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Melt processing and oxygen doping of bismuth superconductors
PhysicaC 162-164 (1989) 893-894 North-Holland
MELT PROCESSINGAND OXYGENDOPING OF BISMUTH SUPERCONDUCTORS
M. PEUCKERT, W. BECKER, J. BOCK, B. HETTICH, H.-W. NEUMULLER+ and M. SCHWARZ Hoechst AG, Postf. 800320, D-6230 Frankfurt/M. 80, F.R.G. +Siemens AG, Postf. 3240, D-8520 Erlangen l , F.R.G. Bi based superconductors with I , 2 and 3 80-90 K and lOO-llO K, respectively. The thesized by special melt processes. Melt material which carries current densities
CuOo-layers have been prepared with Tc values of 60-75 K, compounds Bi2(Sr,Ca)2Cu06+x and Bi2Sr2CaCu208+x were synprocessed Bi2Sr~CaCu2Oa+v can be obtained as a dense bulk • in the range of ~ lO,O00v ATcm2 up to 8 T magn. f i e l d at 4 K.
CaO
I. INTRODUCTION Since the discovery of the Bi family of high Tc superconductors by von SchneringI and Maeda2 many attempts have been made to increase the
Ca7BI6016\ ~
c r i t i c a l temperature by either heating close to
cL2cu03
the melting point of the material 3 or by adding
t\
/i / i
.,,o.
PbO as a f l u x 4-6. In the present investigation methods were developed to prepare single phase
BiOl.5 ~-----~"~'--'--/fL_..~_~ .... ~........ ~
material of the three i n i t i a l members of the series of Bi superconductors.
s~B~4
-k
II
-
I
-
OuO
/
2. EXPERIMENTAL Experimental methods have been described
previ0usly 7'8.
SrO
3. RESULTSAND DISCUSSION Figure I shows the phases which are known so
FIGURE 1
Bi-Sr-Ca-Cu-O system with (Ca,Sr)CuO 2 and HTC phases with I , 2 and 3 CuO2 layers
far in the quasiquaternary system Bi-Sr-Ca-Cu-O. Three superconducting phases Bi2Sr2_xCan+xCUn+lOv with n=O, l and 2 can be prepared. M i s c i b i l i t y
D't
ranges have been determined as about 0 ( x < 0.7 for n=O and -0.3
l.O for n=l.
The CuO2 single layer compound with n=O has been synthesized by 2 routes: reaction of a
~
SIW,twdwwj
-o-
Z"
B-
Mt4~
./
1 mT
- 0,006
- 0,006
g .o'''''u'''''G'''''G""'" ~....d"
- g.008
stoichiometric mixture of the precurser oxides at 800-820 °C in air and by quenching stoichiometric oxide melt, m i l l i n g and annealing at 800 °C in a i r . With a Sr:Ca ratio of 2:1XRD analysis showed that about 85 % of the material is, in fact, the single layer compound; SQUID
0921--4534/89/$03.50 © Elsevier Science Publishers B.V. (North-Holland)
-0.m -0.012 20
I,0
,O
IlO
: 100
Temoerolure (K)
FIGURE 2 SQUID measurement of Bi2Srl.3Cao. 7CuO6+x
" ~O
" 1~
M. Peuckert et aL / Melt processing and oxygen doping of bismuth superconductors
894
data led to around 70 vo].-% superconducting
While i t is well known that Pb doping enhan-
phase at 60 K, see figure 2. When a BiSrCaCuO-2212 mixture is melted at
ces the formation of Bi2Sr2Ca2CU3OlO+x and leads to a Tc of 105-110 K6, the same superconducting
]]DO °C, solidified and then annealed at 815 °C
properties could be achieved starting with a
in a i r , bulk superconducting material is formed
1112 composition and heating i t at 870 °C for
which is single phase 8i2Sr2CaCu208+x according to XRD. I t can be broken and milled to powder.
80 h and then cycling between 870 °C and 600 °C.
