1), c = 7.540(2) Å）和SrLiAlSb2 (a = 4.584（3), c = 7.697(9) Å）以CaAl2Si2型结构（P3 m1; Z = 1）结晶。EuMg2Sb2的磁化率表现出居里-魏斯行为，实验磁矩为7.48(2)μB/Eu原子，Weiss常数θ = 3.2(1) K。EuMg2Sb2在8.2(3)K时呈有序反铁磁，4.5 K时磁化率呈线性增加，5.5 T时磁矩为5.9(1)μB/Eu达到饱和，表明随着场强的增加，自旋排列几乎平行。151Eu Mössbauer在78 K时的光谱显示异构体位移为-11.69(5)mm/s，与二价铕相容。在4.2 K下，121Sb光谱显示了8(2)T的转移超细场，同分异构体位移为-7.9(3)mm/s。从EuMg2Sb2的能带结构可以得出结论，由于电子的原因，CaAl2Si2型结构的三价稀土金属不应该存在类似的化合物。
Five new compounds were synthesized by heating mixtures of the elements at 600 - 1000 °C and investigated by powder and single crystal X-ray methods. EuMg2P2 (a = 4.280(1), c = 7.164(3) Å), EuMg2As2 (a = 4.393(1), c = 7.321(1) Å),EuMg2Sb2 (a = 4.695(1), c = 7.724(2) Å), YbMg2Sb2 (a = 4.650(1), c = 7.540(2) Å), and SrLiAlSb2 (a = 4.584(3), c = 7.697(9) Å) crystallize with the CaAl2Si2 type structure (P3̄m1; Z = 1). The magnetic susceptibility of EuMg2Sb2 shows Curie-Weiss behavior with an experimental magnetic moment of 7.48(2) μB/Eu atom and a Weiss constant θ = 3.2(1) K. EuMg2Sb2 is ordered antiferromagnetically at 8.2(3) K. Magnetisation measurements at 4.5 K show a linear increase and a saturation for a magnetic moment of 5.9(1) μB/Eu at 5.5 T, indicating an almost parallel spin alignment with increasing field strength. 151Eu Mössbauer spectra at 78 K show an isomer shift of -11.69(5) mm/s, compatible with divalent europium. At 4.2 K we observe full hyperfine field splitting with 23 T. The 121Sb spectrum at 4.2 K shows a transferred hyperfine field of 8(2) T at an isomer shift of -7.9(3) mm/s. From the band structure of EuMg2Sb2 we draw the conclusion, that analogous compounds of trivalent rare-earth metals with CaAl2Si2 type structure should not exist due to electronic reasons.