Structure and ionic conductivity of glasses in the ternary systems AgX(X = I, Br or Cl)Ag2OB2O3

Solid State Ionics 9 & 10 (1983) 577-584 North-Holland Publishing Company

577

STRUCTURE AND IONIC CONDUCTIVITY OF GLASSES IN THE TERNARY SYSTEMS~AgX (X =I, Br or CI)-Ag20-B20a Tsutomu MINAMI,

Takumi SHIMIZU and Masami TANAKA

Department of Applied Chemistry, University of Osaka Prefecture, Sakai-Shi, Osaka-Fu 591, Japan Superionic conducting glasses in the ternary systems AgX-AgaO-B203 have been prepared for AgX=AgI, AgBr or AgCI. Glass-forming regions, glass transition temperatures, IR spectra, conductivities and transport numbers of Ag + ions and electrons were determined for these glasses. The glasses were composed of BOa, B04 and B-O-B groups regardless of their compositions, and in addition BO3X groups were shown to be present in the glasses with the Ag20/B203 mole ratio larger than unity. The conductivities, ranging from i0 -z to 10 -7 ~-icm-I at 25°C, showed small difference for glasses in the three systems containing the same amounts of AgX, Ag20 and B203. A structure model explaining the Ag + ion transport is proposed. 1. INTRODUCTION The term "solid electrolytes" or "superionic conductors" usually refers to crystalline solids. Recently, however, a number of new glassy materials called "superionic conducting glasses" have been developed, since glasses with high ionic conductivity were accidentally found by Kunze in the system AgI-AgzSeO~ [i]. If the glass composition is expressed in the form of the systems AgI-AgzO-MxOy, MxOy being an oxide, glasses have been prepared in the systems of MxO g = Bz03, Si02, Ge02, P2Os, VzOs, AszOs, Cr03, Se03 and MoOa [ 2 ] . These glasses are reported to be as conductive as liquid electrolytes [3]. One of the specialties of those glasses is that they usually contain large amounts of AgI, a simple ionic salt, and some of them contain no so-called "glass formers." When AgI is replaced by other silver halides, AgBr or AgCI, glass formation becomes difficult. Among the systexas mentioned above, P205- or BzO3-containing ones are only the two systems in which glasses are formed when AgI is replaced by AgBr or AgCI. In a previous paper [4] it has been shown that the comparison of conductivity among glasses containing different silver halides is very useful for discussing the Ag + ion transpor t in the AgX-AgzO-PzOs glasses (AgX=AgI, AgBr, AgCI). The present paper reports the structure and ionic conductivities of glasses in the ternary systems AgX-Ag20-BzOa (AgX= AgI, AgBr, AgCI), these glasses exhibiting high glass transition temperatures, Tg, among the superionic conducting glasses [5-9]. Glass structure is exam-

0 167-2738/83/0000-0000/$ 03.00 © 1983 North-Holland

ined by the infrared (IR) spectra; the glasses in the composition range with the mole ratio Ag20/BzOa larger than unity are shown to contain structural groups like BO3X, where X links directly with B. Composition dependence of ionic conductivities shows that a part of Ag + ions in glass contribute to the conduction. The ionic conductivities are compared among glasses containing different types of silver halides and a model for the ion transport is proposed on the basis of the results obtained. 2. EXPERIMENTAL Glasses are prepared from the mixtures of AgX, AgzO and B20a in a silica glass tube or ampoule. Temperatures for melting the mixtures were 500-8000C, depending on their compositions. X-ray powder diffractions were measured for all the samples prepared to judge them to be amorphous. The fq values were determined by differential £hermal analysis or differential scanning calorimetry. IR spectra were measured mainly for blown films of glasses; KBr pellet techniques were also used to compare the spectra of films with those of KBr pellets. Ionic conductivities were measured for bulk glasses in an electrically shielded chamber over the temperature range 2003 0 0 K m a i n l y at 1 kHz, and electronic conductivities were determined by,the Wagner d.c. polarization method. The transport number of Ag + ions was measured by the emf and the Tubandt methods. Molar volumes were determined from the densities to estimate Ag + ion concentrations in glass. Further details of the experimental tech-

T. Minami et al.

578

niques have been described 13].

