The preparation and lattice parameters of CfF4

INORG.

NUCL.

CHEM.

LETTERS

Vol. 9,

pp. 869-874,

1973.

Pergamon

Press.

Printed

in

Great

Britain.

THE PREPARATION AND LATTICE PARAMETERS OF CfF 4 R. G. Haire

and L. B. Asprey t

Introduction (Received 19 A ~ i l 1 ~ 3 )

The t e t r a f l u o r i d e s lattice

parameters

the series

a r e known f o r t h e a c t i n i d e s

have been summarized[l].

Since these

tetrafluorides

patterns

and i n f o r m a t i o n

in order

to calculate

discusses

lattice

o f CfF 4 e x t e n d s

of the tetravalent

state

b e e n o b s e r v e d i n t h e compound Cf0212 ] .

work by A s p r e y on a m i c r o g r a m s c a l e

letter

The p r e p a r a t i o n

t h r o u g h Cf and c o n f i r m s t h e e x i s t e n c e

f o r C f , w h i c h has p r e v i o u s l y

from Th t o Bk and t h e i r

had i n d i c a t e d

have a monoclinic

the

structure,

on t h e a t o m i c p o s i t i o n s

the best

lattice

the preparation

existence

of CfF4[3 ] .

good d i f f r a c t i o n

in the crystal

parameters

Earlier

are necessary

f r o m t h e powder d a t a .

o f CfF 4 and r e p o r t s

the values

This

for its

parameters. Experimental

Materials The 249Cf u s e d i n t h i s

s t u d y was made a v a i l a b l e

through the Trans-

p l u t o n i u m E l e m e n t P r o g r a m o f t h e U.S. Atomic E n e r g y Commission. methods used in the separation reported[2,4]. thanides

The p u r i f i e d

and p u r i f i c a t i o n Cf p r o d u c t

contained

and was >99.8 atom % p u r e w i t h r e g a r d

The CfF 4 was p r e p a r e d CfF3, o r Cf203.

by f l u o r i n a t i o n

The h y d r a t e d

a q u e o u s HC1 s o l u t i o n

CfC13 s a l t

o f Cf t o d r y n e s s ;

of the material

The have been

<0.02 atom % o f t h e l a n -

to the total

cation

content.

o f 10 t o 100 gg o f CfC13"XH20 , was o b t a i n e d

by e v a p o r a t i n g

t h e CfF 3 was p r e p a r e d

an

from an a q u e o u s

* R e s e a r c h s p o n s o r e d by t h e U . S . Atomic E n e r g y Commission. Oak R i d g e N a t i o n a l L a b o r a t o r y , Oak R i d g e , T e n n e s s e e 37830. Operated for t h e U.S. Atomic E n e r g y Commission by Union C a r b i d e C o r p o r a t i o n . Author was a g u e s t a t t h e Los Alamos S c i e n t i f i c Laboratory for the experimental work. qLos Alamos S c i e n t i f i c L a b o r a t o r y , Los Alamos, New Mexico 87544. f o r t h e Atomic E n e r g y Commission by t h e U n i v e r s i t y o f C a l i f o r n i a .

869

Operated

870

L A T T I C E PARAMETERS

solution by precipitation with HF.

Vol. 9, No. 8

The Cf205 used in the experiment was

produced by calcination of californium oxalate at 700-800°C.

Several TbF 4

preparations were also made as controls, using the same experimental conditions used for making CfF 4 but employing Tb407 and TbF 3 as starting materials.

In some cases, TbF 3 was fluorinated simultaneously with the

CfF 3 samples.

All fluorinations were carried out in nickel equipment with

the sample being contained in a sapphire dish.

Similar equipment has been

described[5,6]. The best tetrafluoride products were obtained when the starting materials were TbF 3 or CfP 3.

The tetrafluoride prepared from Cf203, Tb407, or the

hydrated CfCI 3 were generally less crystalline than products from comparable fluorinations that started with CfF 3 or TbF 3.

