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A new superconducting series Cu0.5B0.5SrBaR0.6Ca0.4Cu2O7
PHYSICA ELSEVIER
Physica C 341-348 (2000) 391 394 www.elsevier.nl/Iocate/physc
A new superconducting
s e r i e s Cuo.sBo.~SrBaRo.6Cao.4Cu207
G. C. Che. G. D. Liu, F, Wu, H. C h e n , S. L. Jia, C. Dong and Z. X. Zhao National Laborat, ory ior Superconductivity, Institute of Physics, Chinese A(',adcnty of Scien(:,~s, B,~iiing 11100811. P.R. China Abstract: The formation of (R,B)-1212 phase and Super(:onductivity in Cu0.sB0.sSrBMI.0.GCa~).~Cu?()T system were investigated ( R = rare e.artit elements). It is found that in this system, (I/.,B)- 1212 l)h;Is(~ can be iorme.d For R=La, Pr, N(t, Sin, Eu, Gd, Y, Dy, Ho, Er, T m and Yb except for R.=C(; ;rod Tt). T,. of the (R,B)-1212 phase increses with the decrease of t/, atomic radius for La (29 K), Nd (43 K), Sm(49 K), Eu(54 K), Gd(66 K) and Dy(74 K), and keeps nearly a constant value of 75 K for R=Y. Ho. Er. T m and Yb. (R,B)-1212 phase for R = P r (:an be formed also, but it, is not sui)ereolldueting. Kcywor(ts: llew cuprate superconductor, superconductivity, component substitution
1. I N T R O D U C T I O N Wc r,q>orI,cd first B()a-contaiifing cuml>,)~md YSr2Cu3_ rB:,.(): [1] and studied its c,rystal stru,> tm'e[1], modulation structure[2-4], combination substitution of oxyanion groups[5-6] and supereonductivity.
._._/k
_._.,j ~
:,-a
~j(
Pr
~ J k
J
~ .
The substitution of Ca for Y has proved to b c a useful way to adjust carrier concentration in many series of superconductors. For examt)le, in (Ph,M) and (Hg,M)-1212 series. Slater ~t ,/.l. r~q)orted an improved T~. around 60 K in (Y. C;~)BaSrCu3_:rB.r()yI7]. For most series of tim substitution of Ca for Y, the oi)timmn content of Ca was reported to be 0.3(I.5. In this paper, superconductivity and the formation of (R,B)-1212 phase were investigated in Cu().~B0.~SrBaI~).6Ca0.4CuzO7 (RSrBaCuBO)
__..~
_ J
/~JL_._..
_
_
C~d ~'¢"
m
~. ~,.
Y
.~
L.,
2_2
S(~l'ies.
Nd Sm
_
L.,
Jk
/t,.
t
2. E X P E R I M E N T A L Ploycrystalline samples of Cuo.5Bo.~SrBaR,o.G Cao.4Cu207(RSrBaCuB()) were prepared by mixing high-Imrity powders of II,~,()3 (except 0921-4534/00/$ - see front matter © 2000 Elsevier Science B.V PII S0921-4534(00)00519-0
t! _ _ , , ~
_
AJ~
J
i
2O
40 20
i 60
(Degree)
Figm'c 1. XRD patt,,u'ns of Cn~I ~B~.~SrBaR.I G C;1,0.4 C l l 2 ( ) 7 s y s t , e l n . All rights reserved.
392
G.C. Che et al./Physica C 341-348 (2000) 391-394
1 1.6 3.90
11.5
c 3,88
•
•
O
•
•
O •
O
.<
•
•
•
11.4
O
o m 3.86
o
o
11.3
a
o o
11.2
0
3.84
0
R=
0
0
I
I
I
I
I
I
I
I
I
I
I
I
La
Pr
Nd
Sm
Eu
Gd
Dy
Y
Ho
Er
Tm
Yb
11.1
Figure 2. Lattice parameters in Cuo.sBo.5SrBaRo.6Cao.4Cu2()7 series.
