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The preparation of berkelium tetrafluoride and its lattice parameters (1)
INORG.
NuCL.
CHEM.
LETTERS
Vol.
4, pp.
537-541, 1 9 6 8 .
Pergamon
Press.
Printed
In
THE P R E P A R A T I O N OF BERKELIUM T E T R A F L U O R I D E AND ITS L A T T I C E P A R A M E T E R S (1)
L. B. A s p r e y and T. K. Keenan Los A l a m o s S c i e n t i f i c L a b o r a t o r y , U n i v e r s i t y of C a l i f o r n i a , Los A l a m o s , New M e x i c o 87544 (Recelved24 June 1968)
F O R s o m e y e a r s i t h a s b e e n known that t e t r a v a l e n t b e r k e l i u m can be f o r m e d in s o l u t i o n (2); h o w e v e r , the only known s o l i d compound c o n t a i n i n g Bk(IV) i s the d i o x i d e , BkO 2 (3, 4).
N u m e r o u s compounds
containing Bk(III) a r e known ( 4, 5). M i c r o g r a m q u a n t i t i e s of 24SBk b e c a m e a v a i l a b l e r e c e n t l y through the h e a v y e l e m e n t p r o g r a m of the U. S. A t o m i c E n e r g y C o m m i s s i o n . T h i s l e t t e r r e p o r t s the p r e p a r a t i o n of b e r k e l i u m t e t r a f l u o r i d e f r o m s o m e of this m a t e r i a l . The p r o b l e m w a s t w o - f o l d .
F i r s t , p u r i f i c a t i o n of the 24SBk on a
microgram scale was necessary;
in p a r t i c u l a r , the s e p a r a t i o n f r o m
c e r i u m w a s i m p o r t a n t a s c e r i u m follows b e r k e l i u m ( I V ) c h e m i s t r y f o r the m o s t p a r t .
The p u r i f i c a t i o n w a s c a r r i e d out u s i n g the techniques
d e v e l o p e d at B e r k e l e y b y Cunningham' s group ( 4 ) .
Scrupulous care
was n e c e s s a r y to avoid c o n t a m i n a t i o n by e i t h e r r e a g e n t s o r c o n t a i n e r s . A c o m b i n a t i o n of d i l u t e HC1 c o l u m n s , 20 p e r cent e t h a n o l - s a t u r a t e d HC1 c o l u m n s , and s o l v e n t e x t r a c t i o n of Bk(IV) by d i - 2 - e t h y l h e x y l p h ~ , ~!'(~ic a c i d w a s u s e d for p u r i f i c a t i o n .
The only d e t e c t a b l e impurities: i,: ;!~e
537
Great
Britain.
538
BERKELIUM TETRAFLUORIDE
final p r o d u c t as shown by s p e c t r o s c o p i c a n a l y s i s w e r e Mg = 14, C a = 14,
Sr=0.14,
and Ba = 0. 44.
C e w a s reduced f r o m > 2 0
atom p e r c e n t to l e s s than a d e t e c t a b l e a m o u n t (14). The s e c o n d p a r t of the p r o b l e m was the p r e p a r a t i o n of a m i c r o g r a m q u a n t i t y of BkF 4 in a f o r m s u i t a b l e for use with X - r a y powder t e c h n i q u e s .
Some y e a r s ago C u n n i n g h a m , et al (6, 7)
found that a s i n g l e r e s i n bead of i o n - e x c h a n g e r e s i n could be used to c o n c e n t r a t e m i c r o g r a m (or l e s s ) a m o u n t s of an a c t i n i d e i n a form c o n v e n i e n t for m a n i p u l a t i o n or t r a n s f e r . technique to p r e p a r e BkO 2 (3, 4);
They used such a
the b e r k e l i u m - c o n t a i n i n g bead
i n a q u a r t z c a p i l l a r y was i g n i t e d i n a i r o r oxygen and then an X - r a y photograph was taken in the s a m e c a p i l l a r y . The p r o b l e m h e r e was s o m e w h a t m o r e c o m p l i c a t e d s i n c e it was hoped to p r e p a r e BkF 4 by the u s e of e l e m e n t a l f l u o r i n e .