/ Structure

elsewhere

and ionic conductivity o f glasses

[10(a )

6~0 /

3. RESULTS AND DISCUSSION 3.1. Glass-forming

310 1230 103090

region and 2g

Figure 1 shows the glass-forming regions of each system AgX-Ag20-Bz03 (AgX = AgI, AgBr, AgCl). In the figure iso-Tg curves are also shown; the numerals in the figure are Tg values represented in °C. The glass-forming regions are very slightly influenced by the difference in AgX and are very similar in the three systems, Glasses are formed in the compositions with very low content of BzO3, the glassforming oxide, and the glass-forming regions extend to the compositions with the mole ratio Ag20/BzO3 = 3. In the composition region with the low BzO3 content Tg is primarily determined by the Bz03 content and increases with increasing the content. In the region of high B203 content, however, the socalled "boron-anomaly" is observed in each system. The highest value of fg is about 390°C. 3.2.

IR spectra

13101260

/A

0521

~

(e)

~~IO7 o 01 930 ~ A CI 20 80 40 60 60 40 Ag2~0B203

I

I

I

I

1200

I

Figure 2 shows some examples of the IR spectra, which were very slightly affected by the difference in AgX; spectra of blown films of glasses for A g X = AgCI are

I

I

1000

WAVENUMBER

bands

,7°

~ 1040

z <

1400

3.2.1. Absorption

950

020

z o

(

I

800

600

c m -1 )

Fig.2. IR spectra of blown films (4-15~m) in the system AgC1-Ag20-B203. The composition for each spectrum is shown in the inset figure of composition triangle.

50AgBr

Agl

25Ag20" 25 BzO3

blown f i l m

20 4

80 6o

~ AgzO AgBF

20

40 60 370 mol %

\ 1010

Z B03 < , KBr p e l l e t

8203 AgCI

/

BO 4

Bo313 72-k Ag20 ;tO 4Oo, ./60 370 B,03Ag~K)20

400,./6.0

A%O

350 BzO3 1400 '

Fig.l. Glass-forming regions and iso-Tg curves in the systems AgX-Ag20-Bz03 (AgX =AgI, AgBr, AgCI). The numerals in the composition triangles are Tg in °C.

'

~=o 1:;o 0

'

WAVENUMBER

1; 00

'

800

( c m -1 )

Fig.3. Comparison of IR spectra between blown film and KBr pellet.

72 Minami et al. I Structure and ionic conductivity o f glasses

shown in the figure. The composition for each spectrum is given in the inset figure of composition triangle.

and AgI-Ag20-P205

Comparison of spectra between films and KBr pellets

It has been reported that ion exchange easily takes place between Ag + ions in superionic conducting glasses and K + ions in KBr powder when KBr pellet techniques are used for measurements of IR spectra; the exchange caused the peak shift of IR absorption and the peak shift revealed the presence of partial covalency between Ag + ions and non-bridging oxygens in glasses of the systems AgI-AgzO-MoO3 [ii]

4"01

<

:

I

/

The absorption bands at 880 and 1325 cm -I in Fig.3 are new bands which appeared in the KBr pellets; those must be originated by crystallization accompanying the ion exchange. Such a partial crystallization took place in almost all the superionic conducting glasses ion-exchanged with K + ions; among them AgCI-Ag20-B203 glasses were most resistant against the crystallization.

AgC[ CONTENT AgCl-Ag20- 8203 50 system ~/ 40

Agl-Ag20-8203 system Agl CONTENT

2oAso ,o/~o

60

.//

Ag20/8203 mo,o rotio 3

3.0 ,o

,

/

~,

o

I

~

1/2

1/2

40

I

Fig.4. Relative intensity of IR absorptions characteristic of B04 and BO3 groups. The intensity is plotted against AgzO content for glasses containing constant AgX content. left: A g X = AgI, right: A g X = AgCI.

