Magnetic behaviour of a stage-1 NiCl2 graphite intercalation compound

Magnetic behaviour of a stage-1 NiCl2 graphite intercalation compound

Synthetic Metals, 34 (1989) 525 ~ 530 52b MAGNETfC BEHAVIOUR OF A STAGE-I NiCI 2 GRAPHITE INTERCALATION COMPOUND M. EL HAFIDI*, G. CHOUTEAU** and ...

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Synthetic Metals, 34 (1989) 525 ~ 530

52b

MAGNETfC BEHAVIOUR OF A STAGE-I NiCI 2 GRAPHITE INTERCALATION

COMPOUND

M. EL HAFIDI*, G. CHOUTEAU** and R. YAZAMI*** *

Universit~ Hassan H, Casablanca

**

Service National des Champs Intenses, Scientifique,

BP 166X,

(Morocco)

38042

Centre

Grenoble

National de la Recherche

C~dex (France)

(Laboratoire

associ~ ~ l'Universit~ Joseph Fourier, Grenoble) *** Laboratoire d'Ionique et drElectrochimie Ecole Nationale

d'Electrochimie

BP 75, 38402 Grenoble C~dex

et

du

Solide

(U.A. CNRS 1213),

d'Electrom~tallurgie

de Grenoble,

(France)

ABSTRACT A

first-stage NiCI 2

powder. the

GIC was prepared using very fine natural graphite

It is shown that three parameters are of importance in determining

stage of

the final

temperature

of the

properties

show

compound

reaction the

: the specific area of the graphite,

and

the

existence

of

chlorine strong

pressure.

The

ferromagnetic

competing with antiferromagnetic ones. The ordering temperature

the

magnetic

interactions is found to

be 17,85 K by ac. susceptibility measurements. INTRODUCTION NiCI 2 sealed

was

first intercalated into graphite by Stumpp et al [i] using a

ampule

studies

at

500°C,

which included

range

395-,oO

C)

crystal

structure

However

in both

under

a

chlorine atmosphere.

the synthesis

and

chlorine

determination

conditions over

pressure were

Further detailed

a wide temperature

(p(Cl2)
reported

by

and also the

Flandrois et al [2].

studies only stage-2 GIC was prepared and has been for a

while considered as the richest NiCI2-GIC. The presence of chlorine gas in the reactor was shown to play a key role in the activation of the reaction As

early

as

1982

[4],

we

[3]. have

shown

that the catalytic effect of

chlorine

during the intercalation of NiCI 2 was enhanced by increasing both

chlorine

pressure

(up

to

iO atm

at

700°C)

and the graphite specific

surface area (<400 m~.g -I ). Under these conditions, stage-i

GIC was achieved.

stage-I and 2 or pure stage-2 or a

grain size are small stage-I

derived This

GIC

using

from benzene

clearly

intercalation

0379-6779/89/$3.50

synthesis of rich

GICs probably

because their specific surface

[5]. Endo et al also succeeded in the synthesis of highly

oriented

decomposition at

emphasizes process.

the

Natural or pyrolytic graphites give mixtures of

the We

role

also

of

graphite fiber of iO00 A diameter 500°C and the

reported

350 tort of p(Cl2)

nature some

of

of the

graphite

[61 .

in the

electrochemical

© Elsevier Sequoia/Printed in Tile Netherlands

526

properties [7].

of the

In this

stage-i NiCI 2

as cathode material

paper we will briefly redescribe

in lithium batteries

the synthesis

stage-i GIC and show some of its structure characteristics properties

compared

with

those

previously

reported

conditions

of

and the magnetic

on the stage-2 one

[8-10].

EXPERIMENTAL With

the aim of checking the effect of the graphite origin on the final

products under week

after the intercalation,

different

graphites were allowed to react

the same conditions i.e. iO atm of chlorine at 7OO°C, during one : I) fine powder (3 ~m) of high specific surface area (400 m2.g -1 ),

obtained

by vacuum

Carbone

Lorraine.

