SITE PREFERENCE OF THE 57Co IMPURITIES IN THE Fe3 (Si, Al) ALLOYS

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SITE PREFERENCE OF THE 57Co IMPURITIES IN THE Fe3 (Si, Al) ALLOYS

O. Schneeweiss, T. Zemčík, T. Žák

To cite this version:

O. Schneeweiss, T. Zemčík, T. Žák. SITE PREFERENCE OF THE 57Co IMPURITIES IN THE Fe3 (Si, Al) ALLOYS. Journal de Physique Colloques, 1980, 41 (C1), pp.C1-375-C1-376.

�10.1051/jphyscol:19801142�. �jpa-00219627�

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JOURNAL DE PHYSIQUE Colloque C1, suppldment au n O 1 , Tome 41, janvier 1980, page Cl-375

SITE PREFERENCE OF M E 5 7 IMPURITIES I N THE Fe3 ~ ~ (~i, ~ 1 ) ALLOYS

0. Schneeweiss, T. ~ e m E f k and T. Shk

Institute of PhysicaZ MetazZurgy, 616 6 2 Brno, CzechosZovakia

I n t h e p a s t , t h e s i t e ; r e f e r e n c e of c o b a l t aioE;S i n both t h e Fe S i

E]

2nd Fe3Ai [2] a l l o y s a a s s t u d i e d . The 3 a i m of t h i s work i s t o i n v e s t i g a t e t h e i n f l u e n c e o f g r a d u a l s u . b s t i t u t i o n of A1 a t o m by S i i n :he 303 type ordered a l l o y s Fe3(Si, A!., ! on t h e Co s i t e p r e f e r e a c e by t h e

57?,XiJ6ssbauer emission spectroscopy.

Zrom f o u r specimens n (x = 0.0, 0.4, C,?, 1 . 0 ) , s o u r c e s were p r e p a r e d by e l e c t - r o d s p o s i t i o n o f 5 7 ~ o from t h e c a r r i e d r e e c l i l o r i d e s o l u t i o n . D i f f u s i o n anneal (in ii, atmosphere, 1400 K/30 h r s ) was f o l l o - wed by a slow c o o l i n g between 1009 K as6

500 K t h e c o o l i n g r a t e being 5 Kh. A C C O P

d i n g t o o u r e x p e r i e n c e [3]

,

t h i s seems t o be s u f f i c i e c t f o r t h e formetion o f t k e high degree of t h e W 3 o r d e r i n t h e whole range o f compositions,

Emission UGssbauer s p e c t r a were ta- ken w i t h t h e 5 7 ~ e - e n r i c h e d potassium f e r - rocyanide absorber. The s p e c t r a were f i t - t e d by t h r e e t o f i v e independent Z e e ~ a n s i x - l i n e c o ~ p o n e n t s . A s a r e s u l t , b a r d i a g r a n s o f t h e i r r e l a t i v e i n t e n s i t i e s vs.

h y p e r f i n e s p l i t t i n g s a r e d e p i c t e d i n F i g o 1.

To den0 t e i n d i v i d u a l s u b - l a t t i c e p o i n t s i n t h e DO3 s t r u c t u r e , t h e same ccm- v e n t i o n i s used a s i n [2, 43. The A , C pi- t e s have 4 n.n. Fe atoms, t h e B, D s i t e s 8 n.n. Fe a t o n s . It i s supposed t h a t b o t h t h e A 1 and S i atoms p r e f e r t h e D s i t e s . Frorr. t h e r e s u l t s , summarized i n Fig. 1, f o l l o w i n g c o n c l u s i o n s on t h e 5 7 ~ o d i s t r i - b u t i o n between t h e A , C and B , D sub

-

l a t t i c e s were drawn:

1. c o b a l t obviously p r e f e r s t h e B - s i t e i n t h e DO3 s t r u c t u r e , having 8 n e a r e s t i r o n neighbours;

2. t h i s p r e f e r e n c e becoaes more pronoun- ced a s t h e A l t o S i s u b s t i t u t i o n t a k e s p l a c e ( i . e . w i t h i n c r e a s i n g x i .

