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Submitted on 1 Jan 1974
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MÖSSBAUER INVESTIGATION OF AMORPHOUS AND POLYCRYSTALLINE TELLURIUM
N. Blum, C. Feldman
To cite this version:
N. Blum, C. Feldman. MÖSSBAUER INVESTIGATION OF AMORPHOUS AND POLY- CRYSTALLINE TELLURIUM. Journal de Physique Colloques, 1974, 35 (C6), pp.C6-401-C6-401.
�10.1051/jphyscol:1974677�. �jpa-00215834�
NON CRYSTALLINE MATERIALS.
MOSSBAUER INVESTIGATION OF AMORPHOUS AND POLYCRYSTALLINE TELLURIUM
N. A. BLUM and C. FELDMAN
The Johns Hopkins University Applied Physics Laboratory Silver Spring, Maryland 20910 U. S. A.
RBsumB. - La comparaison des spectres Mossbauer de 125Te dans des films de Te amorphes et cristallins montre que dans la phase amorphe I'interaction quadrupolaire est Iegerement plus Blevke et que la fraction de resonance est reduite a environ un tiers de sa valeur dans la phase cristalline. Ces changements sont interpretks comme indiquant une diminution de la longueur de liaison covalente entre ions tellure proches voisins dans I'6tat amorphe et de plus que des liaisons oscillantes aux extrk- mites des chaines de tellure provoquent un changement de la densite d'6tats de phonons du systeme.
Abstract. - Mossbauer spectra were obtained for 125Te enriched tellurium films
-
2 pm thick.The films were prepared in an amorphous form by careful evaporation in a vacuum onto cooled copper substrates. The amorphous films were crystallized in situ by warming to room temperature.
The spectrum of the polycrystalline film is quite similar to that obtained in powders [I] except for a rather pronounced asymmetry in the strengths of the quadrupole doublet components. The asym- metry is entirely due to a preferred crystalline orientation such that the [0001] axis is perpendicular to the substrate [2, 31. In the amorphous film, the asymmetry between the intensities of the quadru- pole doublet lines remains, the recoil-free-fraction is diminished by a factor of about three, and there is a slight increase in the quadrupole splitting.
Despite the apparent orientation effect in the amorphous phase, the sample can be shown to be truly amorphous in the usual sense of exhibiting no long range order. The increase in the quadru- pole splitting when the sample is amorphous can be correlated with a slight decrease in the lengths of the covalent bonds along the spiral chain of Te atoms [4]. The Mossbauer results are compared with the results of experiments by others on amorphous Te using Raman scattering, electron diffraction, and photoemission spectroscopy techniques.
This work has been reported elsewhere [ 5 ] .
References
[I] VIOLET, C. E. and BOOTH, R., Phys. Rev. 144 (1966) 225.
[2] KUZMIN, R. N., OPALENKO, A. A., SHPINEL', V. S. and AVENARIUS, I. A., SOY. Phys. JETP 29 (1969) 94 (trans- lated from the Russian).
[3] OPALENKO, A. A. et al., Sov. Phys. JETP 35 (1972) 547 (translated from the Russian).
[4] BOOLCHAND, P., HENNEBERGER, T. and OBERSCHMIDT, J., Phys. Rev. Lett. 30 (1973) 1292.
151 BLUM, N. A. and FELDMAN, C., Solid State Commun. 15 (1974) 965-968.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1974677
