The recent progress in NMR of glasses is demonstrated using both traditional and improved two‐dimensional (2D) NMR techniques. A novel approach for measuring connectivities Qn units in amorphous and polycrystalline solids is explained. Several examples of phosphate samples are presented to show e.g. how chain end groups can be distinguished from pyrophosphate units. Additionally, novel results of 27Al NMR investigations in mullites and Na2O‐SiO2‐Al2O3 glasses were obtained using a careful lineshape analysis. In mullites three different AlO4 units can be found including an estimation of the relative Al occupancy of the various groups. In ternary Na2O‐Al2O3‐SiO2 glasses we could prove the presence of two AlO4 sites with Al being surrounded by four Q3 units or possibly one terminal oxygen instead of a Q3 unit (60 ppm) and by four Q4 groups (53 ppm). Finally, two different Na sites have been detected for the first time using 23Na MQ NMR in a glass 22.7 Na2O 0.7 B2O 69.8 SiO2.
A home-built spectrometer for solid-state nuclear magnetic resonance (NMR) spectroscopy with stochastic excitation is described. An overview of the instrument is given and selected components are explained in more detail. These are the control unit and the module for the pulse generation. Furthermore, a static probe with crossed coils for the transmitter and receiver circuits and the data processing part of the spectrometer software are described. The pulse unit can generate pulse trains with up to 219 pulses. Also, pulse-width-modulated sequences with automatic pulse centering can be produced. Using the crossed coil, probe decoupling between transmitter and receiver of more than 80 dB is possible. Several examples of NMR measurements are shown, which include selective excitation in solids and the acquisition of static H2 solid state NMR spectra with a spectral width of up to 185 kHz.
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