The effect of longer

fluorination times on the product prepared from the oxides or chloride salts was not investigated.

For preparing CfF4, the fluorination of the

starting materials was carried out at S arm. of F 2 at 400 to 450°C for a period of 2 to 3 days. the products were CfF 5.

At 200 to 550°C or with fluorination times of ~I day In contrast, a temperature of 550°C was adequate to

prepare TbF 4 from Th407 or TbF 5.

This difference in ease of preparation

between TbF 4 and CfF 4 may reflect differences in the III-IV oxidation potentials for the two elements.

After fluorination at the elevated tempera-

tures, it was customary to cool the product in the F 2 atmosphere to ambient temperature and then purge it with argon.

The resulting products were

removed from the dishes and loaded into X-ray capillaries in an argonatmosphere glove box to avoid exposing the products to air or moisture. Data Analysis X-ray powder diffraction films were obtained from conventional DebyeScherrer cameras, having 57.5 and 114.6 mm diameters, using copper radiation and nickel filters. averaged.

The films were read by two observers and the readings

The lattice parameters were refined by the LCR-2 computer pro-

gram[7] using the Nelson-Riley correction.

The theoretical line intensities

Vol. 9, No. 8

LATTICE PARAMETERS

were calculated positions

with the aid of the

reported

for

UF419].

motion or absorption. The l a t t i c e using for lines

parameters

approximate

CfF4;

this

mentally. weighted

assignments

at that

indices

in cases

When m u l t i p l e on the basis

h a d t o be a t

least

particular

of its

produced

a green

with monoclinic

o f CfC13,

calculated

was g e n e r a t e d lower angle

The s e c o n d s t e p

theoretical

line

experimental

data,

were n o t

intensity;

First,

list

experi-

each assignment to be included, for

which

using

separated

intensity

was

all

was it

assigments

and Discussion Cf203,

o r CfF 3 w i t h 3 a t m . o f F 2 a t 400 t o 450°C

The c r y s t a l l i n e

o f t h e CfF 3 p r o d u c t s

This is

was i s o s t r u c t u r a l

by X-ray diffraction,

shewed o n l y a n o r t h o r h o m b i c

in agreement

who h a v e r e p o r t e d

and a high temperature

material

space group C2/c[9].

this

The a v e r a g e

list

to severaI

were employed,

calculated

CfF 4 p r o d u c t .

up t o 450°C,

Peterson,

lines

deviation.

angIe.

at temperatures compound.

where the

15% o f t h e t o t a l

UF4 ,

Examination

another of the

thermal

fashion.

line

indices

to all

assignments

Results Fluorination

in a two-step

was c a l c u l a t e d .

to generate

the atomic

are one standard

CfF 4 , a t h e o r e t i c a l

of parameters

new p a r a m e t e r s

was t h e n u s e d t o a s s i g n multiple

for

using

were made f o r

reported

was t h e n u s e d t o a s s i g n

f r o m w h i c h a new s e t

to use these

limits

were calculated

parameters

list

POWD p r o g r a m [ 8 ] ,

No c o r r e c t i o n s

The e r r o r

871

with the results

a low t e m p e r a t u r e

trigonal

structure

room t e m p e r a t u r e

for

lattice

after

heating

structure

of Stevenson

(~600°C) o r t h o r h o m b i c

for and structure

CfF3[10 ] .

parameters

obtained

o

from seven o

samples of CfF 4 were a ° = 12.425 ± 0.004 A, b ° = 1 0 . 4 6 8

+_ 0 . 0 0 4 A, c o =

o

8.126 ± 0.003 A, and ~ = 126.02 ± 0.02 ° .

These dimensions yield a

o

molecular volume of 7 1 . 2 1 A 3 for CfF 4. preparations is given in Table i.

