H3O+ β″-alumina

Solid State |onics 18 & 19 (1986) 642-644 North-Holland, Amslerdam

642

AN A L T E R N A T I V E

John

O.

FABRICATION

T H O M A S I, G a r r y

I Institute

2Institut

ROUTE

TO H3 O+

J. M c I N T Y R E 2 and J o h n

of C h e m i s t r y ,

University

Laue-Langevin,

38042

3 D e p a r t m e n t of M a t e r i a l s P h i l a d e l p h i a , PA 19104,

Science U.S.A.

DeNUZZIO 3

of U p p s a l a ,

Grenoble, and

uia N H 4 + / H 3 O+ B " - A L U M I N A

~"-ALUMINA

Box

Cedex,

531,

S-751

21 U p p s a l a ,

Sweden

France

Engineering

KI,

University

of P e n n s y l v a n i a ,

It has b e e n n o t e d p r e v i o u s l y that c r y s t a l s of H3 O+ 6 " - a l u m i n a p r o d u c e d by acid exc h a n g e of Na + B " - a l u m i n a in conc. H 2 S O 4 are of p o o r q u a l i t y , w h e r e a s d e a m m o n i a t i o n of NH4+/H30+" B " - a l u m i n a c r y s t a l s by h e a t i n g a p p e a r s to leave the m a t e r i a l in comp a r a t i v e l y good c o n d i t i o n . S i n g l e - c r y s t a l n e u t r o n d i f f r a c t i o n s t u d i e s of b o t h c r y s tal p r o d u c t s have thus b e e n u n d e r t a k e n to e s t a b l i s h the f e a s i b i l i t y of d e a m m o n i a tion of N H 4 + / H 3 O+ B " - a l u m i n a as a r o u t e to H3 O+ B " - a l u m i n a . The final m a t e r i a l s are shown to r e s e m b l e one a n o t h e r c l o s e l y . 2 EXPERIMENTAL

I INTRODUCTION Of the p r o t o n i c investigated, N H 4 + / H 3 O+

B"-alumina

tor of p r o t o n s : rising

network

has

p l a n e 2.

Extending has

composition to b e g i n

remaining

indicate

that

shown

forming

resembles

acid

exchange

by T G A m e t h o d s

a OH-

loss the

group

on

o-measurements falls

6"-alumina

It is thus

produced H3 O+

the

plane;

how closely

of the m a t e r i a l

the de-

approaching

for H30+

t e m p e r a t u r e s 4.

tion

to h i g h e r

the c o n d u c t i v i t y

to k n o w

of the

and H 2 0

that

involves

proceeds;

observed

terest

work

b l o c k 3. R e c e n t

deammoniation

higher

this

indicated

conduction

proton

spinel

ions

in the c o n d u c t i o n

200°C)

the

30°C,

diffrac-

the d e t a i l H3 O+

(earlier

above

of NH 3 from

value

ions,

contained

temperatures

conduc-

200°C I. An

neutron

exposed

the

of

as the

at in-

structure

by d e a m m o n i a -

B"-alumina

TWO

single-crystals

studied

o ~ 7 × I 0 - 4 9 - I c m -I at

of N H 4 +

molecules

the

is the b e s t

single-crystal

study

so far

system

to ~ 2 × I 0 - 2 ~ - I c m -I at

earlier tion

B-/B"-aluminas

the m i x e d - i o n

made

by

from Na + B " - a l u m i n a .

0 167-2738/86/$ 03.50 {D Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)

was

by n e u t r o n

~50+~"-afum~na

of Na + 280°C

~"-alumina for ~24h.

white, The to as

opaque second

here

been The first

made

exchange

by acid

in conc.

The

D 2 S O 4, at

resulting

and h i g h l y crystal

cryS~a(

crystal

wa~

micaceous.

was

that

referred

B in R[f. 5, in w h i c h an

only

partially

made

to d e a m m o n i a t e

na c r y s t a l

have

diffraction.

successful

attempt

was

NH4+/HsO+8"-a~um( -

a

by h e a t i n g

at

300°C

for

3d

in a dry N 2 gas stream. A 22% d e c o m p o + s i t i o n of NH 4 was a c h i e v e d . The same crystal

has n o w b e e n

drastic

treatment:

heating

350°C

for

21d,

250°C

for

3d in one

The

crystal

damaged

data-sets both

followed

was

after

Single

at at

of w a t e r vapour.

and

apparently

un-

heating.

were

crystals;

Grenoble.

in air

by h e a t i n g

atm.

clear

crystal

R2 reactor,

s u b j e c t e d to a more

the

neutron

diffraction

collected

at

the

at S t u d s v i k ' s

first

22°C

s e c o n d on DI0 at the

The d a t a

were

treated

for

ILL,

as de-

J.O. Thomas et al. / Alternative fabrication route to H3 O+ (3"'-alumina in R e f .

scribed

2.