,

~,

~

,

~

,

I 0

Ag! CONTENT ( tool % )

I

20

I

j

0

60

~0

80 A~0~h03

Ag2° 20 40 so 80 SZO3

2~ ' 2o r~ Ag20 CONTENT( tool % )

2

2

//:51

< < o

.~to/O~O..I

/o

o

2 20 40 6080 ~ 2 u 3 /

~ 2.0

=/,:,,o ,';, zo 40 so Bo 00~' I 2~) I 40 I 6C) Ag20 CONTENT ( mo[ %)

Ag20/8203 AgCI- Ag2Osystem8203 .~/rnnl~=~atio

AgI-Ag20- B203 system 4.0

/=o

I/o/ i °I) /JZ-

[16].

In the present glasses the similar ion exchange and peak shift of IR absorption were observed [7, 9]. An example is shown in Fig.3; a glass was selected from the AgBr-Ag20-B203 system. Characteristic bands of BO 3 groups (1310-1255 cm -I) are shifted toward higher wavenumbers (1425-1360 cm -I) by about i00 cm -I, while those of BO4 groups remain unchanged (1010-945 cm-Z). These results must be caused by the ion exchange between Ag + ions in glass and K + ions in KBr powder in the pellet-making process. Accompanying the ion exchange the interaction between non-bridging oxygens and counter cations becomes weaker and hence the B-O bond strength becomes stronger in turn. In other words the strong partial covalency is present between non-bridging oxygens and Ag + ions in the original glass. Non-bridging oxygens are thus shown to be present in BO3 groups only, since the peak shift of the IR absorption was observed only in the bands characteristic of BO 3 groups.

The spectrum (e) of the composition Ag;O" 3B203 is very similar to the spectra already reported for binary AgzO-B203 and RzO-B203 glasses (R=alkali) ; the absorption bands at 1325-1240 cm -i, 1070-890 cm -z and 675-670 cm -~ have been assigned to the v3 mode in BOs groups, the v3 mode in BO~ g r o u p s and the B-O-B bending mode, respectively [14, 15]. The addition of AgCI affects very slightly the wavenumbers of absorption maxima. The glasses with the Ag~O/B20~ mole ratio smaller than those shown in the figure gave essentially the same IR spectra [ 8 ] . From these results we can conclude that the glasses in the systems AgX-AgzO-BzO3 are composed of BO3, BO~ and B-O-B groups, regardless of their chemical composition. 3.2.2.

579

I

40

I

ZO I

60

I

AgCI CONTENT ( tool % )

Fig.5. Relative intensity of IR absorptions characteristic of BO~ and BO3 groups. The intensity is plotted against AgX content for glasses with constant Ag20/B203 mole ratio. left: A g X = AgI, right: A g X = AgCI.

T. Minarni et al. / Structure and ionic conductivity o f glasses

580

Table I. Electrolytic properties of some glasses in the syst~ss AgX-Ag20-B203 (AgX=AgI, AgBr, AgCI). Glass composition (mol %)

Ototal at 25°C (~-rcm-I)

60AgI-30AgzO.10B2Os 40AgI-30AgzO'30Bz03 50AgBr-25AgzO-25BzOs 40AgCI'30AgzO-30BzO3

3.2.3. Relative absorption BO4 and BO s bands

8.5x 2.6x 2.7x 6.3x

l0 -3 l0 -s l0 -3 l0 -4

intensity of

Wavenumbers of IR absorptions characteristic of BO~ and BOs groups were not influenced by the chemical composition of glasses, as shown in Fig.2. However, the relative intensities of BOx and BO3 bands varied with the composition. In Fig.4 the relative intensities are plotted against AgzO content; the results for the systems AgI-AgzO-BzO3 (left figure) and AgCl-AgzO-BzO3 (right figure) are shown as examples for the composition series of constant AgX content. The relative intensity increases linearly with increasing AgzO content in any case in both systems and the straight lines pass through the origin when extrapolated to 0%AgzO. These results indicate that the addition of AgzO is directly related to the formation of BO~ groups. In Fig.5 the relative intensities of BO4 and BO3 bands are plotted against AgX content; the left figure is for AgI-AgzOBzO3 glasses and the right for AgCI-AgzOB203 glasses. In these figures the mole ratio AgzO/BzOs is used as parameters and the composition of the plots is given in the inset figure of composition triangle. The intensity increases linearly with increasing AgX content. Two different tendencies are seen; the slope is gentle for glasses with the mole ratio equal to or less than unity, but it becomes very steep for those with the ratio larger than unity. In the composition region with a gentle slope we could neglect the participation of AgX in the formation of B04 groups, but in the region with the steep slope (glasses with the Ag20/BzO3 ratio larger than unity) we have to consider the role of AgX playing in the formation of BO~ groups. There are two possibilities;one is that AgX added indirectly helps the formation of BOx groups and the other is that AgX added is directly associated with the formation of tetrahedral units containing halide ions in the units, for example, like BOsX, in which X links directly to B.