H e r e q u a r t z o r any
r e a c t i v e m a t e r i a l could not be used for a c a p i l l a r y to hold the u n f l u o r i n a t e d bead;
Instead, i t b e c a m e a p p a r e n t that we m u s t
t r a n s f e r the compound BkF 4 a f t e r f l u o r i n a t i o n . U s i n g the analogous l a n t h a n i d e t e r b i u m , we i n v e s t i g a t e d n u m e r o u s m e t h o d s for o b t a i n i n g a d i s c r e t e solid p i e c e of 1 m i c r o g r a m m a s s which could be t r a n s f e r r e d into an X - r a y c a p i l l a r y and s t i l l r e t a i n its f o r m . S u c c e s s was achieved by p l a c i n g a loaded i o n - e x c h a n g e bead of about 1 m m d i a m e t e r i n a s m a l l s a p p h i r e c r u c i b l e ( i n e r t to F 2 at 400*), d r y i n g the bead u n d e r v a c u u m at room t e m p e r a t u r e , then g r a d u a l l y i n c r e a s i n g the t e m p e r a t u r e o v e r the p e r i o d of an hour to about 400°C.
At this point, He gas was i n t r o d u c e d to a t m o s p h e r i c
pressure.
Then a s m a l l a m o u n t ( ~ 0.03 a t m . ) of g a s e o u s
f l u o r i n e was i n t r o d u c e d through a manifold.
Several successive
Voh 4, No. 9
Yol. 4~ No. 9
BERKELIUM TETRAFLUORIDE
539
TABLE I P a r t i a l P o w d e r P a t t e r n s f o r U F 4 and BkF4 BkF 4
UF 4 hk£
d
obs
021,027 111
dcalc
Ist
4.212 4. 193
2o~
4.191
h k £
dob s
0 2 1, 0 21" 7
4. 189
1 1 1
dcalc 4.090
4.075
4.071 4.028
2 0
317
3.936
3.929
7
3 1T
3.832
3.818
22O
3.717
3.712
8
2 2 0
3.616
3. 622
31~ 13T
3.549
3.558
6
3 1
3.450
3. 436
3.292
3.296
7
1 3
3.208
3.211
2.678
112 421"
2. 680
13~
53~ 241
I2 .072
133
2. 672
4 27 2
1 12
2. 609 2.619
2. 608
2. 669
13 2
2. 598
2. 076
2 4 1
2. 032
2. 075
10
2. 074
5 3
2. 013
1 3
2. 027 2.019
53~
1.980
1.977
2
5 3
i . 930
1. 924
62~
1. 938
1. 940
6
6 2 3"
1.886
1. 888
35~
1. 918
1. 916
4
3 5 1"
1. 878
1.877
15~"
1.894
1.894
4
1 5 2"
i . 842
1.852
443-
1.881
1.883
4
443-
I. 828
1.835
402
1. 633
1. 632
1
4 0 2
i . 600
1. 602
370
i . 402
1. 402
4
3 7 0
" 384
1. 376
540
BERKELIUM TETRAFLUORIDE
Vol. 4, No. 9
p o r t i o n s of F 2 w e r e a d d e d at 5 m i n u t e i n t e r v a l s , then the F 2 p r e s s u r e w a s i n c r e a s e d to 2 a t m . f o r 16 h o u r s .
A f t e r cooling, the F 2 w a s
d i s p l a c e d b y He and the d i s h w a s r e m o v e d .
The f l u o r i d e p r o d u c t
r e t a i n e d the s p h e r i c a l f o r m of the o r i g i n a l b e a d with s o m e s h r i n k a g e b u t c o n t a i n e d none of the s u l f o n a t e d p o l y s t y r e n e of the o r i g i n a l ion exchanger.
A s p h e r e , a f t e r g e n t l e t a p p i n g to l o o s e n i t f r o m t h e
s a p p h i r e dish, could b e r o l l e d down into a s h a r p l y - t a p e r e d X - r a y capillary.
T h e c a p i l l a r y w a s then s e a l e d off f o r X - r a y a n a l y s i s .
Conventional Debye-Scherrer cameras,
114.6 m m d i a m e t e r ,
w e r e u s e d with the e x c e p t i o n t h a t a 0 . 3 m i l n i c k e l f i l t e r w a s p l a c e d b e t w e e n the B k F 4 and the f i l m ( 8 ) .
T h i s r e s u l t e d not onty i n
r e m o v a l of the k-/3 l i n e of the c o p p e r r a d i a t i o n u s e d but a l s o in r e d u c i n g the b a c k g r o u n d due to the i n h e r e n t r a d i o a c t i v i t y of 24SBk. T h e r e w e r e two s e p a r a t e p r e p a r a t i o n s w h i c h g a v e good q u a l i t y powder photographs.
