MÖSSBAUER EFFECT STUDY OF THE ANNEALING OF 57[MATH]AL, IMPLANTED AT 4.2K

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MÖSSBAUER EFFECT STUDY OF THE

ANNEALING OF 57[MATH]AL, IMPLANTED AT 4.2K

E. Verbiest, H. Pattyn, J. Odeurs

To cite this version:

E. Verbiest, H. Pattyn, J. Odeurs. MÖSSBAUER EFFECT STUDY OF THE ANNEALING OF

57[MATH]AL, IMPLANTED AT 4.2K. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-431-C1-

432. �10.1051/jphyscol:19801168�. �jpa-00219655�

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JOURNAL DE PHYSIQUE Colloque C1, suppl6ment au n O 1, Tome 41, janvier 1980, page (21-431

MOSSBAUER EFFECT STUDY OF THE ANNEALING OF 57&I

IMPLANiED

AT 4.2 K

E. Verbiest, H. Pattyn and J. Odeurs

I n s t i t u u t voor Kern- en StraZingsfysika, Leuven University, B-3030 Leuven, BeZgiwn.

1. EXPERIMENTAL PROCEDURE

5 7 ~ o has been implanted .into a polycristalline 14 2 Al-foil (6N) at 4.2 K to a total dose of 10 at/cm with an energy of 85 keV. A description of the fa- cility will be given elsewhere /I/. Thereafter Mgssbauer effect measurements have been performed on the 14.4 keV line of 5 7 ~ e at 4.2 K as implanted and at 4.2 K and 40 K after isochronal (30') annealing steps at the,temperatures : 75, 125, 150, 175, 200, 225, 250, 275, 300, 325, 375 K. A K4Fe(CN)6.

3H20 absorber, giving a theoretical linewidth of 0.30 m / s , was moved at R.T.

2. EXPERIMENTAL RESULTS

Fig. 1 shows some of the spectra recorded with the source at 4.2 K. All spectra are fitted with a single line and two doublets. The parameters giving the best fit are displayed in table 1. All line- widths are larger than 0.30 mm/s which may be due to oscillations of the source or to a distribution of unresolved hyperfine interactions.

TABLE 1.

The exact values of the relative areas, the isomer shifts and the splittings are not determined very well due to the poor resolution of the lines, while the relative changes of the relative area's are ob- served very clearly.

To investigate the behaviour of the recoilless frac- tion of line 2 we calculated : F 2 = area2 (source at 40 K)/area2 (source at 4.2 K). The F -value as

2 measured after stage I1 was 0.83 (7).

3. DISCUSSION OF THE RESULTS

The site identification is straightforward.

Line 1 and line 2 were also found in the work of Vogl and coworkers /2/ /3/ and in agreement with

them we attribute line 1 to the substitutional site (s-site) and line 2 to an interstitial site

,

^the

<loo>

mixed dumbbell. Line 3, is in accordance

with /4/ identified as a site where Co is associated with one vacancy (v-site)

.

The increasing intensity of line 3 upon annealing through stage 111 (200 K) confirms this assignment. In fact, stage I11 annealing is due to the migration of an intrin- sic point defect. This cannot be an interstitial, while this would increase the population of the i- site, which is decreasing. So it has to be the vacancy that migrates, thus increasing the v-site.

These assignments promote the Co-atom to the role of 'universal trapper' in Al. Rinneberg et al. /5/

have shown that In plays the same role in Al..

Fig 2. Bhows the site populations as a function of the annealing temperature. The relative areas of the lines, as given in table 1, can be used immedia- tely as relative populations, as it has been shown /6/ 141 that the recoilless fractions of the three sites are the same at 4.2 K.

line 3 -0.33 mm/s

0.0 mm/s

15 15 3 1

?.O

One of the striking features in fig. 2 is the high i-site population after implantation. This will be explained in terms of replacement-collision- probability calculations 171.

A second remarkable aspect is the absence of drastic changes in the populations after stage I

(<55 K) annealing. A probable reason is a much snaller radius for interstitial trapping at the substitutional Co than at the Co in the mixed dumbbell line 2

-0.16 mm/s 0.18 mm/s

38 29 13 SO IS

Splitting Rel. area i n % a t T =

ann 4.2

-

^{100 K}

1 0 0 - 1 9 0 K 190

-

300 K

3 350 K

configuration. This then-agrees with the high F- value for the i-site, which, as calculated from /6/, indicates that about 100 % of the Co-atoms in the i-site are associated with more than 1 interstitial A1

.

As already mentioned, the increase of the v-site and the decrease of the i-site at 190 K (stage 111) indicate that vacancies become mobile in this stage, an observation that favours the 'one-interstitial' model

181.

The fact that the s-site population is not affected is most easily explained as a balance between growth and decrease.

As seen on fig. 2, the i-site and the v-site dis- line 1

-0.63 mm/s

-

47 56 56 00

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801168

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C1-432 JOURNAL DE PHYSIQUE

I -

-1.0

-

0.5 0.0 0.5

1

1.0 VELOCITY lrnrn/sec)

Figure 1 : 57$0g spectra at different annealing temperatures

s-site b i-site

sociate both at about 350 K, leaving all Co-atoms in the s-site. Why this should happen for both sites at the same temperature is an open question.

4. CONCLUSION

We have demonstrated that ion implantation of radioactive atoms, combined with Mijssbauer Effect measurements, is a useful technique in studying annealing characteristics of metals.

Co was shown to trap vacancies as well as interstitial~ in Al, which makes it a 'universal trapper' in Al.

We confirmed the 'one-interstitial' recovery model for Al.

REFERENCES

111 Pattyn, H., Odeurs, J., Verbiest, E., to be published.

/2/ Mansel, W., Vogl, G., Koch, W., Phys. Rev. Lett.

31 (1973) 359.

131 Mansel, G., Vogl, G., J. Phys. F:Metal Phys.

7

(1977) 253.

/ 4 1 Ichinose, H., Sassa, K., Ishida, Y., Kato, M., Philos. Mag.

2

(1977) 1367.

/5/ Rinneberg, H., Semmler, W., Antesberger, G., Phys. Lett. 66A (1978) 57.

161 Mansel, W., Meyer, H., Vogl, G., Radd. Eff.

25,

(1978) 69.

171 Odeurs, J., Pattyn, H., Verbiest E., Reintsema, S.R., Coussement, R., Brice, D.K., to be published.

I 8 1 Schilling, W., Burger, G., Isebeck, K., Wenzl, H., in 'Vacancies and Interstitials in Metals', North Holl., 1970.

Figure 2 : 5 7 ~ & site populations as a function of the annealing temperature