MÖSSBAUER STUDIES OF JAPANESE ANCIENT POTTERY

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MÖSSBAUER STUDIES OF JAPANESE ANCIENT POTTERY

Y. Maeda, H. Sakai, S. Onoyama, E. Yoshida

To cite this version:

Y. Maeda, H. Sakai, S. Onoyama, E. Yoshida. MÖSSBAUER STUDIES OF JAPANESE ANCIENT POTTERY. Journal de Physique Colloques, 1979, 40 (C2), pp.C2-485-C2-486.

�10.1051/jphyscol:19792169�. �jpa-00218544�

JOURNAL DE PHYSIQUE

Colloque C2, suppldment au n

3, Tome

mars 1979, page

M ~ S S B A U E R S T U D I E S OF JAPANESE A N C I E N T POTTERY

Y. Maeda, H. S a k a i , S. Onoyama and E. Yoshida. X

**

Research Reactor I n s t i t u t e , Kyoto University, Osaka,

* ~ e ~ a r t m e n t o f History, Faculty o f Letters, Kyoto University, Kyoto,

Japan.

* * ~ a r a National Research I n s t i t u t e o f Cultural P r o p e ~ t i e s , Nara,

R6sumb.- La s p e c t r o s c o p i e Mijssbauer a b t 6 u t i l i s 6 e pour c a r a c t b r i s e r , d e s J a p o n a i s e s a n c i e n n e s ( g u e r r e s d e H a j i e t S u e ) ; Les c o n d i t i o n s d e c u i s s o n t e l l e s que l a t e m p b r a t u r e e t l ' a t - mosphere du f o u r o n t Et6 o b t e n u e s p a r comparaison a v e c l e s donnbes f o u r n i e s p a r une e x p s r i e n c e d e s i m u l a t i o n s u r a r g i l e .

A b s t r a c t . - % s s b a u e r s p e c t r o s c o p y h a s b e e n u s e d t o c h a r a c t e r i z e J a p a n e s e a n c i e n t p o t t e r y from H a j i and Sue wares. The f i r i n g c o n d i t i o n s s u c h a s t e m p e r a t u r e and atmosphere were deduced from a model f i r i n g e x p e r i m e n t o n c l a y .

I n o r d e r t o s o l v e t h e m a n u f a c t u r i n g t e c h n i q u e , mainly t h e f i r i n g t e c h n i q u e , f o r J a p a n e s e a n c i e n t p o t t e r y , we have a p p l i e d Msssbauer s p e c t r o s c o p y on i r o n c o n t a i n e d w i t h i n t h e c l a y and p o t s h e r d s . I n J a p a n v a r i o u s k i n d s o f p o t t e r y , s u c h a s Jomon. Ya- y o i , H a j i , Sue and g l a z e d p o t t e r y , were made and u s e d i n t h e d a i l y l i v i n g o r r e l i g i o u s s e r v i c e s . Among them, Jomon and Yayoi w a r e s have been u s e d

a s an i n d i c a t o r f o r t h e c l a s s i f i c a t i o n o f a n c i e n t t i m e s . At t h e Kofun age (A.D.4-7c.) we found two q u i t e d i f f e r e n t k i n d s o f u n g l a z e d p o t t e r y . One i s r e d ware c a l l e d H a j i , which was made w i t h manufac- t u r i n g t e c h n i q u e o r i g i n a t e d w i t h p r e v i o u s J a p a n e s e e a r t h e n w a r e s (Jomon and Yayoi). It was f i r e d i n t h e open a i r , n o t i n k i l n s . The f i r i n g c o n d i t i o n i s supposed t o b e under o x i d i z i n g atmosphere a t t h e t e m p e r a t u r e s r a n g i n g from 500 t o 7 0 0 ' ~ . On t h e con- t r a r y . Sue p o t t e r y i s g r e y w a r e , which i s t h e o r i - g i n o f l a t e r J a p a n e s e p o t t e r y . It is t h e f i r s t pot- t e r y f i r e d i n k i l n s u s i n g Chinese t e c h n i q u e t r a n s - m i t t e d t h r o u g h Korean P e n i n s u l a . S i n c e i t was baked h a r d e r t h a n p r e v i o u s p o t t e r y by u s i n g k i l n s o f a t u n n e l s t r u c t u r e , t h e f i n a l f i r i n g c o n d i t i o n seems t o b e u n d e r r e d u c i n g atmosphere a t h i g h e r tempera- t u r e s . The f i r i n g t e m p e r a t u r e o f 1100-120O0C a r e d6duced s o f a r by many t e c h n i q u e s .