60

--

^x^;^{0 7}

Fig. i Hyperfine f i e l d d i s t r i b u t i o n i n 57~o-doped Fe3

I n Fig. 1, t h e r e s u l t s on t h e pure Fe,Si a r e n o t i n c l u d e d , a s i t i s suspec-

_1 51

t e d t h a t t h e . 'Co d i f f u s i o n i n t o t h e sam- p l e voiuee was i n s u f f i c i e n t , The s p e c t r m o f t h i s s m p l e i m p l i c a t e s t h a t a s u r f a c e l a y e r c o n s i s t i n g almost s o l e l y o f t h e CO and Fe atoms was b u i l t . Fron t h e h i g h va- l u e s o f t h e magnetic h y p e r f i n e f i e l d (up t o 419 kOe), h i g h Co c o c c e n t r a t i o n i n t h i s l a y e r can be c ~ n c i u d e d

151.

^Slowing-

down o f t h e d i f f u s i o n of 5 7 ~ 0 l c t o t h e w e l l ordered Fe3Si i s i n agreement w i t h

t h e r e s u l t s p u b l i s h e d elsewhere [ 6 ] . Zven a small s u b s t i t u t i o n of S i by A1 s y p r e s - s e s t h e c r i t i c a l o r d e r i n g temperature t o such a n e x t e n t t h a t t h e d i f f u s i o n p r o c e s s t a k e s p l a c e i n a l e s s ordered a l l o y [7].

B e s i d e s t h e ferromagnetic c o ~ p o n e n t s o f s p e c t r a corresponding t o t h e Co a t o n s i n b o t h t h e A , C and B s i t e s of t h e DO,

d

s t r u c t u r e , a l s o a parzmagnetic component

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19801142

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c1-376 JOURNAL DE PHYSIQUE

was f o w d . O r i g i n a l l y we t h o u g h t t h a t t h e d e c r e a s e o f i t s i n t e n s i t y w i t h i n - c r e a s i n g s u b s t i t u t i o n o f A l by S i might b e dne t o t h e c o n c e n t r a t i o n dependence o f t h e d i f f u s i o n r a t e . N e v e r t h e l e s s , t h i s h a s n o t been confirmed by a supplementary R e f e r e n c e s

[l] BLA!iU'rl/, C., S o l i d S t a t e C O ~ U ~ .

18

(1976) 729.

[2] SU'JALSKI

,

^J,

,

SCHN$E'NIESS, 0.

,

ZS$?!~K, T., TUCHOLSKI, Z., t o be pub- l i s h e d i n p.s.s, ( a ) .

[3]

Z H ~ T C ~ K ,

T , , SCHNEEWEIS~,

o.,

?roc.

S o f t Mag. Mater. Conf. 3 , B r a t i s l a v a 1977, P a r t 11, p. 748.

neasurement on t h e Fe,Si a b s o r b e r . I t

J

seems t h a t b e s i d e s t h e d i f f u s i o n s a t e , a l s o t h e z a g n e t i c s t a t e of t h e 5 7 ~ o - e n r i - ched t h i n s u r f a c e l a y e r i t s e l f i n f l u e n c e s t h e p r o c e s s v a r y i n g w i t h t h e d e g r e e o f s u b s t i t u t i o n .

[4] NICULESCU, V.9 R A J , K., BUDNICK, J.I., BURCH, T ~ J . , HIRZS, C A . , M ~ O T T I , A.

E., Phys. Rev. B (1975) 4160.

[5] COLLINS, Al.F., FORSYTH, J.S., P h i l . Xag. 8 (1963) 401.

161

MILLICN, B., K U ~ E R A , J., Acta Met, lJ. (i969) 339.

[71 KACN='SON, BOA., POLISHTCHUK, V* Y 5 , , F i z , Met. Metalloved. (1973) 321.