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INTERNAL FRICTION IN
VANADIUM-PHOSPHATE GLASSES
D. Samatowicz, D. Bednarczyk
To cite this version:
D. Samatowicz, D. Bednarczyk. INTERNAL FRICTION IN VANADIUM-PHOSPHATE GLASSES.
Journal de Physique Colloques, 1983, 44 (C9), pp.C9-171-C9-176. �10.1051/jphyscol:1983921�. �jpa-
00223367�
INTERNAL FRICTION
IN
VANADIUM-PHOSPHATE GLASSESD. Samatowicz and D. Bednarczyk
I n s t i t u t e o f Physics, TeehnicaZ U n i v e r s i t y of GdaGsk, 80-952 Gdarisk, Poland
Re'suad. Les mesures du frottement interieur ont dtb fait dans les verres vanadeux-phosphates pures : xV2o5. 11-x/P205, et additionnds de MgO et CaO
selon deux series : xMgO./0,5-x/~~0~.0,5P~O et X C ~ O . / O , ~ - X / V ~ O ~ . O , ~ P ~ O ~ : 5
/x en mole %/. Nous avons utilis6 un pendule de torsion selon une frdquence de vibration comprise entre 0,5 et 3,5 Hz. La temperature a varis entre 120 K et 650 K. Pour tous les verres nous avons observ6 un maximum du frottement intgrieur li6 3 la relaxation de l'e'lectron entre les ions
v4+
etv5+.
i , r j s t r o c ' ;
-
iii:urri;il < r i ~ ; t l o r i i i 1 C i i O U i ' O T ; i b i 1 ~ 6 i..cre ~ilotic: f o r p u r e va,.,.lc;: ,(:.-..,..
.! i o s p h n t e g l a s s e s xV205./1-::/P205 a n d f o r v a n a d i u n -i . h o s ; ~ h a ? e g l a s s e s d a - , p a d &i:h Pi50 a n d C a 0 , i n 2 s e r i e s :
;:!@./G, 5-x/V,.G 0 , 5 P i: a n d ;:CaO./O, 5 - x / V 05. 0. 5P20
L 5 . 2 5 2 5
1;:
---
, i n moI':j/.; n c m e a s u r e n c r i t s v , e r e p e r f o r m e d r , i t h t h o t o r s i o n p e n d u l u m i n t h e f r e q u e n c y r a n g e 0 . 5
+-
35 llz a n d a t t e m p e r a t u r e s bet1..- ..t.sn 120 I< 2 n d G 5 0 I<.F o r a l l v a n a d i u m
-
p h o s p h a t e g l a s s e s i n t e r n a l f r i c t i o n c u r v e I;,-I ( f ) r e v e a l s t h e l o ' i r j - t e m p e r a t u r e maximumc o n n e c z e d n i t h t h e e l e c t r o n r e l a x a t i o n b e t r - i e s n
v 4 +
a n dv*'
1NTROUUCTI ON
T h e v a n a d i u m
-
p h o s p h a t e g l a s s e s b e l o n g ~ o t h e g r o u p o f s e m i c o n d u c t i n g o x i d e g l a s s e s . L o s t o f i n f o r m a t i o n s a b o u t t h e s e g l a s s e s a r e g a t h e r e d f r o m e l e c t r i c a l c o n d u c t i v i t y s t u d i e s . T h e s e glasses a r c t h e m a t e r i a l s w i t h c l e c r r o n i c c o n d u c t i v i t y a n d r h c p r o c e s s o f c o n d u c t i v i t y i s p o s s i b l e w h e n t h e v a n a d i u m i o n s i n d i f f e r e n t v a l c n c y s t a t e v4' a n dv5+
s i m u l t a n e o u s l y e x i s t . C h a r g e t r a o s p o r z t a k e s p l a c e b y o l o c r r o n t r a n s f e r b e t w e e n t h e s e i o n s /i. e. " h o p p i n g"/.
