Vacancies were selectively induced on the Si or predominantly on the Mo sub-lattices of MoSi2 single crystals by low-temperature irradiation with electrons of low or high energies. These vacancies were specifically detected by employing 2-detector Doppler broadening measurements of the positron-electron annihilation γ quanta in addition to positron lifetime studies. Positron lifetime studies showed that 2 kinds of vacancies on either the Si or the Mo sub-lattices were induced in MoSi2 by 0.5 or 3MeV electron irradiation. After 0.5MeV irradiation, Doppler broadening spectra characteristic for Mo were detected, which showed that the vacancies with the 139ps positron lifetime were located on the Si sub-lattice. After 3MeV electron irradiation, only Si atoms were detected to surround the vacancy with the 156ps positron lifetime, which demonstrates that in this case positrons were predominantly trapped by vacancies on the Mo sub-lattice.

Vacancies Selectively Induced and Specifically Detected on the Two Sublattices of the Intermetallic Compound MoSi2. X.Y.Zhang, W.Sprengel, K.Blaurock, A.A.Rempel, K.J.Reichle, K.Reimann, H.Inui, H.E.Schaefer: Physical Review B, 2002, 66[14], 144105 (5pp)