A high-resolution natural abundance 33 S MAS NMR study of the cementitious mineral ettringite
A high-resolution natural abundance 33 S MAS NMR study of the cementitious mineral ettringite
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胶凝矿物钙矾石的高分辨率自然丰度 33 S MAS NMR 研究
DOI：
10.1039/c7cp04435f
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发表时间：
2017
影响因子：
3.3
通讯作者：
Sasaki A
中科院分区：
文献类型：
--
作者：
Sasaki A
尽管硫广泛存在于天然和人造材料中，但33 S核很少用于固态NMR光谱学，因为它的天然丰度非常低（0.76%），NMR频率低（在B 0 = 9.4 T时ν0 = 30.7 MHz）和显著的核四极矩（自旋I = 3/2，Q = −69.4 mb）。卫星跃迁魔角自旋（英语：Satellite-transition magic angle spinning，简称STMAS）是一种用于获得固体中半整数四极核（自旋I > 1/2）的高分辨率谱的NMR方法，其固有的灵敏度优于类似的多量子（MQMAS）方法，特别是对于低NMR频率的核。在这项工作中，我们证明了在B 0 = 9.4 T和20.0 T的天然丰度33 S STMAS NMR实验的可行性，使用模型硫酸盐样品（Na 2SO 4 + K2 SO 4在1：1的摩尔比）。 此外，我们对水泥形成矿物钙矾石进行了天然丰度的33 S STMAS NMR研究（Ca6Al2（SO4）3（OH）12·26H2O），B0 = 9.4 T和20.0 T，解决文献中两个先前常规33 S MAS NMR研究之间的差异，并获得一组替代的33 S NMR参数，该参数同时与两个位置的MAS和STMAS数据一致，磁场强度
Despite the widespread occurrence of sulfur in both natural and man-made materials, the 33S nucleus has only rarely been utilised in solid-state NMR spectroscopy on account of its very low natural abundance (0.76%), low NMR frequency (ν0 = 30.7 MHz at B0 = 9.4 T), and significant nuclear quadrupole moment (spin I = 3/2, Q = −69.4 mb). Satellite-transition magic angle spinning (STMAS) is an NMR method for obtaining high-resolution spectra of half-integer quadrupolar nuclei (spin I > 1/2) in solids and is notable for its intrinsic sensitivity advantage over the similar multiple-quantum (MQMAS) method, especially for nuclei with low NMR frequencies. In this work we demonstrate the feasibility of natural abundance 33S STMAS NMR experiments at B0 = 9.4 T and 20.0 T using a model sulfate sample (Na2SO4 + K2SO4 in a 1 : 1 molar ratio). Furthermore, we undertake a natural abundance 33S STMAS NMR study of the cement-forming mineral ettringite (Ca6Al2(SO4)3(OH)12·26H2O) at B0 = 9.4 T and 20.0 T, resolving a discrepancy in the literature between two previous conventional 33S MAS NMR studies and obtaining an alternative set of 33S NMR parameters that is simultaneously consistent with the MAS and STMAS data at both field strengths.