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Superconductivity in the (Dy1−xPrx) Ba2Cu2Oy system
PHYSICA
Physica C 182 (1991) 153-156 North-Holland
Superconductivity in the (Dy
Ba2Cu2Oysystem
X.W. Cao, C.Y. Wu and J.C. H o Departments of Physics and Chemistry and National Institute for Aviation Research, Wichita State University, Wichita, KS 67208, USA Received 28 June 1991 Revised manuscript received 28 August 1991
A series of orthorhombic (Dyt _xPrx)Ba2Cu3Oy samples with x = 0-1.0 were synthesized and characterized by XRD, DTA and electrical resistivity measurements. Pr-doping suppresses the superconducting transitions more or less linearly to a complete quenching at x-~ 0.6. Meanwhile, increase in normal-state resistivities and their deviation from a linear temperature dependence begin to show up near x -~ 0.3-0.4, beyond which a semiconducting behavior prevails. These results are discussed in conjunction with those previously reported for isomorphic compounds (Yt _~Prx) Ba2Cu3Oy, ( Eut _xPr~) Ba2Cu3Oy, and ( Gd~ _~Pr~) Ba2Cu30 r
It has been well established that the orthorhombic structure of YBa2Cu3Ov(Y- 123) is retained when
yttrium is replaced by most of the rare earth (RE) elements excluding Ce, Tb, or Pm. The resulting
~.000 c N T S
/
v
800
s E c 600
400
~
r,~
~
(..q
20
25
30
35
40
45
50
55
60
2 THETA
Fig. 1. A typical X-ray diffraction pattern for x = 0.15, corresponding to the orthorhombic 123-structure. 0921-4534/91/$03.50 © 1991 Elsevier Science Publishers B.V. All rights reserved.
154
X. W. Cao et al. / Superconductivity in the (Dyl_xPr~)Ba2Cu30r system 0.05
x=0.3
"•
0.00-
1080-
b
o
o c o
o
o
o
o
o
x
o
o
1040
-0. o5-
0 o
(by1-xPr,)Ba2CusOy
4J
F- 1000 t-
o
Tp
Te
-0. 10-
960
o.o
-0.15
~oo
s~o
,
,
0.2
0.4
J
0.'6
9do
Tp
1.o 9go
Temperature
~obo
lo~o
1loo
(°C)
Fig. 2. A typical DTA trace for defining the extrapolated-onset (Te) and peak (Tp) temperatures of peritectic melting, with their dependence on x shown in the inset. REBa2Cu30,, (RE- 123) compounds exhibit almost identical superconducting transitions with T~> 90 K except for the case where R E = Pr [ 1 ]. Mechanisms for the absence of superconductivity in Pr-123 and a well documented depression of Tc in Y-123 by Prsubstitution [ 1,2 ] are yet to be clarified. Two mechanisms with various experimental evidence [ 2 ] have been proposed: (1) tetravalent or mixed-valent Pr-induced hole filling or localization of mobile holes in the conducting Cu20 planes [ 3 ] and (2) magnetic pair breaking through the hybridization of trivalent Pr 4f and O 2p states of CuO2 planes [4]. They also reflect the uncertainty in the valence of Pr-ions [ 5 ]. The first mechanism and the higher-valent state are further supported by the studies on superconducting (Pr.sCa.5) BazCu3Oy [ 6 ] and (Y~ ..... .vPrxCay) Ba2Cu3Oy [ 7 ]. Superconductivity is suggested to be enhanced by compensating the detrimental Pr-effect through hole doping with Ca 2÷ ions. In the magnetic pair breaking mechanism, the exchange interaction is presumably a consequence of the fact that Pr 3+ has the largest radius among all magnetic RE 3+ ions. Indeed, no appreciable coupling is observed between the occurrence of super-
conductivity and magnetic interactions among rare earth ions with larger magnetic moments in superconducting RE-123. For example, the antiferromagnetic ordering of Gd 3+ in Gd-123 remains near 2.2 K when superconductivity is quenched through oxygen deficiency [ 8 ]. To better resolve these complicated but important issues, experimental results need to be derived from more systems. Several recent articles describe the x-dependence of the superconducting behavior of (Eul_xPrx)BazCu3Oy [9] and (Gdl_xPrx)Ba2Cu3Oy [2,10], in addition to (Yl_xPrx)Ba2Cu3Oy [2]. This work deals with another mixed system, (Dy~_xPrx)Ba2Cu3Oy, involving a heavy rare earth element Dy. A series of (Dyl_xPrx)-123 samples, with x = 0 , 0.02, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0, respectively, were synthesized by solidstate reactions from high-purity Dy203, Pr60~, BaCO3, and CuO. Thoroughly mixed ingredient powders for each sample were first calcined in air at 900 °C for 12 h. The product was reground and pelletized for two consecutive sintering processes of 940°C/12 h each. Following the second sintering, the sample was slowly cooled in 3 h to 600°C for a 4 h annealing in flowing oxygen, cooled again in 2 h
X. IV. Cao et al. / Superconductivity in the (Dy~_~PrABa2Cu30~ system 24
155
120 • • • m
21 18
100-
(Y,,Prx)Ba2Cu~Oy (Ref. ll) (Eu,.xPr~)BazCu~Oy (Ref. 9) (Gdt~Pr~)Ba2Cu~Oy (.Ref.10a) (DyhPrx)Ba2Cu~Oy (This work)
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x=0.90 1
x=0.80 x=0.70 x=0.60
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,,
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T (K) Fig. 3. Temperature dependence of electrical resistivity, also showing the superconducting transitions.