Transport number of A~ + ion Tubandt method EMF method

0e at 25°C (~-Icm-I) 7.8 x I0 -9

1.017 ± 0.045 J 0.974 ± 0.037

--

7 . 2 x i0 -8 2.4 x i 0 - 9

0.9927 0.9936 --

--

--

Since the slopes are very steep, the latter case is more probable: AgX takes part in the formation of units like BOsX in glasses with the AgzO/BzO3 ratio larger than unity, although new bands attributable to the formation of B-X bonds were not clearly observed, as shown in Fig.2. The absorption bands due to B-X bonds are probably hidden in the broad bands assigned to BO, groups. 3.3. Conductivities 3.3.1.

Electrolytic

properties

Electrolytic properties such as electronic conductivities and transport numbers of Ag + ions were measured for some glasses. Table I lists the properties together with the total conductivity at 25°C. The electronic conductivities by electrons, ~e, are smaller by 5 to 6 orders of magnitude than the total conductivities and the transport numbers of Ag + ions, tAg+ , are practically unity. T h e s e

Agl 2~ 6~5 '

8~60

\11~2 "~'~ o..k5.1o-3

s0/c- 2.10 "4"~ ":6".'~'~5'10"s / \

Ho-' 7 2 ~ - ~ 'Io-6

tool%

AgBr

/ ~'1°'7~"i'~,2.1o -3°-',

Ag~O 20

m0[%

80

AgCt

6o/- .p o-.~-\Ho-3

80 Bz03A~0 20

rnol%

,

80 B203

Fig.6.Iso-conductivity curves of glasses in the systems AgX-AgzO-B203 (AgX= AgI, AgBr, AgCI). The numerals in the composition triangles are the conductivity at 25°C in ~-icm-1

T. Minami et al. / Structure and ionic conductivity o f glasses

g l a s s e s are thus c o n s i d e r e d solid e l e c t r o l y t e s . 3.3.2.

Composition

581

to be good -I

~x

dependence

z

F i g u r e 6 shows the i s o - c o n d u c t i v i t y curves in each s y s t e m A g X - A g 2 0 - B 2 0 3 (AgX= AgI, AgBr, AgCI). The n u m e r a l s shown in the c o m p o s i t i o n t r i a n g l e s are the c o n d u c t i v i t y at 25°C, 0 2 3 , in ~-Zcm-l.

60

0

(121

-2 AgzO

8

\/ 1 \/ 40 60 ~-"{/0 \ a ' z ~

0

20

-3

The O2s values, r a n g i n g from i0 -2 to l0 -7 O-lcm-1, e x h i b i t v e r y s i m i l a r c o m p o s i t i o n d e p e n d e n c e s in the three systems; o2s i n c r e a s e s w i t h i n c r e a s i n g A g X content, b u t does not a l w a y s i n c r e a s e w i t h inc r e a s i n g A g 2 0 content. In the c o m p o s i tion r a n g e w i t h m o r e than 3 0 m o i % AgX, o25 d e c r e a s e s at a g i v e n c o n t e n t of A g X in spite of the i n c r e a s e in the A g 2 0 content. T h e s e r e s u l t s s u g g e s t that all of the Ag + ions in g l a s s d o n o t c o n t r i b u t e to the conduction. F u r t h e r d i s c u s s i o n w i l l be g i v e n in s e c t i o n 3.3.3. In Fig.7 ozs is c o m p a r e d among the g l a s s es c o n t a i n i n g d i f f e r e n t types of AgX. The n u m b e r s w i t h p a r e n t h e s i s in the figure i n d i c a t e the g l a s s c o m p o s i t i o n shown in the inset f i g u r e of c o m p o s i t i o n triangle, and the plots c o n n e c t e d by lines r e p r e s e n t oz5 v a l u e s of g l a s s e s c o n t a i n ing the same a m o u n t s of AgX, A g z O and Bz03. This sort of c o m p a r i s o n was p o s s i ble since the g l a s s - f o r m i n g r e g i o n s of the three s y s t e m s w e r e v e r y similar, as shown in Fig.l.

