17 O NMR Spectroscopy of α‐TeO 2 and Na 2 TeO 3

The synthesis of 17 O‐enriched α‐tellurite (α‐TeO 2 ) is described. TeO 2 is obtained stochiometrically by the reaction of tellurium isopropoxide with 17 O‐enriched H 2 O. The reaction is mild and simple and opens the field of tellurite‐based ceramics to 17 O nuclear magnetic resonance spectroscopy. We also report the first 17 O nuclear magnetic resonance spectra of α‐TeO 2 and Na 2 TeO 3 . Their isotropic chemical shifts, δ iso , are 180 ppm and 158 ppm, respectively, and their quadrupolar coupling parameters are C Q =7.48 MHz and η=0.43 for α‐TeO 2 , and C Q =6.63 MHz and η=0.33. By using extended Hückel tight binding calculations, we interpret the chemical shifts of tetravalent inorganic oxide network formers (SiO 2 , GeO 2 , and TeO 2 ) in terms of the local paramagnetic shielding effect. We also show that this is the predominant effect in determining the chemical shifts of non‐bridging oxide sites in this type of network.