100 I
(Dyl-,Pr×)Ba2Cu30y 80-
&
To~ ¢
o
To~
60 13
0
40-
o.o
o.il
o'~
o.3
O.t4
0.15
X Fig. 5. Comparison of Tom variations with Pr content in four Prs u b s t i t u t e d systems.
$~0"
0.0
0.6
X
Fig. 4. Dependence of superconducting transition temperatures onx.
•
E c~
o
:>
0
0
>-, 3.5
-X
1
to 400 °C for another 8 h annealing, and finally cooled in 3 h to room temperature. X-ray powder diffraction patterns, as typified by fig. 1, correspond to an orthorhombic structure as expected. That each sample is practically of single phase is further verified by a rather clean peritectic melting-trace from differential thermal analysis in fig. 2, which also defines the extrapolated-onset (Te) and peak (Tp) temperatures for melting. The inset of fig. 2 shows the dependence of these temperatures on Pr-doping, with a maximum near x = 0 . 4 - 0 . 5 . Four-probe electrical resistivity measurements were made in a closed-cycle refrigerator. As shown in fig. 3, the results provide information concerning the normal-state resistivities and their temperature dependence, as well as the superconducting transitions for x < 0 . 6 . The reasonably narrow transition widths are given in fig. 4 in terms of Tee for the extrapolated-onset (cf. fig. 2), Tom for the middle point, and Teo for zero resistance. The non-substituted Dy123 yields a 93 K transition as previously reported. Increase in normal-state resistivities and their deviation from a linear temperature dependence at T>_ Tc begin to show up at x-~0.3-0.4, followed by a gradual change to a semiconducting behavior. Sim-
156
X. 146 Cao et at,./Superconductivity in the (Dyz_xPG)Ba2Cu3Oysystem
ilar observations have been made in (Yj_xPrx)-123 [la] and (Gd~_xPrx)-123 [10c]. Figure 5 compares the variations of Tcm among (Yl_,Pr,.)-I23 [11] (Eul_xPrx)-123 [9], (Gd~_,Pr,)-123 [10a], and (Dy~_xPrx)-123. A complete quenching of superconductivity occurs invariably near x=0.4-0.6. The effectiveness in Tc suppression by Pr-doping, however, appears to follow inversely with the ionic radii o f Y 3+, Eu 3+, G d 3+, and D y 3+.
Acknowledgement This work was supported by Ametek, Inc. and the Kansas Technology Enterprise Corporation. The authors would like to thank Yuanji Tang for his technical assistance.
References [ l ] (a) L. Soderholm, K. Zhang, D.G. Hinks, M.A. Beno, J.D. Jorgensen, C.U. Segre and I.K. Schuller, Nature 328 (1987) 604; (b) Y. Dalichaouch, M.S. Torikachvili, E.A. Early, B.W. Lee, C.L. Seaman, K.N. Yang, H. Zhou and M.B. Maple, Solid State Commun. 65 (1988) 1001. [2] For a recent account of numerous reports see, e.g., H.D. Yang, P.F. Chen, C.R. Hsu, C.W. Lee, C.L. Li and C.C. Peng, Phys. Rev. B 43 ( 1991 ) 10568, and references therein. [ 3 ] For early studies see ref. [ 1] and J. Zaanen, A.T. Paxton, O. Jepsen and O.K. Andersen, Phys. Rev. Lett. 60 (1988) 2685.
