The Study on the Effect of Nonstoichiometry on Thermal Equilibrium Defects in Intermetallic Compounds by Positron Annihilation
| Project/Area Number |
02452230
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Physical properties of metals
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| Research Institution | University of Tsukuba |
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Principal Investigator |
TANIGAWA Shoichiro University of Tsukuba Institute of Materials Science Associate Professor, 物質工学系, 助教授 (90011080)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥5,900,000 (Direct Cost: ¥5,900,000)
Fiscal Year 1991: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1990: ¥4,400,000 (Direct Cost: ¥4,400,000)
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| Keywords | intermetallic compound / positron annihilation / nonstoichiometry |
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| Research Abstract |
The effect of nonstoichiometry on thermal equilibrium defects in intermetallic compounds was studied by positron annihilation. The measurements of positron annihilation were carried out by means of the positrdn lifetime spectroscopy, the Doppler broadening spectroscopy, the two dimensional angular correlation of annihilation radiations and the slow positron analysis. The following results were obtained :
(1) Defects introduced by nonstoichiometry in TiAl and TiAl_3 :
The positron annihilation characteristics were measured as a function of the alloy compositions of the above alloys in their one phase region. As a result, it was found that the concentration of vacancy-type defects introduced by the nonstoichiometric composition is quite lower than the detection limit of the positron annihilation technique. This result clearly shows that the extra alloy elements form the antisite defects. From the thermal equilibrium experiment performed by the use of ^<48>V positon source, which was for the first time developed in the present research program, a greater num ber of divacancies were introduced in these intermetallic compounds as compared with In pure metals.
(2) Determination of three dimensional momentum space density of electrons in beta'-AgZn :
By the measurements of 2D-ACAR spectra with different crystal orientations followed the image reconstruction technique, the three dimensional momentum space density of electrons in beta'-AgZn was determined. The experimentally determined density coincides well with the theoretically expected one. In this case, the extra alloy elements also occupy the antisite lalttice points.
In addition, the determination of thd densities in NiAl, Ni_3Al and NbSe_2 was carried out successfully.
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Report
(3 results)
Research Products
(28 results)
