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Grain orientation and critical current of tape-casted and hot-forged superconducting Bi(Pb)SrCaCuO ceramics
Physica C 185-189 (1991) 2425-2426 North-Holland
GRAIN ORIENTATION AND CRITICAL CURRENT OF TAPE-CASTED AND HOT-FORGED SUPERCONDUCTING Bi(Pb)-Sr-Cs-Cu-O CERAMICS Takahiro SEKI, Koichiro SAKATA a n d Tadashi TAKENAKA F a c u l t y of S c i e n c e and T e c h n o l o g y , Science U n i v e r s i t y of Tokyo, Noda, Chiba-ken, 278 JAPAN A preferred
g r a i n orientation o f h l g h - T c s u p e r c o n d u c t i n g Bi(Pb)-Sr-Ca-Cu-O ceramics with a large a n l s o t r o p i c c r y s t a l s t r u c t u r e c a n be given b y t h e t a p e - c a s t i n g (TC) a n d h o t - f o r g i n g (HF) (TC÷HF) method. The g r a i n in t h e TC÷RF samples were o r i e n t e d p e r p e n d i c u l a r to t h e c-axis, which lies in a f o r g i n g d i r e c t i o n . The g r a i n o r i e n t a t i o n factor, F, was estimated b y t h e X - r a y diffraction p a t t e r n s , for example, F = 0.9. The critical c u r r e n t density, J c [ a b ] (=840A/cm ~) of t h e a b - p l a n e was elevated 14 times as l a r g e a s t h e Jc[OF] of t h e u n o r i e n t e d (OF) samples b y t h e TC÷HF method. 1. INTRODUCTION The d i s a d v a n t a g e of t h e oxide ceramic s u p e r c o n d u c t o r is t h a t a critical c u r r e n t d e n s i t y , Jc, is generally less t h a n t h a t of t h e s i n g l e c r y s t a l or t h e g r a i n - o r i e n t e d thin film. To e n h a n c e the Jc, it is r e q u i r e d t o o r i e n t t h e g r a i n s to p e r p e n d i c u l a r to c-axis. As a g r a i n orientation t e c h n i q u e , we applied t h e h o t - f o r g i n g ( a b b r e v i a t e d to "HF ~) method ~ to t h e B I ( P b ) - S r - C a - C u - O ceramics. However g r a i n o r i e n t a t i o n factor, F, of t h e HF samples was not so h i g h (F -- 0.6 - 0.7) e. Recently, we h a v e tried to combine t h e t a p e - c a s t i n g ( a b b r e - viated to "TC") method ~-a with t h e HF method to the B i ( P b ) - S r - C a - Cu-O ceramics. In this p a p e r , grain o r i e n t a t i o n effects on s u p e r c o n d u c t i n g p r o p e r t i e s of the B i ( P b ) - S r - C a Cu-O ceramics h a v e been i n v e s t i g a t e d using t h e t a p e - c a s t i n g (TC) and h o ~ - f o r g t n g (HF) method. The g r a i n o r i e n t a t i o n e f f e c t s o n t h e s u p e r c o n d u c t i n g p r o p e r t i e s of TC÷HF samples are expected to exhibit e n h a n c e d Jc.
was statically applied aL 800~ along the thickness of t h e sample (the f o r g i n g axis). After c u t t i n g for measurements, samples were annealed at 850"C for I0 - 50 h in air. Evaluation of t h e TC÷HF samples was performed f o r the grain orientation factor, F. u s i n g the Lotgering method. Electrical c h a r a c t e r i s t i c s were measured by a s t a n d a r d f o u r - p r o b e method. 3. RESULTS AND DISCUSSION F i g u r e I shows X - r a y diffraction p a t t e r n s of (a) t h e p e r p e n d i c u l a r and ( b ) the parallel planes Bh~bo..Sr,.9,Ca2 ~Cu3.~O. i (a} TC+H.F
o
.~~, ..
Q
g'~
Press
c:~
~
o !
0
Press
Co) T C + m V (#c)
:
0
2. E X P E R I M E N T A L
The a p p r o p r i a t e a m o u n t s of Bi203, PbO, SrC03, Cat03 and CuO powders were mixed in molecular ratio of Bi~. 8,Pbo. 3,Sr~. 9 ~Ca2. o ~Cu,. o sO. % After calcined at 800"13 f o r 10 h, the mixtures were h e a t t r e a t e d at 85022 f o r 50 h to form t h e h i g h - T o phase of the ~ l - ~ r - t ~ a - ~ u - u system. The ceramlc powders were ball-milled i n t o a fine powder, and then milled t o g e t h e r with o r g a n i c formulations. T h e r e s u l t i n g s l u r r y was t a p e - r a n t u n d e r a doctor blade into 100 u m-thick g r e e n s h e e t on p o l y e t h y lene c a r r i e r s h e e t . Samples were c u t from the green s h e e t a n d a t h e r m o c o m p r e s s i o n bonding was applied to 50 - 10O sheets. The bonded s h e e t s were h e a t - t r e a t e d at 500"(; for 50 h to remove t h e organic formulation. A unlaxial ccmpressional l~ad
.= O) O F LAI,~
~ ~.