The line list for one of the CfF 4

The average lattice parameters obtained o

o

for CfF 3 were a ° ~ 6.660 _+ 0.008 A, bo ~ 7.032 ± 0.007 A, and Co = 4.397 _+ O

0.007 A, in good agreement with the values previously reported for CfFs[10,11 ]

872

LAT11CE PARAMETERS T a b l e 1.

h

k

1

observed

26. calculated a

11•

21.70 21.76 23.20 24.53 24.56 25.82 27.83 27.97 34.16 34.29 54.39 34.61 35.74 37.42 38.79 39.22 40.12 42.31 42.40 43.95 44.18 44.35 44,79 43.02 46.96 47.50 47.31 48.17 48.19 48.23 48,78 48.99 49.49 49.86 49.91 50.79 51.~1 52.55 S4.20 54.39 54,5S 55,62 55.77 57.77 57.80 57,82 58.Sl 50,87 59,72 61,28 61,30 61,65 62,40 63,05 63.76 63.89 64.24 64.27 65.08 65.65 66.02 66.09 67.09 67.68 67.75 68.05 68.95 68.97 69.08 69.62 70.53 70.75 71,34 71.59 72.26 72,27 72.53 73.01

21.94

-

3

-

1

i] ::2

2 -

2 1 0

5 1 3

}] 49

-4 -

3

-

1 l 4

-

2

25.99 27.49 27.98

2 0

2

i ]

34,90 36.3O 33::40:

-4 -

40.3O

S 3 1

-

3 ]

43.71

6 1

2 ~

2 2 -

42.55

44.4I 44.80 45.29 47.I1

1

2 -9 -5

47.40 4

48.47

1 -6 - 3 4

49.00

- 1 -4 -6

49.71

6

50.15 50.87

1

51.45

S 2

52.66

-

0 1 7

-

o ' ] 5 ....

2 -

!] .....

1

7 4 7 0 4

-4

5

-6 S -

8

1 3

1

4

2 8

11-

5 -

2 4 1

2

0 O

65,19 65.69

4

13

6613

2

66.93

O

!]67.98 i] .....

6

~]

7

~l

.....

~J

.....

1 3 7

- 4 -9

3 -9 -6 - 8

-6 4 -6 -

1 7

-

9

2

61.81 62.59 63.06

6

7

-

59.73

~] 0 1 .

6 3 2

69.53 70.66 70.97

.....

L i n e L i s t and I n d e x i n g f o r M o n o c l i n i c CfF 4

rnte~slty observed b calculated c

26_ h

10.00 4.33

S S S

intensities

~ MM WW-

W F F F

W W ~ W

W M W M W N F F W ~ N F* T F

W

2

6]

T F F+ T

W w

T W P F W F

lattice

1

73.39

(S). aediua

(~.

2

3

I

i

74,47 75.94

2!]

78.53

8

21

:]

70.34

7

4

81.00

8

o]

5

parameters

05.39

11]

6 6 4

84.73 J

85.94

-11

1

-

0 5

1 /

86.80

4

0

~] 88.17

8 3 7

-

6

8

7

1

4

0

1

8 7

4

6

-6 -10

2

-

3

3

7

4

2

10 2

0 I 0 4

6 5 O 8

-12 -9

0 7

-

S

5

S

0

2

6

-2 -

-

10 0 1 2 -11 5 -6 -8 -

-

0 1O 9 10 5 3 2 3

1

1

9 6

5 4 10 3 O 4 5 7 4 7

4

9 -4 -12 9 7 0 1

09.50 91.09 93.77 04.83 7" 0 l 0 7 0 6

7

8

4

l~

-IS 6 -2

i 6 8

96,04 97.29 98.32

8"