100-150

~m

(FPHS), provided

by le

2) Natural graphite from Ceylan with granulometry

grinding of

in the

range.

3)

natural graphite

Natural

flakes

from

Madagascar

(>.3mm).4)

(7×7×.4 mm 3) provided by Union Carbide. The amount of anhydrous calculated to obtain the molar ratio C/Ni-3.5. After

the reaction,

sifting. HCI

The excess

solution,

dried High

different

at 80°C.

water and methanol.

The structure Electron

The magnetic measurements coil.

Static

by successive

(HREM,

in a dilute

The final compound was vacuum

was determined

Microscopy

The composition was determined by elemental ducting

were separated

NiCI 2 was removed by washing successively

distilled

Resolution

graphites

HOPG

NiCI 2 was

by X-Ray Diffraction

and by

i Mev) for the finest powder. analysis of C, Ni and CI.

were performed at SNCI using a 13 T supercon-

and

dynamic

susceptibility

measurements

were also

performed.

RESULTS and DISCUSSION i. GIC characterization From

XRD analysis

:

(Cu, K~) it was clearly shown that only FPHS graphite

led

to stage-i

GIC whereas

size

to reach

approximately

chart

obtained

with

FPHS

the amount of stage-2 IOO with

% in

the HOPG.

typical

OO1

increases with the grain Fig. i displays

lines

giving

the XRD

an identity

parameter in the c-direction (interlayer spacing) Ic = 9.37 A. The broadening of the strongest 002 line at higher angles should be due to some stacking defects of the NiCI 2 domains. The chemical analysis of this compound leads to a rough formula C~. 9 NIC12.35 which implies a filling factor of 70 % close to that of stage-2 [2]. The larger departure from stoiehiometry in this GIC (CI/Ni - 2.35) is directly related with the higher chlorine cointercalation when FPHS and high chlorine pressure were used. However, if the Flandrois's islandic model [2 - II] is applied, the calculation of the island size from the CI/Ni ratio would give 35 - 40 A. This was not observed in our sample by the HREM lattice image depicted in fig.2-a.

527

002

2e

30

001

10

20

Fig. I X-ray diffraction (Cu, K) chart of stage-i NiCI2-GIC. The calculated lattice constant in the c-direction gives Ic=9.37 ~.

Fig. 2 a) High resolution electron microscopy lattice image NiCI2-GIC, some stacking defects show a random presence compound, b) 001 spots obtained by electron diffraction NiCI2-GIC.

This

optical

NiCI 2 side.

graphite A

of the as

for

determined NiCI 2 not

uses the

001 spots

of fig.2-b

stage-i stage-2 stage-I

and shows the

stacking along the c-axis. The stage number is indicated on the left Some stage-2 domains remain in the GIC which is consistent with the

broadening 12.6

interferogram

of of of

002 line in the XRD chart in fig.l. Taking the pristine

internal stages by XRD.

domains which exclude

the

reference, I

and

We did

2

the calculated

respectively,

not clearly

Ic values were 9.2 and

slightly

lower

would result from small size islands.

presence of

than those

notice any discontinuities

some Ni z+ vacancies

in the

Therefore we do

inside the NiCI 2 domains

(or islands) to explain the excess of chlorine. The in-plane crystal structure is determined from the electron diffractogram. NiCI 2 and graphite hexagonal superlattices are shifted by an angle of 30 degrees, which is in agreement with the XRD data [2 ° 12]. So the calculated lattice parameter a of NiCI 2 is found here equal to 3.50~_.O5 A.