. I
19
20
30
40
50
60
29 [degree]
FIGURE 1 X-ray diffraction p a t t e r n s of (a) the pependicular (_L} and (b) the parallel ( / / ) planes, to the forging axis. of the TC*HF, a n d (c) the OF ~]i(Pb)-Sr-CaC u - O ceramh.s.
0921-4534DI/$03.50 O 1991 - Elsevier Science P~ 9lishcrs B.V. AH fighas reserved
/ Tape-casted and hot.forged superconducting Bi (Pb).Sr-Ca-Cu-O ceramics
T Seld et at
2426
to t h e f o r g i n g axis ( c o r r e s p o n d i n g to t h e c - a x i s ) of t h e TC÷HF, a n d (c) t h e o r d i n a r y f i r i n g ( a b b r e v i a t e d to "OF") s m a p l e s without o r i e n t a t i o n . An almost single p h a s e with t h e c-axls o r i e n t a t i o n of h l g h - T c p h a s e In B I - S r - e a - C u - O s y s t e m oc,uld be o b s e r v e d . The g r a i n o r i e n t a t i o n f a c t o r , F, was e s t i m a t e d as F = 0.9 f o r F i g . l (a). F i g u r e 2 shows t h e t e m p e r a t u r e d e p e n d e n c e of t h e r e s i s t i v i t y , o , f o r (a) t h e p e r p e n d i c u l a r p l a n e ( a b - plane} and (b) t h e parallel direction (c-axis), to t h e f o r g i n g axls, of t h e TC÷HF samples. The z e r o r e s i s t a n c e s t a t e ( o =0) was a c h i e v e d a t 104 K. 25
1.0 I Bi,~Pb~aSr,.,,Ca,.o,Cu,.~O,
8
0.8
&
0.6
e
0.4 0.2 0
I
'-°+ °
.~-
t5
I
0
50
100
150
200
250
Temperature [K] FIGURE 2 T e m p e r a t u r e d e p e n d e n c e of the r e s i s t i v i t y , O, f o r (a) t h e p e r p e n d i c u l a r (the a b - p l a n e ) a n d (b) t h e parallel (the c-ax~s), to t h e f o r g i n g axis, of t h e TC+HF. 10~
Bi,+~Pbo_~Sr,.gtCa2.mCu,.~O~
1¢
~
The a n l s o t o r o p y of p a t T c [ o n s e t ] in t h e p e r p e n d i c u l a r a n d the parallel p l a n e s to t h e f o r g i n g axis was a b o u t 45. Critical c u r r e n t d e n s i t y , J c [ a b ] a n d J c [ c ] , of t h e a h - p l a n e and t h e c - a x i s should he c o m p a r e d with Jc[OF] of t h e OF sample. The J c [ a b ] (=840 A/cm 2) a t 77 K u n d e r n o magnetic field f o r t h e TC÷HF samples was e l e v a t e d a b o u t 14 times a s l a r g e a s t h a t Jc[OF| (=60 A/cm ~) of u n o r l e n t e d (OF) sample. This d e m o n s t r a t e s t h a t t h e g r a i n o r i e n t a t i o n b y t h e t a p e - c a s t i n g and h o t - f o r g i n g (TC+HF) is efficacious f o r t h e e n h a n c e m e n t of t h e dc. I n s p i t e of h i g h o r i e n t a t i o n f a c t o r (F = 0.9), h o w e v e r , J c is not so h i g h . This seems to be c a u s e of t h e weak coupling of g r a i n b o u n d a r y . F i g u r e 3 shows t h e m a g n e t i c field d e p e n d e n c e of t h e critical c u r r e n t d e n s i t y , Jc, a t 77 K Por TC.HF a n d OF samples. T h e magnetic field was a p p l i e d on both p e r p e n d i c u l a r to t h e c u r r e n t a n d p e r p e n d i c u l a r or parallel t o t h e c-axis. I t c l e a r l y c o n f i r m s to be e n h a n c e d t h e dc[ab] u n d e r m a g n e t i c field b y t h e g r a i n o r i e n t a t i o n e f f e c t s . 4. CONCLUSIONS T h e g r a i n o r i e n t a t i o n e f f e c t s on t h e s u p e r c o n d u c t i n g p r o p e r t i e s of t h e B i ( P b ) - S r - C a - C u - O c e r a m i c s a r e s t u d i e d u s i n g combination t h e t a p e c a s t i n g (TC) method with t h e h o t - f o r g i n g (HF) method. The g r a i n o r i e n t a t i o n factor, F, of a b o u t 0.8 - 0.9 was estimated f r o m X - r a y d i f f r a c t i o n patterns. A s u p e r c o n d u c t i n g t r a n s i t i o n ( p = 0) a t 104 K was o b s e r v e d for t h e TC+HF samples. We also c o n f i r m e d t h e a n i s o t o r o p y in t h e r e s i s t i v i t y of t h e a b - p l a n e a n d c-axis of TC÷HF samples. T h e c r i t i c a l c u r r e n t d e n s i t y , J c [ a b ] , was e n h a n c e d 14 times a s t h e Jc[OF] of t h e u n o r i e n t e d samples b y t h e g r a i n o r i e n t a t i o n effects. REFERENCES