[4] For early studies see (a) J.J. Neumeier, M.B. Maple and M.S. Torikachvili, Physica C 156 (1988) 574; (b) J.S. Kang, J.W. Allen, Z.X. Shen, W.P. Ellis, J.J. Yeh, B.W. Lee, M.B. Maple, W.E. Spicer and I. Lindau, J. Less Common Met. 148 (1989) 121; (c) A. Kebede, C.S. Jee, J. Schwegler, J.E. Crow, T. Mihalisin, G.H. Myer, R.E. Salomon, P. Schlonmann, M.V. Kuric, S.H. Bloom and R.P. Guertin, Phys. Rev. B 40 (1989) 4453; (d) J.L. Peng, P. Klavins, R.N. Shelton, H.B. Radousky, P.A. Hahn and L. Bernardez, Phys. Rev. B 40 (1989) 4517. [ 5 ] For a summary see, e.g., M.B. Maple, N.Y. Ayoub, J. Beille, T. Bjornholm, Y. Dalichaouch, E.A. Early, S. Ghamaty, B.W. Lee, J.T. Markert, J.J. Neumeier, G. Nieva, L.M. Paulius, I.K. Schuller, C.L. Seaman and P.K. Tsai, Proc. '90 Int. Conf. Transport Prop. Supercond., Rio de Janeiro, Brazil (World Scientific, Singapore, 1990) p. 536. [6] D.P. Norton, D.H. Lowndes, B.C. Sales, J.D. Budai, B.C. Chakoumakos and H.R. Kerchner, Phys. Rev. Lett. 66 (1991) 1537. [7 ] J.J. Neumeier, T. Bjornholm, M.P. Maple and I.K. Schuller, Phys. Rev. Lett. 63 (1989) 2516. [8] (a) J.C. Ho, P.H. Hor, R.L. Meng, C.W. Chu and C.Y. Huang, Solid State Commun. 63 (1987) 711; (b) J.C. Ho, C.Y. Huang, P.H. Hor, R.L. Meng and C.W. Chu, Mod. Phys. Lett. B 1 (1988) 417. [9] K. Latka, A. Szytula, Z. Tomkowicz, A. Zygmunt and R. Duraj, Physica C 171 (1990) 287. [lO] (a) H. lwasaki, Y. Dalichaouch, J.T. Markert, G. Nieva, C.L. Seaman and M.B. Maple, Physica C 169 (1990) 146; (b) Z. Tomkowicz, K. Latka, A. Szytula, A. Bajorek, M. Balanda, R. Kmiec, R. Kruk and A. Zygmunt, Physica C 174 (1991) 71; (c) 1. Das, E.V. Sampathkumaran, R. Vijayaraghavan, Y. Nakazawa and M. Ishikawa, Physica C 173 ( 1991 ) 331; (d) Ref. [2]. [ 11 ] X.X. Tang, A. Manthiram and J.B. Goodenough, Physica C 161 (1989) 574.
Physica C 182 (1991) 153-156 North-Holland
Superconductivity in the (Dy
Ba2Cu2Oysystem
X.W. Cao, C.Y. Wu and J.C. H o Departments of Physics and Chemistry and National Institute for Aviation Research, Wichita State University, Wichita, KS 67208, USA Received 28 June 1991 Revised manuscript received 28 August 1991
A series of orthorhombic (Dyt _xPrx)Ba2Cu3Oy samples with x = 0-1.0 were synthesized and characterized by XRD, DTA and electrical resistivity measurements. Pr-doping suppresses the superconducting transitions more or less linearly to a complete quenching at x-~ 0.6. Meanwhile, increase in normal-state resistivities and their deviation from a linear temperature dependence begin to show up near x -~ 0.3-0.4, beyond which a semiconducting behavior prevails. These results are discussed in conjunction with those previously reported for isomorphic compounds (Yt _~Prx) Ba2Cu3Oy, ( Eut _xPr~) Ba2Cu3Oy, and ( Gd~ _~Pr~) Ba2Cu30 r
It has been well established that the orthorhombic structure of YBa2Cu3Ov(Y- 123) is retained when
yttrium is replaced by most of the rare earth (RE) elements excluding Ce, Tb, or Pm. The resulting
~.000 c N T S
/
v
800
s E c 600
400
~
r,~
~
(..q
20
25
30
35
40
45
50
55
60
2 THETA
Fig. 1. A typical X-ray diffraction pattern for x = 0.15, corresponding to the orthorhombic 123-structure. 0921-4534/91/$03.50 © 1991 Elsevier Science Publishers B.V. All rights reserved.
