Kunath-Fandrei G, Rehak P, Steuernagel S, Schneider H, Jäger C
Friedrich-Schiller Universität Jena, PATF, Germany.
Solid State Nucl Magn Reson. 1994 Sep;3(5):241-8. doi: 10.1016/0926-2040(94)90001-9.
27Al Nuclear magnetic resonance (NMR) satellite transition spectroscopy has been used for the quantitative investigation of the microstructure of polycrystalline 2/1-type mullite (approximately 76 wt.-% Al2O3 and 24 wt.-% SiO2). Using this method the chemical shifts, quadrupole interaction parameters and relative amount of Al in the various coordination polyhedra have been obtained with high accuracy. The additional suppression of second-order quadrupolar broadening of the 27Al magic-angle spinning (MAS) spinning sidebands of the inner satellite transitions allows three different AlO4 units to be detected. The three AlO4 resonances with isotropic chemical shifts at 68, 53 and 45 ppm are associated with AlO4 polyhedra in the tetrahedral double chains [AlO4(T)], the tetrahedra adjacent to the oxygen vacancies [AlO4(T*)] and the tetrahedra AlO4(T') linked by Oc* with AlO4(T*), respectively. Our NMR study of a polycrystalline sample supports the results of previous single-crystal studies of Angel et al. [Am. Mineral., 76 (1991) 332], especially the exclusion of silicon from the tetrahedral sites linked by Oc*.
27Al核磁共振（NMR）卫星跃迁光谱已用于对多晶2/1型莫来石（约76重量％的Al2O3和24重量％的SiO2）微观结构的定量研究。使用这种方法，可以高精度地获得化学位移、四极相互作用参数以及各种配位多面体中Al的相对含量。对内部卫星跃迁的27Al魔角旋转（MAS）旋转边带的二阶四极展宽的额外抑制，使得能够检测到三种不同的AlO4单元。具有68、53和45 ppm各向同性化学位移的三个AlO4共振分别与四面体双链[AlO4(T)]中的AlO4多面体、与氧空位相邻的四面体[AlO4(T*)]以及通过Oc与AlO4(T)相连的四面体AlO4(T')相关。我们对多晶样品的NMR研究支持了Angel等人先前单晶研究的结果[《美国矿物学家》，76 (1991) 332]，特别是硅被排除在由Oc*连接的四面体位点之外。