P r i o r t o t h e e x a m i n a t i o n o f p o t s h e r d s o f an- c i e n t w a r e s , t e s t f i r i n g s were c a r r i e d o u t w i t h s e v e r a l k i n d s o f c l a y . The s e l e c t i o n o f c l a y i s a n i m p o r t a n t s t e p i n m a n u f a c t u r i n g p o t t e r y . It i s , however, v e r y d i f f i c u l t t o g e t t h e c l a y which was p r o b a b l y used f o r a n c i e n t p o t t e r y . Then s e v e r a l k i n d s o f c l a y were c o l l e c t e d from a r e a s c l o s e t o Sue k i l n s i t e s (Semboku H i l l s o f s o u t h e r n S a k a i , Osaka) and w e r e compared w i t h t h e c l a y which was

c e r t a i n l y u s e d t o m a n u f a c t u r e Old E c h i z e n ware (A.D. l l-12c.) The i r o n c o n t e n t i s found t o b e a b o u t I % i n t h e s e c l a y s and 1 ~ 2 % i n p o t s h e r d s . W O appa- r e n t l y d i f f e r e n t c l a y s were s e l e c t e d f o r t h e t e s t f i r i n g . One i s v e r y f i n e and homogeneous, and ano- t h e r i s w e a t h e r e d and c r u d e . E c h i z e n c l a y i s a l s o f i n e and homogeneous. The t e s t f i r i n g was performed by u s i n g a n e l e c t r i c a l f u r n a c e a t d i f f e r e n t tempera- t u r e s up t o 1250°C. The o x i d i z i n g atmosphere was a i r , w h i l e t h e r e d u c i n g atmosphere was a r g o n o r vapor- s a t u r a t e d CO2-CO ( 4 % m i x t u r e . The f i r i n g t i m e was 5

h o u r s a t e a c h t e m p e r a t u r e .

The most s t r i k i n g r e s u l t o f t h e t e s t f i r i n g i s t h e f a c t t h a t t h e Msssbauer s p e c t r a o f t h r e e d i f f e - r e n t f i r e d - c l a y shows a same f e a t u r e i n t h e depen- dence on t h e f i r i n g c o n d i t i o n s - T h e r e f o r e , i t may b e p o s s i b l e t o a c e r t a i n d e g r e e t o deduce t h e f i r i n g t e c h n i q u e o f p o t t e r y , even though we have no d e t a i l e d knowledge a b o u t t h e s o u r c e of t h e c l a y used f o r pot- t e r y .

The ~ b ' s s b a u e r s p e c t r a of t h e u n f i r e d c l a y a r e c h a r a c t e r i z e d by t h r e e a p p a r e n t peaks which c a n b e a n a l y z e d i n t o two q u a d r u p o l e d o u b l e t s c o r r e s p o n d i n g t o Fe (11) and Fe (111) i n t h e o c t a h e d r a l s i t e o f c l a y m i n e r a l s . The i n t e n s i t y r a t i o f o r F e ( I 1 ) a n d F e (111) i s 30:70. Any m a g n e t i c h y p e r f i n e p a t t e r n s were n o t o b s e r v e d . With f i r i n g above 4 0 0 ' ~ under t h e o x i - d i z i n g a t m o s p h e r e , t h e f e r r o u s i o n was c o m p l e t e l y o x i d i z e d and o n l y t h e Fe (111) q u a d r u p o l e d o u b l e t was o b s e r v e d . F i r i n g above 1000°C b r i n g s a b o u t a s m a l l amount o f m a g n e t i c p a t t e r n . The i n t e r n a l m a g n e t i c f i e l d i s 450kOe, w h i c h may be a t t r i b u t e d t o (Fel-xAlx) 203. On t h e c o n t r a r y , t h e c l a y f i r e d under r e d u c i n g a t m o s p h e r e e x h i b i t e d o n l y t h e Fe (11) q u a d r u p o l e dou- b l e t . The f i r i n g t e m p e r a t u r e dependences of t h e isomer