100
80 O •
O O
O
O
O
6O O v
O O
I_.Y 40
o
=
T c (0)
•
=
T (onset)
O 20
0 R = La r(A)=1.160
I
I
I
I
I
!
i
!
I
Pr
Nd
Sm
Eu
Gd
Dy
Y
Ho
Er
Tm
Yb
1.066
1.0S3
1.027
1.019
1.016
1.004
0.994
0.985
1.t26
1.109
t.079
/
Figure 3. T~ vs. x in Cuo.5Bo.~SrP,:d%.6Cao.4Cu2()7 series.
G.C Che et al./Physica C 341-348 (2000) 391-394
393
1.5
R.IETVELD programs were used for lattice parameter cak:ulations and structure refinements. Resistivity-temperature curw.'s were measured })y the conventional four-probe technique.
1.0 at
3. R E S U L T S 0.5
.
0.0 50
I00
.
.
.
150
200
250
Temperature(K)
Figure 4. R-T curves in Cuo.sB0.aSrBaR0.G Ca0.4Cu_,()r series for R = L a , Pr,Nd,Sm,Eu and Gd. I. 0 0 ¢%,m,b~,C%,Cu,O,
0.75
0. 50 0.25
~
¥
.
!4o Ef
AND
DISCUSSION
XRD patterns of RSrBaCuBO series shown in Fig.1 indicate that(R,B)-1212 phase can be formed For R = L a , Pr, Nd, Sin, Eu, Gd, Y, Dy, Ho, Er, T m and Yb except for R : C e and Tb. The lattice parameter of (R,B)-1212 phase strewn in Fig.2 indicate that the values of both lattice, parameter a and (: decrease with the decrease of R. atomic radius. T(. vs. x and R-T curw~s are shown in Fig.3,4 and 5, respectively. They i11dicat;e t;liat. Tc of the (R,B)-1212 phase increses with the decrease of R atomic radius for La (29K), Nd (43 K), Sm(49 K), Eu(54 K), Gd(66 K ) a n d Dy(74 K), and keeps nearly a constant value of 75 K tk)r R=Y, Ho, Er, T m and Yb. The obtained highest T~. value is T~(0)=79 K when R = E r . It is similar to R-123 series that (R,B)-1212 phase for R = P r can be tbrmed, but it is not superconducting.
I'm Yb O. 0 0
50
'
I00
'
150
10
f
J
200
Temperature(K)
Fig. 5. R-T curves in series Cu0.sBo.sSrBaRo.6 Cao.4Cu207 series for R=Dy, Y, Ho, Er, T m and Yb. for R = P r , where P r 6 O n was used), SrCOa, BaC()3, CuO and B203 in an agate mortar, calcining at. 900°C in air for 40 h, gringing it in the mortar again , pressing it into a pellet, and then si]~tering at 940-980°C in air for 50 h. After sintering, the pellet was cooled slowly at a rate of 30°C/h to room temperature in a furnace. In order to improve sample quality, some samples were annealed in an atmosphere of O2 at 400°C for 40 h. X-ray powder diffraction examination was performed using a M18X-AHF type diffractometer with Cu K~,-radiation. FINAX, LAZY and
5
f
_
x=,5
0
0
5o
loo
150
2oo
2so
3o0
Temperature(K)
Figure 6. Some typical R-T curves in Cuo.5Bo.5 Sr2_x Ba~Yo.6Cao.4Cu2Oy series. The samples of Cuo.sBo.sSrBaYo.6Cao.4Cu~O~/ (YCaSrBaCuBO) series were preparcd also for investigating the effect of Ba or Sr (:ontent on superconductivity. Our results indicate that the samph!s sintered at 945-96()°C for 50 h are single
394
G.C Che et aL/Physica C 341-348 (2000) 391-394
or n e a r l y single-phasic w h e n x = 0 . 5 -
1.5. R - T
curves for this series are shown in Fig.