80

( 6 ) m--'-'---

I 80":

~ -

-

(3)v/

/ o ____-.--~O ~

(11)0~ --'

I

I

AgC[

I

AgBr

AgI

Fig.7. C o m p a r i s o n of c o n d u c t i v i t y at 25 ° C for g l a s s e s c o n t a i n i n g t h e same a m o u n t s of AgX, Ag20 a n d B203. The n u m e r a l s in p a r e n t h e s i s are c o m p o s i t i o n s shown in the inset f i g u r e o f c o m p o s i t i o n

triangle. W e can see that 525 does not d i f f e r

so J

I !%

10-~

~

/

zy~/~

//N•

~ 1()4 u

3

/

h

/

[

v 1 05

Z~

eP

o

Ag20/B203

AgX

/ / /

o

A gBr

AgCI 10-7

/1/3 I (~7

1"1022

z

20 40 6o 8o

o3

I

I

I

1.5

2

25

total A g * i o n s / cm 3 i n g l a s s

Fig.8. Relation between the conductivity a t 25°C and t h e t o t a l concentration of Ag + i o n s in the A g I - A g z O - B 2 0 3 glasses.

I

1.5"1021

I

I

I

I

I

I

I

I

I

2 3 4 5 6 7 8 91"1022 15. Ag* ions / cm 3 f r o m AgX in g l a s s

Fig.9. R e l a t i o n b e t w e e n the c o n d u c t i v i t y at 25°C and the p a r t i a l c o n c e n t r a t i o n of Ag + ions b r o u g h t to the A g X - A g 2 0 - B z O 3 g l a s s e s from the A g X c o m p o n e n t s (AgX = AgI, AgBr, AgCI).

582

T. Minami et aL / Structure and ionic conductivity o f glasses

m u c h among g l a s s e s c o n t a i n i n g d i f f e r e n t AgX; 025 i n c r e a s e s at m o s t by 5 times as AgX v a r i e s from A g C I to A g B r and AgI. Such a small d i f f e r e n c e is a striking c o n t r a s t to the case of A g X - A g z O - P 2 O s g l a s s e s [4, 17, 18]. In the A g X - A g z O P205 g l a s s e s 025 c h a n g e d b y s e v e r a l o r d e r s of m a g n i t u d e w h e n AgX was replaced, and only the Ag + ions i n t e r a c t i n g w i t h Xions w e r e p o s t u l a t e d to take p a r t in the ionic c o n d u c t i o n [4]. In the p r e s e n t glasses, however, we have to take Ag + ions i n t e r a c t i n g w i t h a n i o n s other than X- a n i o n s into c o n s i d e r a t i o n as the cond u c t i v e Ag + ions, b e c a u s e the r e p l a c e m e n t of X- anions i n f l u e n c e d the c o n d u c t i v i t y v e r y slightly. 3.3.3.

01 \B I

A~

I

• t

a

."O'-c• ,, 0 i ,

nv /

",

~,~

I

,ft-~.

"--0--Y/~Ah

~ "B

~

T

Ag ; , /

Aa #~

, : ~-

~,~ ..- 0-'.