c-axts B
1. T. T a k e n a k a , ft. Noda, A. Yoneda, K. S a k a t a , J p n . J. Appl. P h y s . 27~ (7), (1988) L1209
i0
2. T. T a k e n a k a , H. Noda a n d K. Sakata, Ceramic
n
l
R
0.2
!
0.4
I
i
~.6
0.8
Magnetic field, B [3"] FIGURE 3 Magnetic field d e p e n d e n c e of the ccit~c.al c u r r e n t d e n s i t y , Jc, of t h e TC+HF and the OF.
3. K. Togano, H. Kumakura, H. Naeda, N. Irisawa, E. Yanag/sa~,a, d. Shimoyama, T. Ner~moto, J p n . J. AppL Phys. 2_8 (1989) L95. 4. E. Yamnag[sawa, T. Nor[moto, D. R. Dietderich, Ho N~!ma~ura, K. Togano, H. Maeda, AppI. P h y s . Lett. 5_4 (25), 1t989} 2602. 5. U. Endo, S+ K¢)'C,+~,;a~ ~. KawaL Jpn. d. Appl. P h y s . 28 (1989} L J"~':~ G,~.
GRAIN ORIENTATION AND CRITICAL CURRENT OF TAPE-CASTED AND HOT-FORGED SUPERCONDUCTING Bi(Pb)-Sr-Cs-Cu-O CERAMICS Takahiro SEKI, Koichiro SAKATA a n d Tadashi TAKENAKA F a c u l t y of S c i e n c e and T e c h n o l o g y , Science U n i v e r s i t y of Tokyo, Noda, Chiba-ken, 278 JAPAN A preferred
g r a i n orientation o f h l g h - T c s u p e r c o n d u c t i n g Bi(Pb)-Sr-Ca-Cu-O ceramics with a large a n l s o t r o p i c c r y s t a l s t r u c t u r e c a n be given b y t h e t a p e - c a s t i n g (TC) a n d h o t - f o r g i n g (HF) (TC÷HF) method. The g r a i n in t h e TC÷RF samples were o r i e n t e d p e r p e n d i c u l a r to t h e c-axis, which lies in a f o r g i n g d i r e c t i o n . The g r a i n o r i e n t a t i o n factor, F, was estimated b y t h e X - r a y diffraction p a t t e r n s , for example, F = 0.9. The critical c u r r e n t density, J c [ a b ] (=840A/cm ~) of t h e a b - p l a n e was elevated 14 times as l a r g e a s t h e Jc[OF] of t h e u n o r i e n t e d (OF) samples b y t h e TC÷HF method. 1. INTRODUCTION The d i s a d v a n t a g e of t h e oxide ceramic s u p e r c o n d u c t o r is t h a t a critical c u r r e n t d e n s i t y , Jc, is generally less t h a n t h a t of t h e s i n g l e c r y s t a l or t h e g r a i n - o r i e n t e d thin film. To e n h a n c e the Jc, it is r e q u i r e d t o o r i e n t t h e g r a i n s to p e r p e n d i c u l a r to c-axis. As a g r a i n orientation t e c h n i q u e , we applied t h e h o t - f o r g i n g ( a b b r e v i a t e d to "HF ~) method ~ to t h e B I ( P b ) - S r - C a - C u - O ceramics. However g r a i n o r i e n t a t i o n factor, F, of t h e HF samples was not so h i g h (F -- 0.6 - 0.7) e. Recently, we h a v e tried to combine t h e t a p e - c a s t i n g ( a b b r e - viated to "TC") method ~-a with t h e HF method to the B i ( P b ) - S r - C a - Cu-O ceramics. In this p a p e r , grain o r i e n t a t i o n effects on s u p e r c o n d u c t i n g p r o p e r t i e s of the B i ( P b ) - S r - C a Cu-O ceramics h a v e been i n v e s t i g a t e d using t h e t a p e - c a s t i n g (TC) and h o ~ - f o r g t n g (HF) method. The g r a i n o r i e n t a t i o n e f f e c t s o n t h e s u p e r c o n d u c t i n g p r o p e r t i e s of TC÷HF samples are expected to exhibit e n h a n c e d Jc.