T h e s e a g r e e d w e l l w i t h e a c h o t h e r and with
w h a t m i g h t b e p r e d i c t e d b y e x t r a p o l a t i o n f o r B k F 4. A p a r t i a l l i s t of d v a l u e s a l o n g w i t h t h o s e of UF 4 a r e given in T a b l e I.
The t e t r a -
f l u o r i d e was found to b e m o n o c l i n i c , i s o s t r u c t u r a l with UF4, s p a c e group C2/c.
The l a t t i c e p a r a m e t e r s in A a r e :
b0 = 1 0 . 5 8 ± 0 . 0 4 ,
a 0 = 12.47 ~- 0 . 0 6 ,
c o = 8 . 1 7 ~- 0. 05, ~ = 1 2 5 . 9 : ~ 0 . 2
°.
The m o l e c u l a r
03
v o l u m e i s c a l c u l a t e d to b e 72.8 A , j u s t s l i g h t l y s m a l l e r than that of CmF4,
7 3 . 6 .~S ( 9 ) . References
1.
T h i s w o r k w a s s p o n s o r e d b y the U. S. A t o m i c E n e r g y C o m m i s s i o n .
2.
S. G. T h o m p s o n , B. B. Cunningham, G. T. S e a b o r g , J . Am. C h e m . Soc. 72, 2 7 9 8 ( 1 9 5 0 ) .
Vol. 4,. No. 9
3.
BERKELIUM TETRAFLUORIDE
B. B. Cunningham, P r o c . Robert A. Welch Foundation Conference on Chemical R e s e a r c h , VI, Topics in Modern Inorganic C h e m i s t r y ( 1962).
4. J. R. P e t e r s o n , University of California Radiation L a b o r a t o r y Report, UCRL-17875 ( 1967). 5.
D. Cohen, S. Fried, S. Siegel, and B. Tani, J. Inorg. Nuel. Chem. L e t t e r s 4, 257 (1968).
6. B. B. Cunningham, J. Chem. Ed. 36, 32 (1959). 7.
B. B. Cunningham, Mierochem J. Syrup. Set. - S u b m i e r o g r a m Experimentation 1~ 55 ( 1961).
8. J. L. Green, Los Alamos Scientific Laboratory, private communication. 9.
T. K. Keenan, unpublished results.
541
NuCL.
CHEM.
LETTERS
Vol.
4, pp.
537-541, 1 9 6 8 .
Pergamon
Press.
Printed
In
THE P R E P A R A T I O N OF BERKELIUM T E T R A F L U O R I D E AND ITS L A T T I C E P A R A M E T E R S (1)
L. B. A s p r e y and T. K. Keenan Los A l a m o s S c i e n t i f i c L a b o r a t o r y , U n i v e r s i t y of C a l i f o r n i a , Los A l a m o s , New M e x i c o 87544 (Recelved24 June 1968)
F O R s o m e y e a r s i t h a s b e e n known that t e t r a v a l e n t b e r k e l i u m can be f o r m e d in s o l u t i o n (2); h o w e v e r , the only known s o l i d compound c o n t a i n i n g Bk(IV) i s the d i o x i d e , BkO 2 (3, 4).
N u m e r o u s compounds
containing Bk(III) a r e known ( 4, 5). M i c r o g r a m q u a n t i t i e s of 24SBk b e c a m e a v a i l a b l e r e c e n t l y through the h e a v y e l e m e n t p r o g r a m of the U. S. A t o m i c E n e r g y C o m m i s s i o n . T h i s l e t t e r r e p o r t s the p r e p a r a t i o n of b e r k e l i u m t e t r a f l u o r i d e f r o m s o m e of this m a t e r i a l . The p r o b l e m w a s t w o - f o l d .
F i r s t , p u r i f i c a t i o n of the 24SBk on a
microgram scale was necessary;
in p a r t i c u l a r , the s e p a r a t i o n f r o m
c e r i u m w a s i m p o r t a n t a s c e r i u m follows b e r k e l i u m ( I V ) c h e m i s t r y f o r the m o s t p a r t .
The p u r i f i c a t i o n w a s c a r r i e d out u s i n g the techniques
d e v e l o p e d at B e r k e l e y b y Cunningham' s group ( 4 ) .
