Vacancies selectively induced and specifically detected on the two sublattices of the intermetallic compound MoSi2

In the present study vacancies were selectively induced on the Si or predominantly on the Mo sublattices of MoSi 2 single crystals by low-temperature irradiation with electrons of low or high energies. These vacancies were specifically detected by employing two-detector Doppler broadening measurements of the positron-electron annihilation γ quanta in addition to positron lifetime studies. Positron lifetime studies show that two kinds of vacancies on either the Si or the Mo sublattices were induced in MoSi 2 by 0.5- or 3-MeV electron irradiation. After 0.5-MeV electron irradiation Doppler broadening spectra characteristic for Mo are detected, which shows that the vacancies with the 139 ps positron lifetime are located on the Si sublattice. After 3-MeV electron irradiation, only Si atoms were detected to surround the vacancy with the 156 ps positron lifetime, which demonstrates that in this case positrons are predominantly trapped by vacancies on the Mo sublattice. In the present experiment the selective introduction of vacancies and the detection of their location on different sublattices have proven to be a promising technique for specifically studying atomic defects in solids with a complex structure.

[1]  H. Schaefer,et al.  Identification of Vacancies on each Sublattice of SiC by Coincident Doppler Broadening of the Positron Annihilation Photons after Electron Irradiation , 2001 .

[2]  H. Schaefer,et al.  Activation Volume and Chemical Environment of Atomic Vacancies in Intermetallic Compounds , 2001 .

[3]  R. Nieminen,et al.  Calculated Positron Annihilation Parameters for Defects in SiC , 2001 .

[4]  M. Yamaguchi,et al.  Effects of alloying elements on plastic deformation of single crystals of MoSi2 , 2000 .

[5]  M. Hasegawa,et al.  Chemical analysis of precipitates in metallic alloys using coincidence Doppler broadening of positron annihilation radiation , 2000 .

[6]  Y. Kawazoe,et al.  Positron confinement in ultrafine embedded particles: Quantum-dot-like state in an Fe-Cu alloy , 2000 .

[7]  H. Schaefer,et al.  TIME-DIFFERENTIAL LENGTH CHANGE MEASUREMENTS FOR THERMAL DEFECT INVESTIGATIONS : INTERMETALLIC B2-FEAL AND B2-NIAL COMPOUNDS, A CASE STUDY , 1999 .

[8]  E. George,et al.  Thermal vacancies and the yield anomaly of FeAl , 1998 .

[9]  E. Arzt,et al.  Thermal Vacancies and High-Temperature Mechanical Properties of FeAl , 1997 .

[10]  H. Schaefer,et al.  Systematics of Thermal Defect Formation, Migration and of Self-Diffusion in Intermetallic Compounds , 1997 .

[11]  T. Nakamoto,et al.  Microstructure and mechanical properties of MoSi2 single crystals and directionally solidified MoSi2-Based alloys , 1997 .

[12]  Saarinen,et al.  Observation of compensating Ga vacancies in highly Si-doped GaAs. , 1996, Physical review. B, Condensed matter.

[13]  Saarinen,et al.  Identification of the Native Vacancy Defects in Both Sublattices of ZnSx Se1-x by Positron Annihilation. , 1996, Physical review letters.

[14]  Lynn,et al.  Increased Elemental Specificity of Positron Annihilation Spectra. , 1996, Physical review letters.

[15]  Schaefer,et al.  Characterization of radiation-induced lattice vacancies in intermetallic compounds by means of positron-lifetime studies. , 1996, Physical review. B, Condensed matter.

[16]  M. Yamaguchi,et al.  Vacancies and their clusters in MoSi2 studied by positron lifetime spectrometry , 1996 .

[17]  Saarinen,et al.  Identification of vacancy defects in compound semiconductors by core-electron annihilation: Application to InP. , 1995, Physical review. B, Condensed matter.

[18]  A. Heuer,et al.  High temperature plastic anisotropy in MoSi2 single crystals , 1995 .

[19]  A. L. Barry,et al.  Energy dependence of electron damage and displacement threshold energy in 6H silicon carbide , 1991 .

[20]  D. Gosset,et al.  Electron irradiation damage in stoichiometric and substoichiometric tantalum carbides TaC x part 1: Thershold displacement energies , 1991 .

[21]  Freeman,et al.  Phase stability and magnetism of Ni3Al. , 1990, Physical review. B, Condensed matter.

[22]  H. Fujita,et al.  Electron-irradiation-induced crystalline to amorphous transition in α-Sic single crystals , 1990 .

[23]  R. Nieminen,et al.  Positron affinities for elemental metals , 1989 .

[24]  E. Kenik,et al.  Electron microscopy of electron damage in tantalum carbide , 1988 .

[25]  H. Schaefer.  Investigation of Thermal Equilibrium Vacancies in Metals by Positron Annihilation , 1987 .

[26]  J. Sénateur,et al.  Displacement threshold energies in the A-15 compound V3Si , 1985 .

[27]  D. Lesueur,et al.  Displacement threshold energies in binary compounds: Amorphous metallic alloy Fe75B25, low dimensional conductors TaS2 and TaS3, homogeneous intermediate valence compound SmS , 1983 .

[28]  F. Rullier-Albenque,et al.  An experimental argument — in Nb3Ge — for the Labbé-Barisic-Friedel theory of A-15 superconductors , 1981 .

[29]  K. Lynn,et al.  Vacancies studied by positron annihilation with high-momentum core electrons , 1979 .

[30]  C. Muller,et al.  Band structure and X‐ray investigation of transition metal aluminides , 1979 .