was statically applied aL 800~ along the thickness of t h e sample (the f o r g i n g axis). After c u t t i n g for measurements, samples were annealed at 850"C for I0 - 50 h in air. Evaluation of t h e TC÷HF samples was performed f o r the grain orientation factor, F. u s i n g the Lotgering method. Electrical c h a r a c t e r i s t i c s were measured by a s t a n d a r d f o u r - p r o b e method. 3. RESULTS AND DISCUSSION F i g u r e I shows X - r a y diffraction p a t t e r n s of (a) t h e p e r p e n d i c u l a r and ( b ) the parallel planes Bh~bo..Sr,.9,Ca2 ~Cu3.~O. i (a} TC+H.F
o
.~~, ..
Q
g'~
Press
c:~
~
o !
0
Press
Co) T C + m V (#c)
:
0
2. E X P E R I M E N T A L
The a p p r o p r i a t e a m o u n t s of Bi203, PbO, SrC03, Cat03 and CuO powders were mixed in molecular ratio of Bi~. 8,Pbo. 3,Sr~. 9 ~Ca2. o ~Cu,. o sO. % After calcined at 800"13 f o r 10 h, the mixtures were h e a t t r e a t e d at 85022 f o r 50 h to form t h e h i g h - T o phase of the ~ l - ~ r - t ~ a - ~ u - u system. The ceramlc powders were ball-milled i n t o a fine powder, and then milled t o g e t h e r with o r g a n i c formulations. T h e r e s u l t i n g s l u r r y was t a p e - r a n t u n d e r a doctor blade into 100 u m-thick g r e e n s h e e t on p o l y e t h y lene c a r r i e r s h e e t . Samples were c u t from the green s h e e t a n d a t h e r m o c o m p r e s s i o n bonding was applied to 50 - 10O sheets. The bonded s h e e t s were h e a t - t r e a t e d at 500"(; for 50 h to remove t h e organic formulation. A unlaxial ccmpressional l~ad
.= O) O F LAI,~
~ ~.
. I
19
20
30
40
50
60
29 [degree]
FIGURE 1 X-ray diffraction p a t t e r n s of (a) the pependicular (_L} and (b) the parallel ( / / ) planes, to the forging axis. of the TC*HF, a n d (c) the OF ~]i(Pb)-Sr-CaC u - O ceramh.s.
0921-4534DI/$03.50 O 1991 - Elsevier Science P~ 9lishcrs B.V. AH fighas reserved
/ Tape-casted and hot.forged superconducting Bi (Pb).Sr-Ca-Cu-O ceramics
T Seld et at
2426
to t h e f o r g i n g axis ( c o r r e s p o n d i n g to t h e c - a x i s ) of t h e TC÷HF, a n d (c) t h e o r d i n a r y f i r i n g ( a b b r e v i a t e d to "OF") s m a p l e s without o r i e n t a t i o n . An almost single p h a s e with t h e c-axls o r i e n t a t i o n of h l g h - T c p h a s e In B I - S r - e a - C u - O s y s t e m oc,uld be o b s e r v e d . The g r a i n o r i e n t a t i o n f a c t o r , F, was e s t i m a t e d as F = 0.9 f o r F i g . l (a). F i g u r e 2 shows t h e t e m p e r a t u r e d e p e n d e n c e of t h e r e s i s t i v i t y , o , f o r (a) t h e p e r p e n d i c u l a r p l a n e ( a b - plane} and (b) t h e parallel direction (c-axis), to t h e f o r g i n g axls, of t h e TC÷HF samples. The z e r o r e s i s t a n c e s t a t e ( o =0) was a c h i e v e d a t 104 K. 25
1.0 I Bi,~Pb~aSr,.,,Ca,.o,Cu,.~O,
8
0.8
&
0.6
e
0.4 0.2 0
I
'-°+ °
.~-
t5
I
0
50
100
150
200
250
Temperature [K] FIGURE 2 T e m p e r a t u r e d e p e n d e n c e of the r e s i s t i v i t y , O, f o r (a) t h e p e r p e n d i c u l a r (the a b - p l a n e ) a n d (b) t h e parallel (the c-ax~s), to t h e f o r g i n g axis, of t h e TC+HF. 10~