528 2. M a g n e t i c m e a s u r e m e n t s Figure

3 shows

the m a g n e t i z a t i o n

curve o b t a i n e d at 4.2 K in a m a x i m u m

f i e l d of Ii teslas. The f e r r o m a g n e t i c b e h a v i o u r the

magnetization

saturation lity.

can

be

written

m a g n e t i z a t i o n and

Xh~

as

a

is obvious

M = M s + Xh~ .H

: above 3 teslas where

Ms

is the

s u p e r i m p o s e d p a r a m a g n e t i c susceptibi-

One finds M s = 8520 emu / mole c o r r e s p o n d i n g to an average m o m e n t of

1.53 lab per n i c k e l atom. On the other h a n d Xh f = .01076 emu / mole w h i c h is a

v e r y h i g h v a l u e w h e n c o m p a r e d w i t h the usual h i g h field s u s c e p t i b i l i t i e s

of t r a n s i t i o n metals.

413 J E al

30 Z

l-n-

213

i--I I-LIJ Z CO n-

10

NiC]

]s~

STAGE

2 T = 4.2

i

0

i

2.5

i

5.13

MRGNETI£

K

i

ZS F/ELI]

~ O.D IT]

Fig.

3 H i g h f i e l d m a g n e t i z a t i o n at T - 4.2 K in emu/g.

The

low f i e l d

above

50

K,

m o m e n t ~e~f The

static s u s c e p t i b i l i t y where

C,

the

obeys the

Curie constant,

law, Xs t = X o + C/(T - 8)

c o r r e s p o n d s to the e f f e c t i v e

= 3.7 ~ , 0 = 41.5 K and Xo = Xh f .

average and

effective moments

are smaller

than those of Ni z+

(5 and

5.59 r e s p e c t i v e l y ) . On

figure 4

(2

mT

smaller

and

we have r e p o r t e d the static s u s c e p t i b i l i t y in v e r y low fields .5

magnetization and

mT)

than the

a r o u n d 20

decreases

measured maximum

below

in the

30

field c o o l e d

slightly

K. The with

K. The zero f i e l d c o o l e d s u s c e p t i b i l i t y is one s h o w i n g

the

appearance

of a r e m a n e n t

m a x i m u m in X, t occurs at T N = 17.5 ± the

applied

.5 K

field. The ac. s u s c e p t i b i l i t y

f r e q u e n c y range iO Hz - 52 kHz exhibits a w e l l p r o n o u n c e d

at T - 17.85 K, independent of the f r e q u e n c y and in g o o d a g r e e m e n t

w i t h the static measurement.

529

N~CI

%

.ls-t

2

STFIGE

120

E

6g



XZ

:~

311

x CD

0

i

0

i

5

i

10

i

"20

15

TEMPERATURE

[K]

Fig. 4 Static s u s c e p t i b i l i t y per gram. in two fields showing the m a x i m u m a r o u n d T - 17,5 ± 0.5 K and the r e m a n e n t m a g n e t i z a t i o n near 20 K.

The i)

0.5 mT and 2 mT appearance of the

low m a g n e t i c m o m e n t s and the h i g h Xh f c a n be i n t e r p r e t e d in two ways The c r y s t a l - f i e l d

pristine. GIC.

O n l y the

s p l i t t i n g is lowest levels

Thus Xo a n d Xh f

upwards ii

A

25

curvature

teslas,

case

ii)

or

:

d i f f e r e n t in the NiCI 2 GIC than in the are o b s e r v e d

at low t e m p e r a t u r e in the

are v a n V l e c k terms. T h e r e f o r e one s h o u l d observe an a

The NiCI 2

of the MCI 2 GICs, and

transition

in

layers have

the

magnetization

well

a m e t a l l i c character,

above

as it is the

thus the nickel m o m e n t is r e d u c e d w i t h respect

to

the ionic

one b e c a u s e of the c o n t r i b u t i o n of the c o n d u c t i o n electrons.

In

this case

X o (or Xhf)

results

is also

u n u s u a l l y h i g h v a l u e of Xh~ , however, R e c e n t results of

ref.

explain

13

the c o n d u c t i o n

between

electrons.

