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MÖSSBAUER STUDY OF PROTON RADIATION EFFECTS IN PERMALLOY
M. Kopcewicz, A. Kotlicki, M. Lipska
To cite this version:
M. Kopcewicz, A. Kotlicki, M. Lipska. MÖSSBAUER STUDY OF PROTON RADIATION EF- FECTS IN PERMALLOY. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-419-C1-420.
�10.1051/jphyscol:19801162�. �jpa-00219649�
JOURNAL DE PHYSIQUE Colloque C1, supplkment au no 1 , Tome41, janvier 1980, page C1-419
M~~SSBAUER SNDY OF PROTON RADIATION EFFECTS IN P E R M A W
M. Kopcewicz, A. Kotlicki and M. Lipska
I n s t i t u t e of ExperirnentaZ Physics, Warsaw University, Hoia 6 9 , 00-681 WarsW, Poland.
I n the recent years we studied prot- on radiation e f f e c t s i n various d i e l e c t r i c iron compounds by the Mllssbauer technique.
We observed such radiation e f f e c t s as ra- diation damage due t o proton irradiation, chemcal changes i n the irradiated material location of iron ions in the i n t e r s t i t i a l positions in the l a t t i c e , oxydation of Fez+ t o ~ e ~ + , Formation of the superpara- magnetic phase of the magnetic material due t o radiative decomposition was obser- ved and veryfied by Mbssbauer measurements
Sn a wide temperature range [1-4].
I n the present paper some r e s u l t s of a Mbssbauer studyof the e f f e c t of 1.8 MeV proton irradiation on permalloy a r e repor- ted, Suplementary X-ray studies of the ir- radiated samples were performed t o deter- mine the material formed during irmdia- tion.
Permalloy f o i l s of the composition
integrator, After imgdiation each sample was measured a s stationary absorber in a
constant acceleration Nokia Electronics 80, Pl8ssbauer spectrometer using a 5 7 ~ o i n palladium source of 10 mCi activity. The M6ssbauer measurements were carried out se- veral days a f t e r irradiation so only the stable changes due t o Irradiation were ob- servad. The measurements were performed in the temperature range 78-30013: using the Oxford Instruments Co. continuous flow cryostat
.
The parameters of the M6ssbauer spec- tra such as the l i n e positions, i n t e n s i t i e s linewidths and the nonresonant background l e v e l were calculated by the l e a s t square method, the Lorenzian shapes being f i t t e d t o the experimental data obtained,
The Mbssbauer spectrum of n o n i m d i a - ted permallay f o i l consists of six linea of magnetic hyparfine sp'littlng /hfs/ (Fig.1~) 7496Ni-2-e and 50%t?i-509@e, rolled t o a
thiclnress of 30
pm
and annealed i n vacuum f o r several hours a t 1200K were irradiated I n the Warsaw Van de Oraaff accelerator.Protons of energy 1.8 MeV and doses of 40" t o 5 x 1 0 ~ ~ were used. Tbe i r r a d i a t i v e
arrangement consisted of the proton beam VELOCITY collimator and water owled sample holder. Fig.1
The irradiated area was about 10 nun2* The Irradiation w i t h protons of energy 1.3 MeV proton dose was measured with a current and dose up to 5x10'~ does not a f f e c t sig-
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801162
c1-420 JOURNAL DE
nif icantly the spectrum shape ( ~ i g. IB,IC).
However, the r a t i o s of the intensity of the first t o second and sixth to f i f t h l i n e of the hfs spectrum increasein the case of Per-
mellw
749@i-24%Fe from 0.80 t o 1 -05 f o r fncreasing proton beam current. The obser- ved increase of this r a t i o (Fig,2) suggests that irradiation makes the magnetic f i e l ddirection distribution in the irradiated sample more random than it is in a nonir- radiated one. A similar but less d i s t i n c t
1 7 -
behaviour was ob-served f o r pennal- lay 5096Ni-5-e. In spectra of the f o i l s irradiated with doses of more .than 9x10~9 protons,
I I -
0 :
C
(L In-
> .
t .
In
W .
C
I"-
"
z 2
d
I,
;,_I
an additional quad- F i g 2 rupole s p l i t t i n g- -
doublet /QS/ appears beside the s i x lines of the magnetic hfs w i t h an isomer s h i f t of 0.94 mm/s with respect t o metallic iron and quadrupole s p l i t t i n g of 0.66 ~mn/s
f F i g . l ~ ) . Mf5ssbauer measurements performed
i n the temperature range 78-300K (~ig.3)
.m
.
show t h a t the QSm"
doublet disappears
P a ,
a t about 207K. This suggests that the QS doublet corres- ponds t o the forma- tion of a material
VELOCITY ""l revealing a magne-
Fig03 t i c transition a t about 207K and the hfs lines corresponding t o this meterial are not resolved frola the permalloy lines.
PHYSIQUE
I n the X-ray spectrum of the sample f o r which the QS doublet was observed the distinct; l i n e s corresponding t o the FeO oxide were found. The parameters of the doublet are irr good agreement w i t h those observed f o r FeO [5,63.
The s t a b i l i t y of the material formed whose content in the sample did not change even a f t e r several months f r o m irradiation, suggests that it was formed in the bulk of the irradiated penualloy and not on its surface.
The oxygen necessery f o r FeO f orma- tion was probably contained in the sample i n the intercrystalline spaces.
The authors are indepted t o D r I.
Sosnarska f o r her kind interest i n this study. Thanks are also due t o Dr T-Panek of the Silesian University for making available the Fe-Ni samples, and t o Mr.
S .Fi jakkowski f o r technical assistance.
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3,
(1 978) ,1409.5. G
.
Shirane,
DOE .Cox, S .L.Ruby, Phy s .Rev.B,
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2,
(7 969) ,I 785.