The phase transformation from the amorphous
4. CONCLUSIONS
melt to the pure double layer compound follows
Melt processes are advantageous for the syn-
a complicated reaction sequence involving CuDx and Bi2(Sr,Ca)2Cu06+X as intermediates and is strongly depending on the oxidation state of the
thesis of Bi2(Sr,Ca)2Cu06+x and Bi2Sr2CaCu208+x. Doping is important in order to achieve high Tc values, especially, Ca for Sr in 2201, oxygen
material that increases from formal Cu+I'5 to
in 2212 and Pb for Bi in 2223 compound. The 0
Cu+2"2. The Tc of the 22]2 compound decreases
content also strongly affects the phase trans-
from 90 K to 75 k with increasing oxygen index
formation from amorphous material to dense 2212
from 8.09 to 8.23.
superconductor in the melt process.
On the dense material current densities of 13~OOO A/cm2 in 0 T and 6~000 A/cm2 in 8 T
ACKNOWLEDGEMENTS
magnetic f i e l d were measured at 4.2 K, while at 30 K only ]~OOOA/cm2 in 4 T were found,
The authors like to thank S. Elschner, K. Magerkurth, E. Paulus and R. Reichiing.
see figure 3. REFERENCES 14000
I. H. G. yon Schnering et a l . , Angew. Chem. Int. Ed. Engl. 27 (1988) 574.
E 12000 U
2. H. Maeda, FED HiTcSc-ED Workshop, Miyagi-Zao, June 2-4 (1988) 3.
p
3. J. M. Tarascon et a l . , Phys. Rev. B 38 (1988) 8885.
t0000 l U '~
4. S. M. Green et aI., Phys. Rev. B 38 (1988) 5016.
8000[ T-4,2K
600, F
X
X
X
5o M. Takano et a l . , Jap. J. AppI. Phys. 27
(]988) LI041.
X
6. U. Endo, S. Koyama and T. Kawai, Jap. d. Appl. Phys. 27 (1988) L1476.
4000
7. J. Bock and E. Preisler, Proc. MRS ]989 Spring Meeting, San Diego, April 24-29, 1989.
2000 H,..._ .. 0
•
0
!
t
•
I
2
•
I
3
,
I
4
T-30K
8. M. Peuckert, J. Bock, B. Hettich, M. Schwarz, ]. ECerS Conf., Maastricht, June 18-23, ]989.
~
•
5
B
6
7
(T)
FIGURE 3 Current densities of bulk 2212 material
B
MELT PROCESSINGAND OXYGENDOPING OF BISMUTH SUPERCONDUCTORS
M. PEUCKERT, W. BECKER, J. BOCK, B. HETTICH, H.-W. NEUMULLER+ and M. SCHWARZ Hoechst AG, Postf. 800320, D-6230 Frankfurt/M. 80, F.R.G. +Siemens AG, Postf. 3240, D-8520 Erlangen l , F.R.G. Bi based superconductors with I , 2 and 3 80-90 K and lOO-llO K, respectively. The thesized by special melt processes. Melt material which carries current densities
CuOo-layers have been prepared with Tc values of 60-75 K, compounds Bi2(Sr,Ca)2Cu06+x and Bi2Sr2CaCu208+x were synprocessed Bi2Sr~CaCu2Oa+v can be obtained as a dense bulk • in the range of ~ lO,O00v ATcm2 up to 8 T magn. f i e l d at 4 K.
CaO
I. INTRODUCTION Since the discovery of the Bi family of high Tc superconductors by von SchneringI and Maeda2 many attempts have been made to increase the
Ca7BI6016\ ~
c r i t i c a l temperature by either heating close to
cL2cu03
the melting point of the material 3 or by adding
t\
/i / i
.,,o.
PbO as a f l u x 4-6. In the present investigation methods were developed to prepare single phase
BiOl.5 ~-----~"~'--'--/fL_..~_~ .... ~........ ~
material of the three i n i t i a l members of the series of Bi superconductors.
s~B~4
-k
II
-
I
-
OuO
/
2. EXPERIMENTAL Experimental methods have been described
previ0usly 7'8.
SrO
3. RESULTSAND DISCUSSION Figure I shows the phases which are known so
FIGURE 1
Bi-Sr-Ca-Cu-O system with (Ca,Sr)CuO 2 and HTC phases with I , 2 and 3 CuO2 layers
far in the quasiquaternary system Bi-Sr-Ca-Cu-O. Three superconducting phases Bi2Sr2_xCan+xCUn+lOv with n=O, l and 2 can be prepared. M i s c i b i l i t y
D't
ranges have been determined as about 0 ( x < 0.7 for n=O and -0.3
l.O for n=l.
