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Rare-earth solid-state NMR spectroscopy of intermetallic compounds: The case of the 175Lu isotope.
Solid State Nuclear Magnetic Resonance ( IF 1.8 ) Pub Date : 2019-05-08 , DOI: 10.1016/j.ssnmr.2019.05.003
Christopher Benndorf 1 , Marcos de Oliveira Junior 2 , Henrik Bradtmüller 3 , Frank Stegemann 4 , Rainer Pöttgen 4 , Hellmut Eckert 5
Affiliation  

The feasibility of high-resolution 175Lu solid-state NMR spectroscopy in intermetallic compounds crystallizing with cubic crystal structures is explored by magic-angle spinning NMR at different magnetic flux densities. The large quadrupole moment of this isotope (3.49 × 10−28 m2) restricts observation of the NMR signal to nearly perfectly ordered crystalline samples. Signals are successfully detected and analyzed in the binary pnictides LuPn (NaCl-type structure; Pn = P, As, Sb) and the intermetallic compounds LuPtSb and LuAuSn, both crystallizing with the MgAgAs-type structure. Sources of line broadening are discussed based on field-dependent static and MAS-NMR spectra, providing guidance with respect to measurement conditions resulting in reliable results. The results highlight the importance of ionic/covalent bonding effects for the detectability of the signal, which reduce the probability of real structure effects commonly observed in intermetallic compounds. No 175Lu NMR signals can be observed in various cubic Heusler compounds. This is attributed to mixed site occupancies and other structural defects producing electric field gradients whose interaction with the 175Lu quadrupole moments broadens the signal beyond detection.



中文翻译:

金属间化合物的稀土固态NMR光谱:以175Lu同位素为例。

通过魔角旋转NMR在不同的磁通密度下探索了高分辨率的175 Lu固态NMR光谱在立方晶结构结晶的金属间化合物中的可行性。该同位素的大四极矩(3.49×10 -28 m 2)将NMR信号的观察限制在几乎完美有序的晶体样品中。在二元肽Lu Pn(NaCl型结构;Pn)中成功检测和分析了信号 = P,As,Sb)和金属间化合物LuPtSb和LuAuSn,均以MgAgAs型结构结晶。基于场相关的静态光谱和MAS-NMR光谱讨论了谱线展宽的来源,为获得可靠结果的测量条件提供了指导。结果突出了离子/共价键合效应对于信号可检测性的重要性,这降低了通常在金属间化合物中观察到的实际结构效应的可能性。无175个NMR信号可以以各种立方霍伊斯勒化合物被观察到。这归因于混合的位置占用和其他结构缺陷,产生电场梯度,这些电场梯度与175 Lu四极矩的相互作用将信号拓宽到无法检测的程度。

更新日期:2019-05-08
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