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792169

c2-486 JOURNAL

PHYSIQUE shifts and the quadrupole splittings of Echizen

clay are shown in figure

for both oxidizing and reducing conditions.

TEMPERATURE ( * C )

Fig.

Isomer shift (I.S.) and quadrupole split- ting (Q.S.) of ferrous and ferric ions in clay at various temperatures. Gssbauer measurements were carried out at room temperature.

As reported

Janot andDelcroix /I/ and Bouchez

et

such behaviours are well understood with

-

the thermal transformation of clay minerals.

The typical Mzssbauer spectra of potsherds at 77 K are shown in figure 2 for Haji and Sue wares.

The spectrum of red Haji ware is characterized by two iron forms: the octahedral Fe (111) in clay minerals (Q.S.=0.94mm/s, I.S.=O.45mm/s vs. iron metal! and (Fel-xAlx)203 (Hint

525kOe).

L "

. . .

-1 0 0 10

VELOCITY lmm/r)

Fig. 2

Typical ~Essbauer spectra at 77 K for Haji (a) and Sue (b) wares.

Since Haji ware does not show ferrous spectra at all, its firing condition is concluded to be under an oxidizing atmosphere. Nevertheless, it is ambi- guous whether the iron oxide was originally contai- ned as an impurity or was formed directly from clay minerals through the heat treatments. As confirmed in the test firing, such a large amount of magnetic substances cannot be expected in fine clay. Crude clay including one of marine origin might be used for Haji ware.

On the other hand, the typical spectrum of Sue ware is characterized by octahedral Fe

(Q.S.=2.57mm/s, I.S.=1.18m/s) accompanied with a small amount of octahedral Fe (111) (Q.S.= 1.03mm/s, I.S.=0.48mm/s). Usually Sue pottery has a great va- riety in its colour. As the colour becomes red from grey, the content of Fe (111) generally increases.

Contrary to Haji ware, it is very clear that Sue ware was finally fired under a reducing condition.

As Sue ware often has a reddish brown core, it is supposed that the ware was fired under an oxidizing condition and at the final stage of firing was kept under a reducing condition.

By comparing the spectra of potsherds with those of test fired clay, the firing temperature can be deduced. As shown in figure

the quadru- pole splitting and the isomer shift of Fe (11) are very temperature dependent in the range between 700 and 1250°C. However, the change is not monotonic, so that some further treatments are necessary. When potsherds are annealed in the furnace, the MEssbauer spectra begin to change at the temperature supposed to be fired. By giving further heat treatments to potsherds, it is possible to determine the firing temperature with considerable accuracy. With this method, a number of Sue potsherds have been measu- red in the relation of the provenance, the type of kiln and the age. The estimated firing temperature has a distribution ranging from 800 to 1060°c, in- dependently of the provenance and the kiln. This estimation is rather low in comparison with those of other methods such as X-ray diffraction and ther- mal analysis.

This work was supported by a Grant-in-aid of the Minis~ry of Education, Japan. The authors wish to express their hearty thanks to Mr. H.

Nakamura for sample collection and useful discus- sions.

References

/I/ Janot, Ch., Delcroix, P., J. Physique Col1oq.z (1974) C6-557.

/2/ Bouchez, R., Coey, J.

D., Coussement, R., Schmidt, K. P., van Rossum, M., Aprahamian, J., Deshayes, J., J. Physique Colloq. 2 ⁽¹⁹⁷⁴⁾

C6-541.