Scrupulous care
was n e c e s s a r y to avoid c o n t a m i n a t i o n by e i t h e r r e a g e n t s o r c o n t a i n e r s . A c o m b i n a t i o n of d i l u t e HC1 c o l u m n s , 20 p e r cent e t h a n o l - s a t u r a t e d HC1 c o l u m n s , and s o l v e n t e x t r a c t i o n of Bk(IV) by d i - 2 - e t h y l h e x y l p h ~ , ~!'(~ic a c i d w a s u s e d for p u r i f i c a t i o n .
The only d e t e c t a b l e impurities: i,: ;!~e
537
Great
Britain.
538
BERKELIUM TETRAFLUORIDE
final p r o d u c t as shown by s p e c t r o s c o p i c a n a l y s i s w e r e Mg = 14, C a = 14,
Sr=0.14,
and Ba = 0. 44.
C e w a s reduced f r o m > 2 0
atom p e r c e n t to l e s s than a d e t e c t a b l e a m o u n t (14). The s e c o n d p a r t of the p r o b l e m was the p r e p a r a t i o n of a m i c r o g r a m q u a n t i t y of BkF 4 in a f o r m s u i t a b l e for use with X - r a y powder t e c h n i q u e s .
Some y e a r s ago C u n n i n g h a m , et al (6, 7)
found that a s i n g l e r e s i n bead of i o n - e x c h a n g e r e s i n could be used to c o n c e n t r a t e m i c r o g r a m (or l e s s ) a m o u n t s of an a c t i n i d e i n a form c o n v e n i e n t for m a n i p u l a t i o n or t r a n s f e r . technique to p r e p a r e BkO 2 (3, 4);
They used such a
the b e r k e l i u m - c o n t a i n i n g bead
i n a q u a r t z c a p i l l a r y was i g n i t e d i n a i r o r oxygen and then an X - r a y photograph was taken in the s a m e c a p i l l a r y . The p r o b l e m h e r e was s o m e w h a t m o r e c o m p l i c a t e d s i n c e it was hoped to p r e p a r e BkF 4 by the u s e of e l e m e n t a l f l u o r i n e .
H e r e q u a r t z o r any
r e a c t i v e m a t e r i a l could not be used for a c a p i l l a r y to hold the u n f l u o r i n a t e d bead;
Instead, i t b e c a m e a p p a r e n t that we m u s t
t r a n s f e r the compound BkF 4 a f t e r f l u o r i n a t i o n . U s i n g the analogous l a n t h a n i d e t e r b i u m , we i n v e s t i g a t e d n u m e r o u s m e t h o d s for o b t a i n i n g a d i s c r e t e solid p i e c e of 1 m i c r o g r a m m a s s which could be t r a n s f e r r e d into an X - r a y c a p i l l a r y and s t i l l r e t a i n its f o r m . S u c c e s s was achieved by p l a c i n g a loaded i o n - e x c h a n g e bead of about 1 m m d i a m e t e r i n a s m a l l s a p p h i r e c r u c i b l e ( i n e r t to F 2 at 400*), d r y i n g the bead u n d e r v a c u u m at room t e m p e r a t u r e , then g r a d u a l l y i n c r e a s i n g the t e m p e r a t u r e o v e r the p e r i o d of an hour to about 400°C.
At this point, He gas was i n t r o d u c e d to a t m o s p h e r i c
pressure.
Then a s m a l l a m o u n t ( ~ 0.03 a t m . ) of g a s e o u s
f l u o r i n e was i n t r o d u c e d through a manifold.