Heat treated striking

3 RESULTS

D50 + B"-a~umina:

No

previous

dy has

been

successful

detail

of the H - b o n d

had

n e u t r o n stu-

in c l a r i f y i n g

be

the

at

positions terium

Neither

could

be r e s o l v e d ,

attached

the d e c o m p o s i t i o n occupied

Again,

synthesis

sites

corresponding

The

only

could

synthesis

at m i d - o x y g e n

of the

ment

(03-D6:

Fig.

1(a).

1.01(4)

spinel

to OX and

from

H6

from

tent

at

be r e s o l v e d .

of the

z=~

in the H - b o n d A Fourier

conduction-plane

is g i v e n

Fig.

in

03 - H6 d i s t a n c e

con-

1(b).

was

The

here 0.92(8)A.

conduc-

after

z=~ c a l c u l a t e d

of OX and D6

to the

5. No f u r t h e r d e t a i l

scheme

similarity

between

the

the two p l o t s

inclusion

could

conduction

(AII - 4; O1 - 5) was

The q u a l i t a t i v e at

+

significant

in a d d i t i o n

atoms

Ref.

to 03 a f t e r

of NH4 + ions.

of the c o n t e n t

plane

the

the o n l y

block

refined tion

- n o NH 4

in

+

for a deu-

to OX of Ref. 5. A F o u r i e r

corresponding

sites

NH 4

to the H6 of

itself

site was

6c

The

all

that

the D - a t o m

except

atom corresponding

Ref. 5 w h i c h other

here

was

in H 3 0 + B "scattering

-alumina.

here

decomposed

now been

plane. network

NH4+/H3 O+ ~ " - a l u m i n a :

result

found

643

is s t r i k i n g ,

and w o u l d

suggest

in the r e f i n e -

A)

is g i v e n

that

an H3 O+

deed

been

5"-alumina

crystal

has

in-

in

¥

\

formed

by d e a m m o n i a t i o n

of

¥

,

\

t

05 \

:,

r3

05

o

r-.

o

I ,

I

I

(a)

Fig.

I

Observed Z

Fourier

= ~I in:

Contour

(b)

(a)

synthesis

D3 O+

interval:

of

the

B"-alumina;

arbitrary

units

content (b) (the

of

heat same

the

conduction

treated in both

N H4+/H30+ plots).

plane

at

~"-alumina.

\

J.O. Thomas et al. / Alternatiw, ]dbrication route to H30 + (3"-alumina

644 +

+

NH 4 /H30 by the

~"-alumina.

similar

occupations

refined

(Table

cupations

will

error

to the

due

of a d d i t i o n a l also,

O X a n d H6

be q u a n t i t a t i v e l y

H

in all

is s u p p o r t e d (D6)

I ).Note t h a t all

absence (D)

centrosymmetry

assumed

This

in the

scattering

(R3m)

oc-

in

Th~s

Crystal

(NFR),

Department

power;

OX

+

D30

~"

D6

OX + ~NH 4 /H30 B" H6 (heated)

y,

z

has b e e n

No. per form. unit*

0, 0.1255(10)

I/3,1/6,1/6 0,

of

Research

UnZted

Energy

States

Council' b{! ~hc

(DOE).

I

G.C.

Farrington,

K.G. F r a s e and T h o m a s . In Advanaes [n Mate~iafs Science, 1984.

J.O.

I/3,1/6,1/6 0,

Science

~z t h e

Ln Sw¢d~,;~

REFERENCES

refinements.

x,

and

supported

model

Parameters refined for OX and H6 (D6) in the two crystals studied.

Atom

been

by the Na~ura~

2

Table I

worh~ has

0, 0.1226(24)

0.84(16) 0.31(8) 0.92(11) 0.48(16)

*Ideal form: X5/3 Mg2/3 A1101/3017.nH20

J.O. Ac%a

Thomas

C,~ys¢.

a n d G.C. F a r r i n g t o n . B59 (7983) 227.

3

J.O. T h o m a s , K.G. F r a s e , G.J. M c I n t y r e a n d G.C. F a r r i n g t o n . So£,~d S¢a¢(' Ionic,, 9/10 (1983) 1029.

4

J.

5

J.O. K.G.

DeNuzzio.

To be p u b l i s h e d .

T h o m a s , G.J. M c I n t y r e and F r a s e . In SoC.{d S~ata P~o~o~{c C o n d u a t o ~ , Vol. III. Eds. J.B. G o o d e n o u g h , J. J e n s e n and A. P o t i e r . O d e n s e U n i v e r s i t y Press.