Electric field gradient at the 111Cd(←111In) site in Ga-doped ZnO

The time-differential perturbed angular correlation (TDPAC) method was applied to a study of the local environment at the 111Cd(←111In) probe nucleus introduced in 0.5 at. % Ga-doped ZnO. The TDPAC spectrum obtained at room temperature suggests that the doped Ga ions reside at the substitutional Zn site and they are locally associated in immediate proximity to the probe, reflecting strong attractive force between the probe and the dopants. The relative width of the magnitude of the electric field gradient produced at the probe nucleus shows that the doped Ga ion(s) adjacent to the probe is/are diversely distributed compared with doped In ion(s).

Nuclear Quadrupolar Relaxation m Liquid Alloys and Nearest Neighbour Dynamics

A theory of the quadrupolar relaxation rate,RQ , for ideal liquid binary metallic mixtures ispresented. The theory predicts cancellation after a few tenths of a picosecond of the two andthree particle correlation terms in the fluctuation of the electric field gradient (EFG) for puremetals, and prevailing of the three particle term for binary mixtures. This is due to the highsymmetry in the arrangement of the atoms around a probe nucleus. The prevailing of the threeparticle term in binary systems leads to a longer correlation time (a few picoseconds) of thefluctuating EFG and explains the experimentally observed higher values of RQ and theirquadratic concentration dependence. The validity of the theory has been confirmed by experimentaldata. Deviations for some real systems are discussed.