R. Keitel

Cd-Impurities in the semiconductor in2Te5 studied by the PAC-method

The temperature dependence of the electric field gradient at a Cd acceptor atom in the semiconductor In2Te5 was measured with the PAC-method. The results are explained in a bond-switching model.

Lattice defects in zinc studied by the perturbed angular correlation method

Abstract After the quenching of polycrystalline zinc, a simple defect is observed between annealing temperatures 150 K ⩽ T A ⩽ 240 K. Arguments are given for a vacancy type defect being mobile in recovery stage III in Zn.

The magnetic moment of the first 2+ state in22Ne

Theg-factor of the 1,275 keV 2+ state in22Ne has been measured by means of the time-differential recoil-into-vacuum (plunger) technique. An analysis including excited heliumlike electronic configuration was performed. A fit, which includes all these electronic states, provides a value of ¦g¦=0.36±0.03.

The effect of temperature and concentration on the electric field gradient in binary indium alloys

The concentration and temperature dependence of the quadrupole hyperfine interaction of111Cd in InTl (hcp),InPb (fct),InTl (fct) andInCd (fct and fcc) alloys were studied using the perturbed angular correlation technique. The change in the observed quadrupole interaction frequency with concentration can be described by a linear dependence on the axial ratioc/a in all cases. In the alloys with identical crystal structures the strength of thec/a dependence is independent of the solute, in contrast to the strength of the concentration dependence. In all cases where no phase transition occurs, the change in the electric field gradient with temperature follows the empirical relationVzz(T)=Vzz(0) · (1−B·T3/2), where the coefficientB depends on the lattice structure, on the solute-solvent combination and on the concentration. The phase transitions ofInCd alloys at 293 K could clearly be seen as discontinuities in the temperature curves. A similar series of discontinuities observed around 116 K suggests the existence of a cubic low temperature phase.

Quadrupole Interaction in Noncubic Metals and Alloys

During the last few years the perturbed angular correlation method /1/ has proved to be a powerful experimental tool for investigating the electric field gradient (efg) in metals via the nuclear quadrupole interaction. The basic principles of the method are discussed. Recent experimental results are given for pure metals and highly diluted systems as well as for alloys. Also theoretical aspects of the temperature dependence of the efg in pure non-transition metals are discussed.