Several successive
Voh 4, No. 9
Yol. 4~ No. 9
BERKELIUM TETRAFLUORIDE
539
TABLE I P a r t i a l P o w d e r P a t t e r n s f o r U F 4 and BkF4 BkF 4
UF 4 hk£
d
obs
021,027 111
dcalc
Ist
4.212 4. 193
2o~
4.191
h k £
dob s
0 2 1, 0 21" 7
4. 189
1 1 1
dcalc 4.090
4.075
4.071 4.028
2 0
317
3.936
3.929
7
3 1T
3.832
3.818
22O
3.717
3.712
8
2 2 0
3.616
3. 622
31~ 13T
3.549
3.558
6
3 1
3.450
3. 436
3.292
3.296
7
1 3
3.208
3.211
2.678
112 421"
2. 680
13~
53~ 241
I2 .072
133
2. 672
4 27 2
1 12
2. 609 2.619
2. 608
2. 669
13 2
2. 598
2. 076
2 4 1
2. 032
2. 075
10
2. 074
5 3
2. 013
1 3
2. 027 2.019
53~
1.980
1.977
2
5 3
i . 930
1. 924
62~
1. 938
1. 940
6
6 2 3"
1.886
1. 888
35~
1. 918
1. 916
4
3 5 1"
1. 878
1.877
15~"
1.894
1.894
4
1 5 2"
i . 842
1.852
443-
1.881
1.883
4
443-
I. 828
1.835
402
1. 633
1. 632
1
4 0 2
i . 600
1. 602
370
i . 402
1. 402
4
3 7 0
" 384
1. 376
540
BERKELIUM TETRAFLUORIDE
Vol. 4, No. 9
p o r t i o n s of F 2 w e r e a d d e d at 5 m i n u t e i n t e r v a l s , then the F 2 p r e s s u r e w a s i n c r e a s e d to 2 a t m . f o r 16 h o u r s .
A f t e r cooling, the F 2 w a s
d i s p l a c e d b y He and the d i s h w a s r e m o v e d .
The f l u o r i d e p r o d u c t
r e t a i n e d the s p h e r i c a l f o r m of the o r i g i n a l b e a d with s o m e s h r i n k a g e b u t c o n t a i n e d none of the s u l f o n a t e d p o l y s t y r e n e of the o r i g i n a l ion exchanger.
A s p h e r e , a f t e r g e n t l e t a p p i n g to l o o s e n i t f r o m t h e
s a p p h i r e dish, could b e r o l l e d down into a s h a r p l y - t a p e r e d X - r a y capillary.
T h e c a p i l l a r y w a s then s e a l e d off f o r X - r a y a n a l y s i s .
Conventional Debye-Scherrer cameras,
114.6 m m d i a m e t e r ,
w e r e u s e d with the e x c e p t i o n t h a t a 0 . 3 m i l n i c k e l f i l t e r w a s p l a c e d b e t w e e n the B k F 4 and the f i l m ( 8 ) .
T h i s r e s u l t e d not onty i n
r e m o v a l of the k-/3 l i n e of the c o p p e r r a d i a t i o n u s e d but a l s o in r e d u c i n g the b a c k g r o u n d due to the i n h e r e n t r a d i o a c t i v i t y of 24SBk. T h e r e w e r e two s e p a r a t e p r e p a r a t i o n s w h i c h g a v e good q u a l i t y powder photographs.
T h e s e a g r e e d w e l l w i t h e a c h o t h e r and with
w h a t m i g h t b e p r e d i c t e d b y e x t r a p o l a t i o n f o r B k F 4. A p a r t i a l l i s t of d v a l u e s a l o n g w i t h t h o s e of UF 4 a r e given in T a b l e I.
The t e t r a -
f l u o r i d e was found to b e m o n o c l i n i c , i s o s t r u c t u r a l with UF4, s p a c e group C2/c.
The l a t t i c e p a r a m e t e r s in A a r e :
b0 = 1 0 . 5 8 ± 0 . 0 4 ,
a 0 = 12.47 ~- 0 . 0 6 ,
c o = 8 . 1 7 ~- 0. 05, ~ = 1 2 5 . 9 : ~ 0 . 2
°.
The m o l e c u l a r
03
v o l u m e i s c a l c u l a t e d to b e 72.8 A , j u s t s l i g h t l y s m a l l e r than that of CmF4,
7 3 . 6 .~S ( 9 ) . References
1.
T h i s w o r k w a s s p o n s o r e d b y the U. S. A t o m i c E n e r g y C o m m i s s i o n .
2.
S. G. T h o m p s o n , B. B. Cunningham, G. T. S e a b o r g , J . Am. C h e m . Soc. 72, 2 7 9 8 ( 1 9 5 0 ) .
Vol. 4,. No. 9
3.
BERKELIUM TETRAFLUORIDE
B. B. Cunningham, P r o c . Robert A. Welch Foundation Conference on Chemical R e s e a r c h , VI, Topics in Modern Inorganic C h e m i s t r y ( 1962).
4. J. R. P e t e r s o n , University of California Radiation L a b o r a t o r y Report, UCRL-17875 ( 1967). 5.
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