C o n d u c t i v i t y vs. Ag + ion c o n c e n tration

F i g u r e 8 shows the r e l a t i o n b e t w e e n oz~ and the Ag + ion c o n c e n t r a t i o n in the g l a s s e s of the s y s t e m A g I - A g 2 0 - B 2 0 3 as an example; in the figure 025 is p l o t t e d a g a i n s t the total c o n c e n t r a t i o n of Ag + ions. L o g a r i t h m i c v a l u e s of o25 v a r y l i n e a r l y but s e p a r a t e l y w i t h the c h a n g e in the total c o n c e n t r a t i o n a c c o r d i n g to the m o l e r a t i o A g 2 0 / B z O 3 . The 025 v a l u e s show not o n l y i n c r e a s i n g but also dec r e a s i n g v a r i a t i o n s w i t h an i n c r e a s e in the total c o n c e n t r a t i o n of Ag + ions. In the g l a s s e s of the other two systems A g B r - A g 2 0 - B 2 0 3 and A g C I - A g z O - B 2 0 3 v e r y similar v a r i a t i o n s w e r e observed. In F i g . 9 025 is ~ l o t t e d a g a i n s t the conc e n t r a t i o n of Ag TM ions b r o u g h t to the A g X - A g 2 0 - B 2 O s g l a s s e s from the A g X comp o n e n t s (AgX=AgI, AgBr, AgCI). Logarithm i c v a l u e s of 025 i n c r e a s e l i n e a r l y w i t h i n c r e a s i n g Ag + c o n c e n t r a t i o n and all the plots in each s y s t e m lie on one s t r a i g h t line, in c o n t r a s t to the case of Fig.8. F r o m these r e s u l t s we can r e a s o n a b l y conc l u d e that a part of Ag + ions in g l a s s c o n t r i b u t e to the ionic conduction, but not all the Ag + ions. It is a g a i n w o r t h noting that the d i f f e r ence in the type of A g X a f f e c t s v e r y s l i g h t l y the c o n d u c t i v i t y . 3.3.4.

XO

G l a s s s t r u c t u r e and c o n d u c t i o n process

IR s p e c t r a r e v e a l e d that the g l a s s e s in the p r e s e n t systems are c o m p o s e d of BO3, BO~, B O 3 X and B - O - B groups, as stated in s e c t i o n 3.2; n o n - b r i d g i n g o x y g e n s are p r e s e n t in BO3 g r o u p s only and bind Ag + ions w i t h strong p a r t i a l covalency. A p a r t of Ag + ions in glass c o n t r i b u t e to the c o n d u c t i o n and the d i f f e r e n c e in Xions s l i g h t l y c h a n g e d the c o n d u c t i v i t y .

Fig.10. S t r u c t u r e m o d e l of A g X - A g z O - B 2 0 3 g l a s s e s e x p l a i n i n g the Ag + ion transport. X = I, Br, CI.

A s t r u c t u r e m o d e l c o m p a t i b l e w i t h the d i s c u s s i o n a b o v e is p r o p o s e d in Fig.10. T h r e e types of Ag + ions are i l l u s t r a t e d in the figure; bared, c i r c l e d and d o u b l e c i r c l e d ones. B a r e d ones are bound w i t h n o n - b r i d g i n g oxygens w i t h strong p a r t i a l covalency. C i r c l e d ones m a i n l y i n t e r a c t w i t h X- ions. D o u b l e - c i r c l e d ones interact w i t h BO[ or BO3X- groups. T h e fact that not all the Ag + ions c o n t r i b u t e to the c o n d u c t i o n suggests that the Ag + ions b o u n d w i t h n o n - b r i d g i n g o x y g e n s take part v e r y s l i g h t l y in the ionic conduction, similar to o t h e r s u p e r i o n i c c o n d u c t i n g g l a s s e s in the systems A g X - A g z O - P 2 O s [4] and A g I - A g e O - M o O 3 [19]. The BO[ or B O 3 X - g r o u p s are singly c h a r g e d anions w i t h large ionic radii, the p r e s e n c e of such anions b e i n g favorable for ionic c o n d u c t i o n [4]. The d o u b l e - c i r c l e d Ag + ions can thus c o n t r i b ute to the c o n d u c t i o n as w e l l as the c i r c l e d ones, and r e s u l t in the small d i f f e r e n c e in c o n d u c t i v i t y of g l a s s e s c o n t a i n i n g d i f f e r e n t X- ions. T h e presence of the d o u b l e - c i r c l e d type of Ag + ions is a s t r u c t u r a l f e a t u r e in B203c o n t a i n i n g g l a s s e s and m u s t c a u s e the c o n t r a s t that the r e p l a c e m e n t of h a l i d e ions c h a n g e d the c o n d u c t i v i t y s l i g h t l y in the B z O 3 - c o n t a i n i n g g l a s s e s w h e r e a s c h a n g e d it c o n s i d e r a b l y in the P20sc o n t a i n i n g glasses.