The CuO2 single layer compound with n=O has been synthesized by 2 routes: reaction of a
~
SIW,twdwwj
-o-
Z"
B-
Mt4~
./
1 mT
- 0,006
- 0,006
g .o'''''u'''''G'''''G""'" ~....d"
- g.008
stoichiometric mixture of the precurser oxides at 800-820 °C in air and by quenching stoichiometric oxide melt, m i l l i n g and annealing at 800 °C in a i r . With a Sr:Ca ratio of 2:1XRD analysis showed that about 85 % of the material is, in fact, the single layer compound; SQUID
0921--4534/89/$03.50 © Elsevier Science Publishers B.V. (North-Holland)
-0.m -0.012 20
I,0
,O
IlO
: 100
Temoerolure (K)
FIGURE 2 SQUID measurement of Bi2Srl.3Cao. 7CuO6+x
" ~O
" 1~
M. Peuckert et aL / Melt processing and oxygen doping of bismuth superconductors
894
data led to around 70 vo].-% superconducting
While i t is well known that Pb doping enhan-
phase at 60 K, see figure 2. When a BiSrCaCuO-2212 mixture is melted at
ces the formation of Bi2Sr2Ca2CU3OlO+x and leads to a Tc of 105-110 K6, the same superconducting
]]DO °C, solidified and then annealed at 815 °C
properties could be achieved starting with a
in a i r , bulk superconducting material is formed
1112 composition and heating i t at 870 °C for
which is single phase 8i2Sr2CaCu208+x according to XRD. I t can be broken and milled to powder.
80 h and then cycling between 870 °C and 600 °C.
The phase transformation from the amorphous
4. CONCLUSIONS
melt to the pure double layer compound follows
Melt processes are advantageous for the syn-
a complicated reaction sequence involving CuDx and Bi2(Sr,Ca)2Cu06+X as intermediates and is strongly depending on the oxidation state of the
thesis of Bi2(Sr,Ca)2Cu06+x and Bi2Sr2CaCu208+x. Doping is important in order to achieve high Tc values, especially, Ca for Sr in 2201, oxygen
material that increases from formal Cu+I'5 to
in 2212 and Pb for Bi in 2223 compound. The 0
Cu+2"2. The Tc of the 22]2 compound decreases
content also strongly affects the phase trans-
from 90 K to 75 k with increasing oxygen index
formation from amorphous material to dense 2212
from 8.09 to 8.23.
superconductor in the melt process.
On the dense material current densities of 13~OOO A/cm2 in 0 T and 6~000 A/cm2 in 8 T
ACKNOWLEDGEMENTS
magnetic f i e l d were measured at 4.2 K, while at 30 K only ]~OOOA/cm2 in 4 T were found,
The authors like to thank S. Elschner, K. Magerkurth, E. Paulus and R. Reichiing.
see figure 3. REFERENCES 14000
I. H. G. yon Schnering et a l . , Angew. Chem. Int. Ed. Engl. 27 (1988) 574.
E 12000 U
2. H. Maeda, FED HiTcSc-ED Workshop, Miyagi-Zao, June 2-4 (1988) 3.
p
3. J. M. Tarascon et a l . , Phys. Rev. B 38 (1988) 8885.
t0000 l U '~
4. S. M. Green et aI., Phys. Rev. B 38 (1988) 5016.
8000[ T-4,2K
600, F
X
X
X
5o M. Takano et a l . , Jap. J. AppI. Phys. 27
(]988) LI041.
X
6. U. Endo, S. Koyama and T. Kawai, Jap. d. Appl. Phys. 27 (1988) L1476.
4000
7. J. Bock and E. Preisler, Proc. MRS ]989 Spring Meeting, San Diego, April 24-29, 1989.
2000 H,..._ .. 0
•
0
!
t
•
I
2
•
I
3
,
I
4
T-30K
8. M. Peuckert, J. Bock, B. Hettich, M. Schwarz, ]. ECerS Conf., Maastricht, June 18-23, ]989.
~
•
5
B
6
7
(T)
FIGURE 3 Current densities of bulk 2212 material
B