2 6 47" 0 6 02

3-

99.24

100.04

101.09

1_

101.36

4_

102.05

~

27 0_ 3 31

~

_

7 _

102.86 103,06 105.80 116.17 121.03

6131.44 133.44

7

11

-13 -14

3 4 13 1

-

-

3

5

I]138.6o 142.54 5" 9 3. 1

146.95 154.36 158.09

Intensit~

calculated a

observed b

F F

0.29

F F

0.18 0,42 0.51

77.40

W

0.37

77.60 78,28 78,56 78.69 79.31 79.55 80.93 83.24 83,40 84.92 05,00 85.13 89+81 86.30 86.83 87.03 87.00 88.07 88.50 89.63 89,67 91.05 93.85 94.57 94.98 96.07 96.21 97.10 97,55 08.09 98.27 98.34 99.13 99.28 99.33 99.40 99.88 99.94 99.95 100.21 101.19 101.58 101.60 101.32 101.98 102.16 102.65 102.76 102.90 103.01 105.44 105.60 105.67 116.04 116.26 120.93 121.37 131.22 131.31 131.48 135,65 139,54 139.57 142.30 146.68 147.02 147.16 154.47 158,20

=

0.20 0.20

0.62 0.26 0.07 0.I0 0.11 0.20 0.17 0.06

F F FT

0.14

0.2] 0.24

W-

0.19

0.04 0.12 0.16 0.28 0.20 0.16 0.23 0.16 0.19 0.13 0.30 O, 19 O. 07 0.34 0.40 0.07 0.07 O,O9 O.OS 0.03 0.23 0.26 0.22 0.47 0.20 0,24 0.18 0.24 0.03 0.20 0.36 0.21 0.39 0.10 0.12 0.13 0.13 0.07 0.31 0.3O 0.12 0.03 0.06 0.39 0.37 0.10 0.13 0.11 0.35 0.15 0.10 0.14 0.67 0.56 0.43 0.37 0.55

T F F F ~ T p T T F

F T F F F F 8T F T F F T WT F

(F). and trace

calculated

(T).

no c o r r e c t i o n s

for

the

w e r e Bade f o r t h e r l m l

monoclinic

o

obtained in this work were a °

calculated c

73.34 73.43 73,02 73.96 74.50 76.30

With ~(~) - 1.54178 A,

weak (W). f a i n t

C C a l c u l a t e d u s i n 8 t h e POND i n t e n s i t y p r o g r a a s c a l e d so t h a t t h e O 2 1 l i n e h a d I - I 0 . 0 ; absorption. Based on t h e IYF4 s t ~ c t u ~ . ~ o n o c l l n l c Spac~ g r o u p C 2 / c .

The a v e r a g e

observed

1

0.70 0.28 0.25 0.68 0.S5 0.14 0.52 0.38 0.49 0.09 1.13 0.94 0.72 0.34 0.48 0.43 0.04 0,57 0.36 0.27 0,33 0.47 0.38 0.26 0.29

W

of strong

l

6,

0.13

T W-

on b a s i s

k

8.15 4,88 7.77 6.00 $.86 3.60 1,43 1.40 1.06 0.70 0.80 1.07 0.36 0.21 0.33 0.23 0.20 1.94 0.74 1.97 3.64 3.52 1.48 0.40 0.53 1.95 1.20 1.92 1.$9 0,99 1.97 1.90 l.ll 0.76 0.54 0.43 0.26 0.72 0.26 0.30 0.37 0.29 0.43 0.81 0.41 0.40 0.10 0.12 0.24 0.99

aCalculated usin 8 so • 12.42 ~, b° - 10.47 A, co - 8,13 ~, and B - 126.0. bEstigmted relative

Vol. 9, No. 8

12.109 ± 0.006 A, b °

lotion

or

TbF 4 o

=

10.142 ± ~.00S A,

o

co

=

7.928

essentially

± 0.003

A, a n d

identical

to

B = 126.14 those

in the

+ 0.03 ° , and these

values

are

literature[12].

Conclusion The preparation of CfF 4 and the previous work on Cf0212 ] show that

Vol. 9, No. 8

L A T T I C E PARAMETERS

tetravalent for

Cf c a n b e o b t a i n e d

CfF 4 show t h a t

of Th-Bk.

this

in the

compound i s

solid

873

state.

isostructural

The p o w d e r d a t a

obtained

with the tetrafluorides

However, after obtaining the lattice parameters for CfF4, it

was evident that the values reported for BkF4[13 ] were inconsistent with the lattice dimensions for the other actinide tetrafluorides.