Tilo n i e c h a n i c a l l a s s o s o f t h e s e q l a s s e s v i e r e s r u d i e d o n l y i n o n e p a p e r
L2.l . T h e a r t i c l e p r e s e n t e d t h e r e s u l t s o f i n t e r n a l f r i c t i o n m e a s u r e m e n t s f o r t h e g l a s s e s c o n t a i n i n g m o r e t h a n 50 nolk, o f V205, p e r f o r m e d i n t h e !;Hz r a n g e o f F r e q u e n c y . T h e m a x i n u n o f i n t e r n a l r r i c t i o n p;as f o u n d a t t h e t e m p e r a t u r e n e a r 200 K. E l e c t r i c a l c o n d u c t i v i t y o f t h e s e g l a s s e s via$ a l s o m e a s u r e d a n d t h e c a l c u l a t e d
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983921
JOURNAL DE PHYSIQUE
v a l u e s o f a c t i v a t i o n e n e r g y o f t h i s p r o c e s s were t n o t i m e s h i g h e r t h a n f o r m e c h a n i c a l l o s a e s . The d i s c u s s i o n d i d n o t g i v e t h e
successful e x p l a n a t i o n o f t h a t d i s c r e p a n c y t h o u g h i t s u g ~ e s t e d t h e h o p p i n g mechanism f o r m e c h a n i c a l l o s s e s as v ' e l l as f o r c o n d u c t i v i t s / process.
I n t h e p r e s e n t paper t h e a u t h o r s o f f e r t h e r a s u l t s o f i n t e r n a l f r i c t i o n measurements f o r tv~o-component vanadium-phosphate $ l a s s e s : xV205/1-x/P205 /x=O.4; 0.3; 0.6; 0.7; = o l e f r a c t i o n / and f o r tvio s e r i e s o f vanadium-phosphate g l a s s e s doped ~ t i t h t h e a l k a l i n e e a r t h m e t a l o x i d e s MgO and CaO: x MgG./O. 5-x/V2o5.0. 5% and
xCa0./0. 5-x/V2G5.0. 5P205 /x=3.1; 0.2; 0.3; 0.4; 0.5; m o l e f r a c t i o n / . The measurements :%ere p e r f o r m e d i n t h e f r e q u e n c y r a n g e 1 s 35 1-12 and a t t e m p e r a t u r e s f r o m 1 2 0 t o 5% X ,
F o r t h e g l a s s m e l t i n g t h e V205, diammoriium p h o s p h a t e /NH4/2HP04, K g 0 and CaO o x i d e s w e r e used. D u r i n g h e a t i n g diamrnonium p h o s p h a t e decomposed i n t o P205, NH3 and H20. U u r i n g s u c c c s i v e h e a t i n g NH3 and H2C v o l a t i l i z e d . The components H e r e p u t i n t o t h e p o r c e l a i n c r u c i b l e s and w r e h e a t e d i n s i l i t e f u r n a n c e t o t h e t e m p e r a t u r e 3 . 3 0 0 ~ ~ . k t t h i s t e m p e r a t u r e t h e components Mere m a i n t a i n e d d u r i n g 1 h o u r . The samples i n r h o f o r m o f t h i n r o d s /3+7 cm i n l e n g t h and 1+2.5 mm d i a m e t r / were drawn f r o m t h e m e l t . T h e n t h e samples were cemented i n b r a z e n h o l d a r s and mounted i n t h e m e a s u r i n g system.
B e f o r e t h e measurements t h e samples k%ere p r e h e a t e d f o r e l i m i n a t i o n t h e s t r a s s e s i n c o n t a c t s between t h e g l a s s and h o l d e r .
The i n t e r n a l f r i c t i o n mcasurements n e r e p e r f orrned i x i t h t h e Z o r s i o n pendulum t e c h n i q u e u s i n g t h e s i m p l e pendulum o f Kt3 t y p e as $ % e l l as t h e i n v e r t e d p ~ n d u l u m . L o g a r i t h m i c decrement o f f r e e v i b r a t i o n s damping
6 /u-'
=d / n /
%as d e t e r m i n e d . S i m u l t a n e o u s l yt h e v i b r a t i o n f r e q u e n c y F was r e c o r d e d . The s q u a r e o f f r e q u e n c y i s p r o p o r t i o n a l t o t h e s h e a r modulus / f 2- G/. The rneasured g l a s s e s n e r e c h e m i c a l l y s t a b l e and n o n h y y r o s c o p i c f o r a l l c h e m i c a l c o m p o s i t i o n s and i n a l l a p p l i e d t e m p e r a t u r e range.
F i g . 1 s h o w soma e x e m p l a r y c u r v e s Q-'/T/ f o r xV205./1-x/P205
g l a s s e s t h e c h a r a c t e r i s t i c f e a t u r e o f a l l t e s t e d g l a s s e s From t h i s s e t i s t h e l o w t e m p e r a t u r e maximum a t t h e t e m p e r a t u r e below 200K.
