Enhancement of surface resistivity due to anisotropic Guinier-Preston zone scattering

Abstract

The residual electrical resistivity of dilute aluminium-silver foils with thicknesses of 30-1300 mu m has been measured. The silver concentration is 0.01-0.1 at.%, and three heat treatments are used, referred to here as furnace cooling, air quenching and quenching followed by aging. The resistivities of foils show various features consistent with the presence of Guinier-Preston (GP) zones. A strong enhancement of surface resistivity rho s (=foil resistivity-bulk resistivity) is found in these foils: rho s increases with solute concentration and becomes about 4-5 times as large as that in the solid solution and in Fuchs-Sondheimer theory. The enhanced rho s decreases to about a half upon aging for six days at 350 K after quenching from 871 K. These results strongly suggest that anisotropy in GP zone scattering enhances rho s.

Anisotropy in surface resistivity due to electron-phonon scattering in aluminium

“…The values of f i l b of 0.55-0.59 fS2 mz at 1.5 K are smaller than the previous values of 1.09 fC2 mz (at 1.5 K and RRR= 27000) and 0.68 fS2 m2 (at 4.2 K and RRR= 14000) in AI polycrystalline foils (Nakamichi andKino 1980, 1988), and nearer to the theoretical one of 0.50 f a m2. The observation of the s m d pblb agrees with that on single crystals by others; Sat0 and Yonemitsu (1976) have obtained about 0.50-0.53 fQ mz for the (101) surface and current directions of [OlO] or [loll on A1 at 4.2 K. The large pblb in polycrystals is consistent with the theoretical prediction of Bate er a1 of the enhancement of pblb in polycrystals as described in the preceding section.…”

“…For single-crystal data, ps is obtained as the subtraction of pb from the measured p , using pb in table 2. The foil data on the AI-Ag polycrystal and pure AI polycrystal with RRR= 27 000 are from our previous work (Nakamichi andKino 1980, 1988). The theoretical ps is We see that ps in the polycrystal of pure AI is about twice as large as the others.…”

Strong segregation by a migrating boundary and the decrease in electrical resistivity

“…Similarly, pgb for GB40 was deduced from the p of the 6 part between PL4 and PL5 and from those of contiguous grains, where L4-5 = 1.49 nun. More experimental details have been described elsewhere (Nakamichi andKino 1986, Nakamichi 1990).…”

“…Thus, we can take pgb as equal to the amount of segregated solute multiplied by the specific solute resistivity. Using the specific resistivity of Ag in AI which is equal to 10.0 n51 m (at.%)-' (Nakamichi 1989). the ppb-value of 1.4 x C2 mz for GB39 corresponds to a length of 14 nm (SO layers) of Ag.…”

“…Firstly, the estimation of segregation is based on the assumption of mechanism (1). Secondly, the constitution of the segregation on various types of boundary in polycrystalline specimens may vary during grain growth, and this might cause the resistivity minima, because boundary resistivities depend on the boundary type and structure (Nakamichi andKino 1986, Nakamichi 1990). Thirdly, the large amount of segregation observed might be due to the dragging of solute atoms by vacancies annihilated at boundaries during cooling (referred to as vacancy drag).…”