Haug[14]

had noted earlier that there were some discrepancies between the lattice parameters for BkF4[13 ] and the values for the previous numbers of the series.

Recent calculations using additional powder data have generated

parameters for BkF 4 that are more compatible with the values reported here for CfF 4 and values for the other actinide tetrafluorides.

The difference

between the parameters prev'iously reported for BkF 4 and the new parameters referred to here is due mainly to the indexing procedure used for the powder data.

A revised set of lattice parameters for the actinide

tetrafluorides

from Th to Bk has been calculated, using the procedure

outlined in this work, and these values will be published in a separate letter

[15]. Of t h e known a c t i n i d e

oxidize slightly

to the tetravalent more d i f f i c u l t

the experimental

tetrafluorides state;

to prepare

difficulty

Cf i s

and in this t h a n TbF 4.

in obtaining

the most difficult

to

work CfF 4 was f o u n d t o b e This is

in accord with

e l 0 2 o r Tb0 2, w h e r e h i g h p r e s s u r e

02 or atomic oxygen was required to oxidize the lower oxides of these elements to Cf02 or Tb02[16 ].

The behavior of Cf is in contrast to that

of Am, Cm, or Bk, whose dioxides can be easily prepared in air.

The

difficulty in attaining the tetravalent state of Cf and Tb compared to the other actinides from Th to Cf is in accord with the III-IV oxidation potentials calculated for the lanthanides and actinides by Nugent et al.[17]. Acknowledgements The authors wish to acknowledge the helpful discussions with J. H. Burns of Oak Ridge National Laboratory during the preparation of this letter.

874

LATTICE PARAMETERS

Vol. 9, No. 8

References 1.

T. K. Keenan and L. B. Asprey, I n o r g . Chem., 8, 235 (1969).

2.

R. D. Baybarz, R. G. H a i r e , and J . A. Fahey, J .

I n o r g . Nucl. Chem.,

34, 557 (1972). 3.

L. B. Asprey, u n p u b l i s h e d r e s u l t s

(1970); acknowledged i n r e f .

2.

4.

R. D. Baybarz, J. B. Knauer, and P. B. Orr, USAEC Rep. ORNL-4672

(1973). 5.

L. B. Asprey, J. Am. Chem. Soc., 76, 2019 (1954).

6.

L. B. Asprey, F. H. E l l i n g e r , S. P r i e d , and W. H. Z a c h a r i a s e n , J . Am. Chem. S o c . , 79, 5825 (1957).

7.

D. E. Williams, Ames Lab. Rep. IS-I052 (1964).

8.

D. K. Smith, Univ. Calif. Lawrence Radiation Lab. Rep. UCRL-7196

(1963). 9.

A. C. Larson, R. B. Roof, Jr., and D. T. Cromer, Acta Cryst., 17,

555 (1964). 10.

J . N. S t e v e n s o n and J. R. P e t e r s o n , J.

11.

J . R. P e t e r s o n and B. B. Cunningham, J .

I n o r g . Nucl. Chem. ( i n p r e s s ) . I n o r g . Nucl. Chem., 30,

1775 (1968). 12.

D. H. Templeton and C. H. Dauben, J. Am. Chem. S o c . , 76, 5237 (1954).

13.

L. B. Asprey and T. K. Keenan, I n o r g . Nucl. Chem. L e t t e r s , i ,

537

(1968). 14.

H. Haug, K e r n f o r s c h u n g s z e n t r u m , K a r l s r u h e , Germany, p r i v a t e cormnunication.

15.

L. B. Asprey and R. G. H a i r e , t o be s u b m i t t e d t o I n o r g . and Nucl. Chem. L e t t e r s (1973)

16.

D. M. Green, W. C. Koehler, and J. J. Katz, J. Am. Chem. Soc., 73,

1475 (1951) 17.

L. J . Nugent, R. D. Baybarz, J . Nucl. Chem., 3_33, 2503 (1971).

L. B u r n e t t , and J . L. Ryan, J .

Inorg.