6.
values are 43, 66, 74, 76 and 74 K for the samples with x =
0.5, 0.75, 1.0, 1.25 and 1.5, respec-
tively. T~ values of C u 0 . s B 0 . s S r 2 _ z B a ~ Y C u 2 O y u n d o p e d by C a are 13, 39, 47, 46 and 45 K for the s a m p l e s w i t h x = 0.5, 0.75, 1.0, 1.25 and 1.5, respectively. T h i s indicates t h a t the carrier conc c n t r a t i o n in Y C a B a C u B O is a d j u s t e d not only by t h e s u b s t i t u t i o n of C a for Y, b u t also by Ba or Sr c o n t e n t .
T h e m e c h a n i s m of a d j u s t i n g carrier
c o n c e n t r a t i o n by the s u b s t i t u t i o n of B a for Sr is u n k n o w n .
It is p r o b a b l y due to the coupling
'change b e t w e e n C u 0 2 planes.
REFERENCES
Tc [1] W. J. Zhu, J. J. Yue, Y. Z. Hum~g and Z, X. Zlmo, Physica C 205 (1993) 118. [2] J. Q. Li, W. J. Zhu, Z. X. Zhao and D. L. Yin, Solid StaLe Coramuni. 85 (1993) 739. [3] J. Q. Li, F. H. Liand Z. X. Zhao, Phys. Roy. B 48 (1993) 1333. [4] J. Q. Li, H. Chert and Z. X. Zhao, Physh:a C 233 (1994) 40. [5] H. Dcng, C. Dong, J. C. Shen, F. Wu, H. Chcn, S. L. Jia, G. C. Che and Z. X. Zhao, Physica C 278 (1997) 107. [6] H. Deng, C. Dong, Y. R. Zhou, F, Wu, H. Chen, S. L. Jia, J. C. Chert, G. S. Yuan and Z. X. Zhao, Physica C 296 (1998) 225.
[7] P. R. Slater and C. Greaves, Physica C 215(1993) 191.
Physica C 341-348 (2000) 391 394 www.elsevier.nl/Iocate/physc
A new superconducting
s e r i e s Cuo.sBo.~SrBaRo.6Cao.4Cu207
G. C. Che. G. D. Liu, F, Wu, H. C h e n , S. L. Jia, C. Dong and Z. X. Zhao National Laborat, ory ior Superconductivity, Institute of Physics, Chinese A(',adcnty of Scien(:,~s, B,~iiing 11100811. P.R. China Abstract: The formation of (R,B)-1212 phase and Super(:onductivity in Cu0.sB0.sSrBMI.0.GCa~).~Cu?()T system were investigated ( R = rare e.artit elements). It is found that in this system, (I/.,B)- 1212 l)h;Is(~ can be iorme.d For R=La, Pr, N(t, Sin, Eu, Gd, Y, Dy, Ho, Er, T m and Yb except for R.=C(; ;rod Tt). T,. of the (R,B)-1212 phase increses with the decrease of t/, atomic radius for La (29 K), Nd (43 K), Sm(49 K), Eu(54 K), Gd(66 K) and Dy(74 K), and keeps nearly a constant value of 75 K for R=Y. Ho. Er. T m and Yb. (R,B)-1212 phase for R = P r (:an be formed also, but it, is not sui)ereolldueting. Kcywor(ts: llew cuprate superconductor, superconductivity, component substitution
1. I N T R O D U C T I O N Wc r,q>orI,cd first B()a-contaiifing cuml>,)~md YSr2Cu3_ rB:,.(): [1] and studied its c,rystal stru,> tm'e[1], modulation structure[2-4], combination substitution of oxyanion groups[5-6] and supereonductivity.
._._/k
_._.,j ~
:,-a
~j(
Pr
~ J k
J
~ .