Our

case i) and case ii). The

favors case i).

(13) do not agree well w i t h ours. We think that the c o m p o u n d

p r o b a b l y consists

w h y the

authors find comparison with

in a m i x t u r e of stage-i and stage-2 and may an o r d e r i n g

than

ours. The

(15),

(16), shows that, as expected,

increase

due to

do not a l l o w for a d i s t i n c t i o n

t e m p e r a t u r e T N = 22.5 K h i g h e r

the p r o p e r t i e s of stage-2 compounds

of the interlayer distance.

(14),

T N decreases w i t h the stage due to the For instance we find T N = 17.85 K for

the s t a g e - i and T~ - 16.5 K for the stage-2.

530

ACKNOWLEDGEMENTS One of us (YR) wishes to thank Dr. Audier (LTPCM, Grenoble) for his help in the HRME experiments and numerous discussions, Dr. Maire from Carbone Lorraine for providing FPHS graphite and Prof. P. Touzain (S2MC, Grenoble) and Prof. A. Hamwi (Clermont-Ferrand) for stimulating discussions concerning NiCI2-GICs. R. Tur has done the magnetic measurements. REFERENCES [i] [2] [3] [4]

[5] [6]

[7] [8] [9] [I0] [ii] [12] [13]

[14] [15] [16]

E. Stumpp and E. Werner, Carbon, 4 (1966) 538. S. Flandrois, J.M. Masson, J.C. Rouillon, J. Gaultier and C. Hauw, Synthetic Metals, 3 (1981) i. W. Rudorff, E. Stumpp, W. Spriessler and W.F. Siecke, Angew. Chem., 75 (1963) 130, L.B. Ebert, Annu. Rev. Mater. Sol., (1976) 181. R. Yazami, Ph. Touzain, M. Audier and L. Bonnetain in the annual meeting of Groupe Franqais d'Etude des Carbones (GFEC), Bonbannes (France), Sept. 13 - 17 (1983). R. Yazami, thesis Grenoble University, (1985), unpublished. M. Endo, G. Timp, T.C. Chieu, M.S. Dresselhaus and B.S. Elman, Phys. Rev., B28 (1983) 6982 and M. Endo in Proceeding of Science and New Applications of Carbon Fibers, Intern. Meeting, Toyohashi University of Technology 19 - 21 Nov. (1984) 77. R. Yazami and P. Touzain, Solid State lonics 9 - IO (1983) 489. Yu. S. Karimov. Soc. Phys. JETP 41 (1976) 772 and Yu. S. Karimov and Yu. Novikov, JETP Lett. 19 (1974) 159. Y. Murikami, M. Susuki and H. Ikeda, J. Magn. Magn. Mater., 31 - 34 (1983) 1171. I. Oguro, M. Suzuki and H. Yasuoka, Synthetic Metals, 12 (1985) 449. S. Flandrois, A.W. Hewat, C. Hauw and R.H. Bragg, Synthetic Metals 7 (1983) 305. C. Hauw, J. Gaultier, S. Flandrois, O. Gonzalez, D. Dorignac and R. Jagut, Synthetic Metals 7 (1983) 313. J.T. Nicholls, J.S. Speck and G. Dresselhaus. MRS Fall Meeting, Boston M.A. Nov. 1988 (USA). Extended abstracts. Ed : M. Endo, M.S. Dresselhaus and G. Dresselhaus. M. Elahy, C. Nicolini, G. Dresselhaus and G.O. Zimmerman, Solid State Commun 41 (1982) 289. M. Suzuki, H. Ikeda, Y. Murakami, M. Matsuura, H. Suematsu, R. Nishitani and R. Yoshizaki, J. Magn. Magn. Mater. 31 (1983) 1173. H. Suematsu, R. Nishltanl, R. Yoshizaki, M. Suzuki and H. Ikeda, J. Phys. Soc. Jpn. 52 (1983) 3874.