| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 1998: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1997: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
It is known from phase diagrams that the solubility of rare-earth elements (RE) in Al matrix is very small (less than 0.05 at%), so that their metallic compounds tend to be easy to form. From these facts, we chose Al-rare-earth alloy system (Al-RE) in this study and investigated the effect of their metallic compounds on a resistivity in this binary alloy system. Furthermore, we added transition metals as a third element to Al-RE binary alloy systems to perform a preliminary investigation of the above same effects. All samples were made by using a DC magnetron sputtering apparatus. The contents of rare-earth elements in binary Al-RE alloy systems (RE=Sc, Tb, Ho, Er, Tm, Yb) were varied from 1 to 7 at%. It was revealed from the experimental results that though the resistivities of as-made samples are quite high, 20- 40 muOMEGAcm, they largely decreased on annealing above 250ﾟC, at the beginning of the segregation of mainly Ad_3RE metallic compounds in Al matrix. On further annealing abov
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e 350ﾟC, we obtained very low resistivity of less than 5 muOMEGA cm (depending on their content of added RE elements), near to values of pure Al thin films (3-4 muOMEGA cm). It was concluded from TEM observations and X-ray diffraction analysis that the low resistivity resulted from the segregation of metallic compounds, together with the removal of added elements from the Al matrix. However, in spite of a large segregation of metallic compounds in Al matrix, their resistivities showed a quite low value (i.e. high conductivity), so that those of their metallic compounds themselves are thought to be very small values. In the addition of a third elements to a binary alloy film, the transition elements, such as Zr or Ta which had a repulsive interaction with RE, retarded the segregation of metallic compound and showed a relatively high resistivity even after annealing above 350ﾟC.On the contrary, the addition of Cu or Co, both of which have an attractive interaction with RE enhanced the segregation of metallic compounds, resulted in a very low resistivity. To get further insight into both the conductivity of Al-RE metallic compounds and the influence of chemical interaction between constituent atoms in Ad-RE alloy systems, the calcultion of the electron density of state of Al_3RE metallic compound is now under way. Less
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