The substitution of Ca for Y has proved to b c a useful way to adjust carrier concentration in many series of superconductors. For examt)le, in (Ph,M) and (Hg,M)-1212 series. Slater ~t ,/.l. r~q)orted an improved T~. around 60 K in (Y. C;~)BaSrCu3_:rB.r()yI7]. For most series of tim substitution of Ca for Y, the oi)timmn content of Ca was reported to be 0.3(I.5. In this paper, superconductivity and the formation of (R,B)-1212 phase were investigated in Cu().~B0.~SrBaI~).6Ca0.4CuzO7 (RSrBaCuBO)
__..~
_ J
/~JL_._..
_
_
C~d ~'¢"
m
~. ~,.
Y
.~
L.,
2_2
S(~l'ies.
Nd Sm
_
L.,
Jk
/t,.
t
2. E X P E R I M E N T A L Ploycrystalline samples of Cuo.5Bo.~SrBaR,o.G Cao.4Cu207(RSrBaCuB()) were prepared by mixing high-Imrity powders of II,~,()3 (except 0921-4534/00/$ - see front matter © 2000 Elsevier Science B.V PII S0921-4534(00)00519-0
t! _ _ , , ~
_
AJ~
J
i
2O
40 20
i 60
(Degree)
Figm'c 1. XRD patt,,u'ns of Cn~I ~B~.~SrBaR.I G C;1,0.4 C l l 2 ( ) 7 s y s t , e l n . All rights reserved.
392
G.C. Che et al./Physica C 341-348 (2000) 391-394
1 1.6 3.90
11.5
c 3,88
•
•
O
•
•
O •
O
.<
•
•
•
11.4
O
o m 3.86
o
o
11.3
a
o o
11.2
0
3.84
0
R=
0
0
I
I
I
I
I
I
I
I
I
I
I
I
La
Pr
Nd
Sm
Eu
Gd
Dy
Y
Ho
Er
Tm
Yb
11.1
Figure 2. Lattice parameters in Cuo.sBo.5SrBaRo.6Cao.4Cu2()7 series.
100
80 O •
O O
O
O
O
6O O v
O O
I_.Y 40
o
=
T c (0)
•
=
T (onset)
O 20
0 R = La r(A)=1.160
I
I
I
I
I
!
i
!
I
Pr
Nd
Sm
Eu
Gd
Dy
Y
Ho
Er
Tm
Yb
1.066
1.0S3
1.027
1.019
1.016
1.004
0.994
0.985
1.t26
1.109
t.079
/
Figure 3. T~ vs. x in Cuo.5Bo.~SrP,:d%.6Cao.4Cu2()7 series.
G.C Che et al./Physica C 341-348 (2000) 391-394
393
1.5
R.IETVELD programs were used for lattice parameter cak:ulations and structure refinements. Resistivity-temperature curw.'s were measured })y the conventional four-probe technique.
1.0 at
3. R E S U L T S 0.5
.
0.0 50
I00
.
.
.
150
200
250
Temperature(K)
Figure 4. R-T curves in Cuo.sB0.aSrBaR0.G Ca0.4Cu_,()r series for R = L a , Pr,Nd,Sm,Eu and Gd. I. 0 0 ¢%,m,b~,C%,Cu,O,
0.75
0. 50 0.25
~
¥
.
!4o Ef
AND
DISCUSSION
XRD patterns of RSrBaCuBO series shown in Fig.1 indicate that(R,B)-1212 phase can be formed For R = L a , Pr, Nd, Sin, Eu, Gd, Y, Dy, Ho, Er, T m and Yb except for R : C e and Tb. The lattice parameter of (R,B)-1212 phase strewn in Fig.2 indicate that the values of both lattice, parameter a and (: decrease with the decrease of R. atomic radius. T(. vs. x and R-T curw~s are shown in Fig.3,4 and 5, respectively. They i11dicat;e t;liat. Tc of the (R,B)-1212 phase increses with the decrease of R atomic radius for La (29K), Nd (43 K), Sm(49 K), Eu(54 K), Gd(66 K ) a n d Dy(74 K), and keeps nearly a constant value of 75 K tk)r R=Y, Ho, Er, T m and Yb. The obtained highest T~. value is T~(0)=79 K when R = E r . It is similar to R-123 series that (R,B)-1212 phase for R = P r can be tbrmed, but it is not superconducting.
