Low temperature domain structure in (ND4)2TeCl6 detected by deuteron NMR spectroscopy

Deuteron NMR spectroscopy was applied to measure the tunnelling with low-temperature plateau values equal to 0.5 and 2.2 MHz frequency of ND4+ ions in ammonium hexachlorotellurate below 45 K. Two spectral components with different tunnelling frequencies were found below the order–disorder phase transition. They are attributed to ND4+ ions in ordered domains (about 75% abundance) and transition regions between them. The temperature dependence of the tunnelling frequency was measured for both regions, with low-temperature plateau values equal to 0.5 and 2.2 MHz, respectively.