F o r d e f i n e d c o m p o s i t i o n o f t h e g l a s s i r o m t h i s s e r i e s , maximum
modulus G /T/. These two f a c t s t e s t i f y t o r e l a x a t i o n c h a r a c t e r o f t h e process r e s p o n s i b l e f o r t h e f o r m a t i o n o f t h i s maximum.
Comparing t h e i n t e r n a l f r z c t i o n c u r v e s Q-/T/ f o r d i f f e r e n t samples from t h i s s e r i e s i t can be s t a t e d t h a t low-temperature maximum s h i f t s t o l o w e r t e m p e r a t u r e s l hen t h e V205 c o n t e n t i n c r e a s e s ; a t t h e same t i m e t h e a c t i v a t i o n energy decreases and t h e r e l a x a t i o n t i m e i n c r e a s e s . I n T a b l e I t h e r e a r e l i s t e d t h e p r e c i s e v a l u e s o f maximum t e m p e r a t u r e Tmlz l-l a t 1 Hz, r e l a x a t i o n t i m e and a c t i v a t i o n e n e r g i e s f o r mechanical. l o s s e s as w e l l as f o r e l e c t r i c c o n d u c t i v i t y and d i e l e c t r i c l o s s e s [ 2 ] ~ 1 1 1 t h e s e t h r e e v a l u e s o f a c t i v a t i o n energy a r e c l o s e d t o each o t h e r and t h e d i s c r e p a n c i e s a r e i n t h e l i m i t s o f e r r o r . T h i s f a c t suggests t h e same mechanism f o r a l l t h r e e processes. The h i g h v a l u e s o f
% / l o - l o
+1oW7s/ i n d i c a t e t h a t t h e r e l a t e d process can n o t be connected w i t h t h e i o n m i g r a t i o n , Because t h e o p i n i o n o f t h e hopping c h a r a c t e r o f c o n d u c t i v i t y and e l e c t r i c a l l o s s e s i s now r a t h e r w e l l known, vie accept t h a t t h e mechanical l o s s e s a r e a l s o connected w i t h t h i s process. The i n c r e a s e o f ?& w i t h t h ei n c r e a s i n g c o n t e n t o f vanadium i n d i c a t e s t h e i n c r e a s e o f a c t i v a t i o n e n t r o p y w h i c h i s caused by s t r o n g e r i n t e r a c t i o n between i o n i c
environment and
v4+
i o n . A t h i g h c o n t e n t s o f vanadium t h o i n f l u e n c e o f p o s i t i v e f i e Z d o f a d j a c e n t vanadium i o n s on bond energy between e l e c t r o n andv4+
i o n i n c r e a s e s . Consequently t h e a c t i v a t i o n energy i n t h e hoppning process decreases.The o p i n i o n o f a h o p p i n g c h a r a c t e r o f t h e p r o c e s s r e s p o n s i b l e f o r t h e l o w t e m p e r a t u r e maximum was c o n f i r m e d by f u r t h e r measurements o f i n t e r n a l f r i c t i o n i n two s e t s o f g l a s s e s w i t h m o d i f i e r o x i d e s MgO and CaO
-
F i g . 2 and 3. I n b o t h cases, when t h e c o n t e n t o f added o x i d e i n c r e a s e s / t h e amount o f V205 decreases/t h e low-temperature maximum decreases and s h r f t s t o h i g h e r
temperatures, so t h e a c t i v a t i o n energy o f t h e p r o c e s s r e s p o n s i b l e f o r t h i s maximum i n c r e a s e s . T h i s maximum i s v e r y s m a l l i n samples c o n t a i n i n g 0.1 V205 /O. 1V205.0.4Mg0.0. 5P2.05 and 0.1 V205.0.4Ca0.