I'm Yb O. 0 0
50
'
I00
'
150
10
f
J
200
Temperature(K)
Fig. 5. R-T curves in series Cu0.sBo.sSrBaRo.6 Cao.4Cu207 series for R=Dy, Y, Ho, Er, T m and Yb. for R = P r , where P r 6 O n was used), SrCOa, BaC()3, CuO and B203 in an agate mortar, calcining at. 900°C in air for 40 h, gringing it in the mortar again , pressing it into a pellet, and then si]~tering at 940-980°C in air for 50 h. After sintering, the pellet was cooled slowly at a rate of 30°C/h to room temperature in a furnace. In order to improve sample quality, some samples were annealed in an atmosphere of O2 at 400°C for 40 h. X-ray powder diffraction examination was performed using a M18X-AHF type diffractometer with Cu K~,-radiation. FINAX, LAZY and
5
f
_
x=,5
0
0
5o
loo
150
2oo
2so
3o0
Temperature(K)
Figure 6. Some typical R-T curves in Cuo.5Bo.5 Sr2_x Ba~Yo.6Cao.4Cu2Oy series. The samples of Cuo.sBo.sSrBaYo.6Cao.4Cu~O~/ (YCaSrBaCuBO) series were preparcd also for investigating the effect of Ba or Sr (:ontent on superconductivity. Our results indicate that the samph!s sintered at 945-96()°C for 50 h are single
394
G.C Che et aL/Physica C 341-348 (2000) 391-394
or n e a r l y single-phasic w h e n x = 0 . 5 -
1.5. R - T
curves for this series are shown in Fig.
6.
values are 43, 66, 74, 76 and 74 K for the samples with x =
0.5, 0.75, 1.0, 1.25 and 1.5, respec-
tively. T~ values of C u 0 . s B 0 . s S r 2 _ z B a ~ Y C u 2 O y u n d o p e d by C a are 13, 39, 47, 46 and 45 K for the s a m p l e s w i t h x = 0.5, 0.75, 1.0, 1.25 and 1.5, respectively. T h i s indicates t h a t the carrier conc c n t r a t i o n in Y C a B a C u B O is a d j u s t e d not only by t h e s u b s t i t u t i o n of C a for Y, b u t also by Ba or Sr c o n t e n t .
T h e m e c h a n i s m of a d j u s t i n g carrier
c o n c e n t r a t i o n by the s u b s t i t u t i o n of B a for Sr is u n k n o w n .
It is p r o b a b l y due to the coupling
'change b e t w e e n C u 0 2 planes.
REFERENCES
Tc [1] W. J. Zhu, J. J. Yue, Y. Z. Hum~g and Z, X. Zlmo, Physica C 205 (1993) 118. [2] J. Q. Li, W. J. Zhu, Z. X. Zhao and D. L. Yin, Solid StaLe Coramuni. 85 (1993) 739. [3] J. Q. Li, F. H. Liand Z. X. Zhao, Phys. Roy. B 48 (1993) 1333. [4] J. Q. Li, H. Chert and Z. X. Zhao, Physh:a C 233 (1994) 40. [5] H. Dcng, C. Dong, J. C. Shen, F. Wu, H. Chcn, S. L. Jia, G. C. Che and Z. X. Zhao, Physica C 278 (1997) 107. [6] H. Deng, C. Dong, Y. R. Zhou, F, Wu, H. Chen, S. L. Jia, J. C. Chert, G. S. Yuan and Z. X. Zhao, Physica C 296 (1998) 225.
[7] P. R. Slater and C. Greaves, Physica C 215(1993) 191.