154
X. W. Cao et al. / Superconductivity in the (Dyl_xPr~)Ba2Cu30r system 0.05
x=0.3
"•
0.00-
1080-
b
o
o c o
o
o
o
o
o
x
o
o
1040
-0. o5-
0 o
(by1-xPr,)Ba2CusOy
4J
F- 1000 t-
o
Tp
Te
-0. 10-
960
o.o
-0.15
~oo
s~o
,
,
0.2
0.4
J
0.'6
9do
Tp
1.o 9go
Temperature
~obo
lo~o
1loo
(°C)
Fig. 2. A typical DTA trace for defining the extrapolated-onset (Te) and peak (Tp) temperatures of peritectic melting, with their dependence on x shown in the inset. REBa2Cu30,, (RE- 123) compounds exhibit almost identical superconducting transitions with T~> 90 K except for the case where R E = Pr [ 1 ]. Mechanisms for the absence of superconductivity in Pr-123 and a well documented depression of Tc in Y-123 by Prsubstitution [ 1,2 ] are yet to be clarified. Two mechanisms with various experimental evidence [ 2 ] have been proposed: (1) tetravalent or mixed-valent Pr-induced hole filling or localization of mobile holes in the conducting Cu20 planes [ 3 ] and (2) magnetic pair breaking through the hybridization of trivalent Pr 4f and O 2p states of CuO2 planes [4]. They also reflect the uncertainty in the valence of Pr-ions [ 5 ]. The first mechanism and the higher-valent state are further supported by the studies on superconducting (Pr.sCa.5) BazCu3Oy [ 6 ] and (Y~ ..... .vPrxCay) Ba2Cu3Oy [ 7 ]. Superconductivity is suggested to be enhanced by compensating the detrimental Pr-effect through hole doping with Ca 2÷ ions. In the magnetic pair breaking mechanism, the exchange interaction is presumably a consequence of the fact that Pr 3+ has the largest radius among all magnetic RE 3+ ions. Indeed, no appreciable coupling is observed between the occurrence of super-
conductivity and magnetic interactions among rare earth ions with larger magnetic moments in superconducting RE-123. For example, the antiferromagnetic ordering of Gd 3+ in Gd-123 remains near 2.2 K when superconductivity is quenched through oxygen deficiency [ 8 ]. To better resolve these complicated but important issues, experimental results need to be derived from more systems. Several recent articles describe the x-dependence of the superconducting behavior of (Eul_xPrx)BazCu3Oy [9] and (Gdl_xPrx)Ba2Cu3Oy [2,10], in addition to (Yl_xPrx)Ba2Cu3Oy [2]. This work deals with another mixed system, (Dy~_xPrx)Ba2Cu3Oy, involving a heavy rare earth element Dy. A series of (Dyl_xPrx)-123 samples, with x = 0 , 0.02, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0, respectively, were synthesized by solidstate reactions from high-purity Dy203, Pr60~, BaCO3, and CuO. Thoroughly mixed ingredient powders for each sample were first calcined in air at 900 °C for 12 h. The product was reground and pelletized for two consecutive sintering processes of 940°C/12 h each. Following the second sintering, the sample was slowly cooled in 3 h to 600°C for a 4 h annealing in flowing oxygen, cooled again in 2 h
X. IV. Cao et al. / Superconductivity in the (Dy~_~PrABa2Cu30~ system 24
155
120 • • • m
21 18
100-
(Y,,Prx)Ba2Cu~Oy (Ref. ll) (Eu,.xPr~)BazCu~Oy (Ref. 9) (Gdt~Pr~)Ba2Cu~Oy (.Ref.10a) (DyhPrx)Ba2Cu~Oy (This work)
1512-
E O
80@ I
9-
I E
6-
c-
3-
.
O
E ~-J
60-
x=0.90 1
x=0.80 x=0.70 x=0.60
o _
D
I
I
0
0
•
O
40-
4.0 x=0.50 x=0.40
+
oo ° o°
3.0
o
2.5
o
o
09 © 2.0
o
o
x=0.30
,,
x=0.20 x=0.10
*
x=O.O0
°°Ooo
o
o
0
O
O
O
0
0
o
O. 0
, O. 1
0.12
0.i3
÷ 0.4
0.'5
O. 6
0
+
0
1.5
++ 0
1.0
0
O
0.5
+ + + + + +
+
oOO
+ oo °
~
+ [] x. = ¢~ +
+
o
o
+o+O
+o+o
o
~A~
'~A~'~
+°i~
A~
4'0--8'0"
120
1;0
2'~0
2;0
280
T (K) Fig. 3. Temperature dependence of electrical resistivity, also showing the superconducting transitions.