72 Minami et aL / Structure and ionic conductivity o f glasses

4. SUMMARY Glass-forming regions, glass transition temperatures, IR spectra, conductivities and transport numbers of Ag + ions and electrons were determined for the glasses in the systems AgX-Ag20-B20~ ( A g X = A g I , AgBr, AgCI).

[3]

The glass-forming regions extended to the compositions with the Ag20/B203 mole ratio equal to 3 in each system. IR spectra showed that BO3, BO4 and B-O-B groups are contained in any glass and in addition the groups like BOsX, where X links directly to B, are formed in glasses with the Ag20/B203 ratio larger than unity.

[6]

[4] [5]

[7]

[8]

[9] Ionic conductivities, ranging from 10 -2 to 10 -7 ~-Icm-I at 25°C, do not differ so much among glasses in the three systems containing the same amounts of AgX, AgzO and B203. Relation between the conductivity and the concentration of Ag + ions in glass revealed that not all of the Ag + ions but a part of them contribute to the ionic conduction.

[i0]

[ii]

[12] [13]

A structure model explaining the Ag + ion transport is proposed. It is worth noting that these glasses are i00 % Ag + ion conductors exhibiting very high conductivities and high glass transition temperatures. Acknowledgments This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan, and by the Asahi Glass Foundation for Contribution to Industrial Technology.

[14]

[15]

[16] [17]

[18] REFERENCES [i] Kunze, D., in van Gool, W. (ed.), Fast Ion Transport, p.405 (NorthHolland, Amsterdam, 1973). [2] Minami, T., Imazawa, K. and Tanaka,

[19]

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M., J. Non-Cryst. Solids 42 (1980) 469. Minami, T., J. Non-Cryst. Solids in press. Minami, T. and Tanaka, M., Rev. Chim. Min~r. 16 (1979) 283. Chiodelli, G., Magistris, A. and Schiraldi, A., Electrochim. Acta 23 (1978) 585. Magistris, A., Chiodelli, G. and Schiraldi, A., Electrochim. Acta 24 (1979) 203. Minami, T., Ikeda, Y. and Tanaka, M., J. Chem. Soc. Japan, Chem. Ind. Chem. (1981) 1617 (in Japanese). Chiodelli, G., Magistris, A., Villa, M. and Bjorkstam, J. L., J. NonCryst. Solids 51 (1982) 143. Minami, T., Ikeda, Y. and Tanaka, M., J. Non-Cryst. Solids 52 (1982) 159. Minami, T., Takuma, Y. and Tanaka, M., J. Electrochem. Soc. 124 (1977) 1659. Minami, T., Katsuda, T. and Tanaka, M., J. Non-Cryst. Solids 29 (1978) 389. Minami, T. and Tanaka, M., J. Solid State Chem. 32 (1980) 51. Minami, T., Katsuda, T. and Tanaka, M., J. Electrochem. Soc. 127 (1980) 1308. Adams, R. V. and Douglas, R. W., Proc. 5th Inter. Congress on Glass (Verlag der Deutschen Glastechnischen Gesellschaft, Frankfurt, Germany, 1959) p.VII/12. Wang, J. and Angell, C. A., Glass-Structure by Spectroscopy, Sect.7.5 (Marcel Dekker, New York, 1976). Minami, T., Katsuda, T. and Tanaka, M., J. Phys. Chem. 83 (1979) 1306. Reggiani, J. C., Malugani, J. P. and Bernard, J., J. Chim. Phys. 75 (1978) 849. Malugani, J. P., Wasniewski, A., Dereau, M., Robert, G. and Rikabi, A. A., Mat. Res. Bull. 13 (1978) 427. Minami, T. and Tanaka, M., J. NonCryst. Solids 38/39 (1980) 289.