Bi,+~Pbo_~Sr,.gtCa2.mCu,.~O~
1¢
~
The a n l s o t o r o p y of p a t T c [ o n s e t ] in t h e p e r p e n d i c u l a r a n d the parallel p l a n e s to t h e f o r g i n g axis was a b o u t 45. Critical c u r r e n t d e n s i t y , J c [ a b ] a n d J c [ c ] , of t h e a h - p l a n e and t h e c - a x i s should he c o m p a r e d with Jc[OF] of t h e OF sample. The J c [ a b ] (=840 A/cm 2) a t 77 K u n d e r n o magnetic field f o r t h e TC÷HF samples was e l e v a t e d a b o u t 14 times a s l a r g e a s t h a t Jc[OF| (=60 A/cm ~) of u n o r l e n t e d (OF) sample. This d e m o n s t r a t e s t h a t t h e g r a i n o r i e n t a t i o n b y t h e t a p e - c a s t i n g and h o t - f o r g i n g (TC+HF) is efficacious f o r t h e e n h a n c e m e n t of t h e dc. I n s p i t e of h i g h o r i e n t a t i o n f a c t o r (F = 0.9), h o w e v e r , J c is not so h i g h . This seems to be c a u s e of t h e weak coupling of g r a i n b o u n d a r y . F i g u r e 3 shows t h e m a g n e t i c field d e p e n d e n c e of t h e critical c u r r e n t d e n s i t y , Jc, a t 77 K Por TC.HF a n d OF samples. T h e magnetic field was a p p l i e d on both p e r p e n d i c u l a r to t h e c u r r e n t a n d p e r p e n d i c u l a r or parallel t o t h e c-axis. I t c l e a r l y c o n f i r m s to be e n h a n c e d t h e dc[ab] u n d e r m a g n e t i c field b y t h e g r a i n o r i e n t a t i o n e f f e c t s . 4. CONCLUSIONS T h e g r a i n o r i e n t a t i o n e f f e c t s on t h e s u p e r c o n d u c t i n g p r o p e r t i e s of t h e B i ( P b ) - S r - C a - C u - O c e r a m i c s a r e s t u d i e d u s i n g combination t h e t a p e c a s t i n g (TC) method with t h e h o t - f o r g i n g (HF) method. The g r a i n o r i e n t a t i o n factor, F, of a b o u t 0.8 - 0.9 was estimated f r o m X - r a y d i f f r a c t i o n patterns. A s u p e r c o n d u c t i n g t r a n s i t i o n ( p = 0) a t 104 K was o b s e r v e d for t h e TC+HF samples. We also c o n f i r m e d t h e a n i s o t o r o p y in t h e r e s i s t i v i t y of t h e a b - p l a n e a n d c-axis of TC÷HF samples. T h e c r i t i c a l c u r r e n t d e n s i t y , J c [ a b ] , was e n h a n c e d 14 times a s t h e Jc[OF] of t h e u n o r i e n t e d samples b y t h e g r a i n o r i e n t a t i o n effects. REFERENCES
c-axts B
1. T. T a k e n a k a , ft. Noda, A. Yoneda, K. S a k a t a , J p n . J. Appl. P h y s . 27~ (7), (1988) L1209
i0
2. T. T a k e n a k a , H. Noda a n d K. Sakata, Ceramic
n
l
R
0.2
!
0.4
I
i
~.6
0.8
Magnetic field, B [3"] FIGURE 3 Magnetic field d e p e n d e n c e of the ccit~c.al c u r r e n t d e n s i t y , Jc, of t h e TC+HF and the OF.
3. K. Togano, H. Kumakura, H. Naeda, N. Irisawa, E. Yanag/sa~,a, d. Shimoyama, T. Ner~moto, J p n . J. AppL Phys. 2_8 (1989) L95. 4. E. Yamnag[sawa, T. Nor[moto, D. R. Dietderich, Ho N~!ma~ura, K. Togano, H. Maeda, AppI. P h y s . Lett. 5_4 (25), 1t989} 2602. 5. U. Endo, S+ K¢)'C,+~,;a~ ~. KawaL Jpn. d. Appl. P h y s . 28 (1989} L J"~':~ G,~.