.0.5P205/ and d i s a p p e a r s i n g l a s s e s w i t h o u t V205 oxide. Then t h e presence o f m o d i f i e r does n o t l e a d t o a new r e l a x a t i o n proces and t h e observed maximum i s connected w i t h t h e presence o f V205 oxide, I n t h e presence o f PIg2+ m o d i f i e r t h e observed l o w - t e m p e r a t u r e maximum has h i g h e r a c t i v a t i o n energy and i s s h i f t e d t o h i g h e r
temperatures more t h a n i n a case o f ca2' m o d i f i e r . The
cations
JOURNAL DE PHYSIQUE
h a v e h i g h e r c a t i o n p o t e n t i a l
Y
t h a n ca2' c a t i o n s/If
My2*=3.08, y C a 2 + = 2.02/ a n d t h e i r s t r o n g e r p o l a r i z a t i o n i n t e r a c t i o ni n t r o d u c e s g r e a t e r d e f o r m a t i o n i n t h e n o a r e s t s u r r o u n d i n g s o f V 4+
a n d
v5*
i o n s . H e n c e , t h e a c t i v a t i o n e n e r g y o f r e l a x a t i o n p r o c e s s i n t h e g l a s s e s v r i t h t",sO i s h i g h e r t h a n i n t h e g l a s s e s w i t h CaO. F o r b o t h s e t s o f g l a s s e s w i t h ClgO a n d CaO o x i d e s t h e r e s u l t s o fe l e c t r i c a l c o n d u c t i v i t y m e a s u r ~ m e n t s a r e .el1 kn0.n
[ZI].
I n t h i s c a s e t h e r e i s a l s o a n e x a c t c o r r e l a t i o n w i t h t h e m e c h a n i c a l l o s s e s m e a s u r e m e n t s . Lihen t h e V 2 0, 2 c o n t e n t d e c r e a s e s c o n d u c t i v i t y v a l u e s d e c r e a s e s a n d t h e a c t i v a t i o n e n e r g y o f t h i s p r o c e s s i n c r c a s e s , T h e v a l u e s o f a c t i v a t i o n e n e r g i e s c a l c u l a t e d from t h e c o n d u c t i v i t y m e a s u r e m e n t s a r e s i m i l a r t o t h e v a l u e s of a c t i v a t i o n e n e r g yc a l c u l a t e d f r o m t h e m a c h a n i c a l l o s s e s n e a s u r e a c ; : t - T n k i e I / t h e v a l u e s o f a c t i v a t i o n e n e r y y f o r c o n d u c t i v i t y a r e s o m e n h a t h i g k e r
t h a n f o r m e c h a n i c a l l o s s e s , i t i s p r o b a b l y c o n n e c t e d w i t h t h e h i g h e r r e m p e r a t u r e r a n g e o f e l e c t r i c m e a s u r e m e n t s / .
T h e r e s u l t s o f i n t e r n a l f r i c t i o n m e a s u r e m e n t s f o r t h r e e s e t s o f v a n a d i u m - p h o s p h a t e g l a s s e s , p r e s e n t e d i n t h i s p a p e r , i n
c o n n e c t i o n w i t h t h e e l e c t r i c a l c o n d u c t i v i t y a n d d i e l e c t r i c l o s s e s m e a s u r e m e n t s c o n f i r m t h e o p i n i o n a b o u t a h o p p i n g c h a r a c t e r o f a r e l a x a t i o n p r o c e s s r e s p o n s i b l e f o r t h e l o w - t e m p e r a t u r e maximum.
T h e s u p l e m e n t a r y m e a s u r e m e n t s o f i n t e r n a l f r i c t i o n f o r t h e g l a s s e s w i t h t h e d e f i n e d c o n c e n t r a t i o n
v4*/v
t o t a l a s ell a s s t r u c t u r a l m e a s u r e m e n t s s h o u l d c o n t r i b u t e t o b e t t e r e x p l a n a t i o n o f t h e m e c h a n i c a l r e l a x a t i o n p r o c e s s e s i n t h e s e g l a s s e s .T h i s * o r [ < v4as s u p p o r t e d by P o l i a h Academy o f S c i e n c e s ~ ~ i r h i n t h e f r a m e MR.I.24.
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1. M.B. F i e l d , J. A p p l . P h y s . , 4 0 , 2 6 2 8 - 2 6 3 2 / 1 9 G 8 /
2, A. M i s z c z y k , D i p l o m a , T e c h n i c a l U n i v e r s i t y , G d a r i s k /1981/
3. S. H e n c l i k , D i p l o m a , T e c h n i c a l U n i v e r s i t y , Gdarisk /1982/
C9-176 JOURNAL DE PHYSIQUE
.,. .
1'1.g.1. I n t e r n a l f r i c t i o n i n v o nt;dic;ir:-phoapha t e g l a s s e s .
T e m p e r a t u r e dependen- c e o f t e r n a l f r i c - t i o n
zLP/r/
i n vana- dium p h o s p h a t e g l a s - s e s w i t h ihgO m o d i f i e r .T e n p e r a t u r e dependen- c e of i t e r n a l f r i c - t i o n Q-?/!P/ i n vana- diuiil-phospha t e g l a s - s e s w i t h C a O m o d i f i e r .
