CHEMICAL INTERACTION OF TIN ATOMS, SURROUNDED BY CADMIUM AND INDIUM ATOMS IN TETRAHEDRAL STRUCTURES

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CHEMICAL INTERACTION OF TIN ATOMS, SURROUNDED BY CADMIUM AND INDIUM

ATOMS IN TETRAHEDRAL STRUCTURES

C. Vaičiuliné, K. Makariùnas, A. Dragùnas, B. Morozova

To cite this version:

C. Vaičiuliné, K. Makariùnas, A. Dragùnas, B. Morozova. CHEMICAL INTERACTION OF TIN ATOMS, SURROUNDED BY CADMIUM AND INDIUM ATOMS IN TETRAHE- DRAL STRUCTURES. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-303-C1-304.

�10.1051/jphyscol:19801109�. �jpa-00219590�

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JOURNAL DE PHYSIQUE Colloque C1, supplkment au n

"

1 , Tome 41, janvier 1980, page C1-303

CHEMICAL INTERACTION OF TIN ATOMS, SURROUNDED BY CADMIUM AND INDIUM ATOMS IN TETRAHEDM STRUCNRES

C. ~ a i c i u l i e n i ? , K. Makariiinas, A. Dragiinas and B. Morozova

I n s t i t u t e of Physics, Academy of Sciences of the Lithuanian SSR, 232000 V<Znius, USSR,

Tin atorns in tetrahedral seniconduc- tors usually occupy sites ill cation sublattice. In some co~!~plex compounds, hom- ever, tin atoms occupy sites in anion sublattice and are tetrahedrally surrouq- ded by fom metal atoms. Chemical interaction of tin ator.1~ in such cases is not clear up to nom.

Fl6ssbauer exp eriinent s were carried out to investigate this problem. Compounds Cd21n6Sn32e5, Cd21i12SnTe3 and CagIn2SnTe7 in ~rhich tin atoms are surrounded by cadmium and indim- atoms (fig.

i),

were pre- pared. These compounds can be regarded as solid solutions of CdTe and of tile hypo- thetical compound iiz2SnTe, i. e. ( 2CdTe)x- (In2SnFe)l-x ( ~ ~ 0 . 2 5 ; 0.5 and 0.75, res- pectively). The conpounds were synthesiz- ed by melting of the initial elements in evacuated quartz ampules. Tin was used natural and enriched with the isotope 'I9sn in such a proportion that the ab- sorbers of equal thickileas tvould have equal thickness of llSsn (1 .w/cm 2 ). X- ray analysis has shown ';bat crystal lattice of these compounds is of sphalerite type, the lattice constants of all three compounds are almost equel (difference s m l l e r than 0.3%) and are very close to the crystal lattice constant of C d ~ e .

Fig. 1

-

Environment of tin atoms in three compounds: a) Cd21n6Sn3Te5, b) Cd21n2SnTe3, c) Cd61n2Snle7.

rossbauer spectra ??ere measured using constant ncceleration spectrometer.

'19sn source in palladium was used. All the measurements were performed at room temperature.

All the measured spectra consisted of one broad line (fi:;. 2). Characteristic feattzre was very lovr intensity of the spectral lines (about one order of mag- nitude lower as compared to tetrahedral coxpounds with tin atoms in cation sublattice), what indicates small T:Ibssbauer effect probability and, consequently, weak chemical bond.

I . .

. . . . . . . . -

^>

-4 -2

D

2 4 V,mm/s

Pig. 2

-

Iii6ssbauer spectrum of Cd21n6SngTe5.

Isomer shifts (IS), the measured values and also volues recalculated relative to standard BaSn03 source, are presented in the table. To obtain the values of the IS relative to BaSn03, the IS of Sn02 relative to our source was measured (-1.73'0.02 mm/s) and the published value of SnO2 IS relative to BaSnOj (0.08 mm/s ) was used. The published values of the IS ford-Sn

(the IS of 119~n in compounds of tetrahedral semiconductors with tin atoms in

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801109

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C1-304 JOURNAL DE PHYSIQUE

cation sublattice are very close to this value [2] )

,

for metallic -Sn and for tin

P

in indium 111 are also presented in the table. The IS values of the compounds investigated, evidently, are in the re- gion more characteristic of bivalent tin and of tin atoms in metals, in spite of tetrahedral coordination (characteristic of quadrivalent tin), and of the typical to tetrahedral seaicondv.ctors crystal lattice parameters. This result can be regarded as indicating considerable over- lap of the regions of the isomer shifts of bivalent and quadrivalent tin.

Table

Isomer shifts relative to the sources

'lgmsn in Pd (measured) and ~ a ~ ~ ~ ~ n 0 ~ (recalculated).

Chenicel bond of tin atom under in- vestigation appears to be the superposi- tion of the covalent boric, characteristfc of quad-rivalent tin nnd responsible for the tetrahedral coordfnation,and of the other types of bonds (probably there is strong metallization of bonds). Some in- crease of the IS with the increasing number of the surrounding cadmium atoms can possibly be related with the redis- tribution of electronic charge in electronic brid-yes which bind tin atons with the neighbowing atoms (with stronger shift of the charge of the bindini: elec- trons to tin atoms).

13ibliography

1 P.A. minn, in "Bbssbauer Isomer Shifts", ed. G.X. Shenoy, Worth Xol- land, Amsterdam, 1978, p. 597.

Compound IS (Sn in Pd) IS (BaSn03) 2 A.K. Draganas, K.V. ::kkariiinas, in mm/s mm/ s "Proceedings 5th International. Con- Cd21n6Sn3Te5 0.93f-0.02 2.74*0.04 ference on ISdssbauer Spectroscopy Cd21n2SnTe3 1.0020.02 2.8120.04 (Bratislava, 1973)", Praha 1975,

p. 517.

Cd61npSnTe7 l.03k0 .02 2.8420.04