MÖSSBAUER STUDY OF RESISTIBILITY TO OXIDATION OF THIN FILMS Sn1-xPbxTe AND Sn1-xPbxSe

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MÖSSBAUER STUDY OF RESISTIBILITY TO OXIDATION OF THIN FILMS Sn1-xPbxTe AND

Sn1-xPbxSe

A. Amulevičius, D. Baltrùnas, I. Brodin, D. Freik, K. Makariùnas, J.

Solonichnyj

To cite this version:

A. Amulevičius, D. Baltrùnas, I. Brodin, D. Freik, K. Makariùnas, et al.. MÖSSBAUER STUDY OF RESISTIBILITY TO OXIDATION OF THIN FILMS Sn1-xPbxTe AND Sn1-xPbxSe. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-327-C1-328. �10.1051/jphyscol:19801121�. �jpa-00219604�

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JOURNAL DE PHYSIQUE CoNoque C1, supplkment au n O 1 , Tome 41, janvier 1980, page C1-327

aSBAUER STUDY OF RESISTIBILITY TO OXIDATION OF THIN FILMS Snl-XPb,Te AND Snl,,We

"

A. Amulevicius, D. Baltriinas, I. Brodin, D. F r e i k , K. Makariiinas and J. Solonichnyj

i n s t i t u t e o f P h g s i c s , Academy o f S c i e n c e s of t h e L i t h u a n i a n SSR, 232000 V i l n i u s , USSR.

ivano-Frankovsk Pedagogical I n s t i t u t e , 284000 Ivano-Frankovsk, USSR.

A wide use of thin films of compounds A ~ B " and their aqlogues in technique requires thorough investigation of their physical and chemical properties. One of these is the resistibility to oxidation of the thin films.

The initial film samples on mica back- ings were sedimented out of the gas dyna- mica1 flow of vapour in double quasi-

closed volume [I], The thickness of the films was 8-20 mkm. Oxidation of the samples was performed in air in the temperature range 423-873 K from 6 to 180 minu- tes. The measurements were taken at room temperature using ~al'~~n0 source. The 3 thickness of the absorbers was 10-15

%/em 2 of natural tin.

'The measurements of the l\Iossbauer spectra showed that in the samples Snl-xPbxTe under oxidation two forms of tin appear

-

the initial and Sn02. When oxidizing the films Snl,Pb,Se, 3 forms of tin appear: the initial, Sn02 and Sn506Se4 (fig. 1). For identification of

Fig. 1

-

~~ossbauer spectrum of the oxidized system of the thin films Snl-xPbxSe decomposed into the components 1

-

^Sn02;

2

-

^Sn506Se4;³

-

^SnSe,

the latter form the results of vror:: 123 and the results of the resolution of the measured spectra into coniponents were used (the program for the least square fit of the measured TIossbauer spectra vms used). The quantity of every chemi-

cal form of tin in the sample investigated was determined by comparison of normalized areas of the corresponding Xossbauer lines.

all investigations were performed in four stages. In the first stage to de- termine the threshold, of oxidation the temperature was changed at the fixed heating time (3 hours). The results are presented in table 1.

Table 1

Percentage of the oxidized forms of tin depending on the oxidation temperat~u'e (thickness of the films 15 mlan, duration of the oxidation 3 hours).

--- - -

Initial Oxidized Oxidation sample form of temperatme K

tin 420 570 670 770 PbO.lSnO. 9!!! e Sn02 0 0 0 100

-- p ~-~ - ~ -- -

In the second stage the dependence of the amou~t of Sn02 on the time of heating was investigated at the fixed temperature. The results are presented in fig, 2.

In the third stage the heating tempex8,- ture was fixed and the dependence of t'ne oxidation rate on the -thickness of the film was investigated. The results axe presented in fig. 3. In the fourth stage at the fixed heating teixperature the time

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801121

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Cl-328 ^JOURNAL^DE^PHYSIQUE

The results obtained show that the

sf

^SnTe ^{4 l ~ k} decrease of the amount of tin in the

A !

composition of the films as well as the prolongation of the duration of the heat- izg accelerate the oxidation process. The products of the oxidation appear at the besinning in the defect places and form solid oxide layer when the temperature and the duration of heating increase.

Table 2

Percentage of Sn02 (for Snl-,PbxTe) and Eli.:,.. 2

-

Percentsge of 3nD2 d-ependins on

Sn02-Sn506Se4 (for Snl-xPb,Se) depending t3.e time of heat treatnent. Fila thick-

on the oxidation tine (thickness of the ness nlzd te~cereture e r e indicated in

films 15 mkm, oxidation temperature the figure.

720 K).

ha

SnTe

T=

773K

7

h=ayk

I I I I I

Initial films Duration of the o:ci?.ation,

=in

7 20 50 100

-- -

SnT e 3 7 39 7 5

SnO.

pO,

lTe 8 19 58 84 yPbO. 3Te 10 ^{2 5} 60 100

Pig. 3

-

Percentace of 8rr0, depending on

L

t h e film thicknesn.

.oT the heat treatment ??as chafi@ed end the dependence of the thermal stability on phase co~~posi.tion (on x values) YJGS stu-

died. The results rre presented in table 2.

I":etallograp'nical investigations were carried out too. Tiley showed. that in the process of the ilea% treatmelt at the bezimling small oval form par$icles of the oxide phases display on the ver,Tes of microcrystalo. Vith the temperature increase the crystallites of the oxide phase grow and ,pedually cover the crys- tal verges, forming later the surface structure.

- - -

Bibliography

1 D.1, saltranas, A.K. Dragtinas, J.V.

Solonichnyj

,

D.F6. Freik, 1.V. Uel9ni- chuk. Liet. Fiz. Rinkinys,

18

(1978) 631.

2 L.R. Vasi19ev, 1I.V. Nakeeva, Yu.V.

ICry19nikov, L.N. Seregina. J. Beorg.

mater. (1977) 1752.