Rotating-frame nuclear magnetic resonance study of the distinct dynamics of hydrogen donors in ZnO

Abstract

The rotating-frame spin-lattice relaxation of two types of the hydrogen donors was well distinguished in the 1H nuclear magnetic resonance measurements in a sol-gel prepared ZnO system, providing a unique opportunity to study the distinct proton dynamics. Our study indicates interconversion of the interstitial H (Hi). The population of the mobile Hi showed decrease above ∼370 K, apparently being trapping into the oxygen vacancies resulting in the more stable oxygen-substitutional H (HO). The activation barrier for migration of Hi and the binding energy of HO were found to be 0.27 eV and 0.51 eV, respectively.

Interplay between interstitial and substitutional hydrogen donors in ZnO

“…Note that recent NMR investigations have shown that at temperatures above 370 K, interstitial hydrogen becomes trapped at the oxygen vacancy with the energy gain of 0.51 eV [58], which gives us further support for the assignment of the 273 cm −1 line to the H O donor. Figure 8 presents Raman spectra of an isochronal annealing series of a ZnO sample that was treated in a mixture of D 2 and H 2 .…”