100 I
(Dyl-,Pr×)Ba2Cu30y 80-
&
To~ ¢
o
To~
60 13
0
40-
o.o
o.il
o'~
o.3
O.t4
0.15
X Fig. 5. Comparison of Tom variations with Pr content in four Prs u b s t i t u t e d systems.
$~0"
0.0
0.6
X
Fig. 4. Dependence of superconducting transition temperatures onx.
•
E c~
o
:>
0
0
>-, 3.5
-X
1
to 400 °C for another 8 h annealing, and finally cooled in 3 h to room temperature. X-ray powder diffraction patterns, as typified by fig. 1, correspond to an orthorhombic structure as expected. That each sample is practically of single phase is further verified by a rather clean peritectic melting-trace from differential thermal analysis in fig. 2, which also defines the extrapolated-onset (Te) and peak (Tp) temperatures for melting. The inset of fig. 2 shows the dependence of these temperatures on Pr-doping, with a maximum near x = 0 . 4 - 0 . 5 . Four-probe electrical resistivity measurements were made in a closed-cycle refrigerator. As shown in fig. 3, the results provide information concerning the normal-state resistivities and their temperature dependence, as well as the superconducting transitions for x < 0 . 6 . The reasonably narrow transition widths are given in fig. 4 in terms of Tee for the extrapolated-onset (cf. fig. 2), Tom for the middle point, and Teo for zero resistance. The non-substituted Dy123 yields a 93 K transition as previously reported. Increase in normal-state resistivities and their deviation from a linear temperature dependence at T>_ Tc begin to show up at x-~0.3-0.4, followed by a gradual change to a semiconducting behavior. Sim-
156
X. 146 Cao et at,./Superconductivity in the (Dyz_xPG)Ba2Cu3Oysystem
ilar observations have been made in (Yj_xPrx)-123 [la] and (Gd~_xPrx)-123 [10c]. Figure 5 compares the variations of Tcm among (Yl_,Pr,.)-I23 [11] (Eul_xPrx)-123 [9], (Gd~_,Pr,)-123 [10a], and (Dy~_xPrx)-123. A complete quenching of superconductivity occurs invariably near x=0.4-0.6. The effectiveness in Tc suppression by Pr-doping, however, appears to follow inversely with the ionic radii o f Y 3+, Eu 3+, G d 3+, and D y 3+.
Acknowledgement This work was supported by Ametek, Inc. and the Kansas Technology Enterprise Corporation. The authors would like to thank Yuanji Tang for his technical assistance.
References [ l ] (a) L. Soderholm, K. Zhang, D.G. Hinks, M.A. Beno, J.D. Jorgensen, C.U. Segre and I.K. Schuller, Nature 328 (1987) 604; (b) Y. Dalichaouch, M.S. Torikachvili, E.A. Early, B.W. Lee, C.L. Seaman, K.N. Yang, H. Zhou and M.B. Maple, Solid State Commun. 65 (1988) 1001. [2] For a recent account of numerous reports see, e.g., H.D. Yang, P.F. Chen, C.R. Hsu, C.W. Lee, C.L. Li and C.C. Peng, Phys. Rev. B 43 ( 1991 ) 10568, and references therein. [ 3 ] For early studies see ref. [ 1] and J. Zaanen, A.T. Paxton, O. Jepsen and O.K. Andersen, Phys. Rev. Lett. 60 (1988) 2685.
[4] For early studies see (a) J.J. Neumeier, M.B. Maple and M.S. Torikachvili, Physica C 156 (1988) 574; (b) J.S. Kang, J.W. Allen, Z.X. Shen, W.P. Ellis, J.J. Yeh, B.W. Lee, M.B. Maple, W.E. Spicer and I. Lindau, J. Less Common Met. 148 (1989) 121; (c) A. Kebede, C.S. Jee, J. Schwegler, J.E. Crow, T. Mihalisin, G.H. Myer, R.E. Salomon, P. Schlonmann, M.V. Kuric, S.H. Bloom and R.P. Guertin, Phys. Rev. B 40 (1989) 4453; (d) J.L. Peng, P. Klavins, R.N. Shelton, H.B. Radousky, P.A. Hahn and L. Bernardez, Phys. Rev. B 40 (1989) 4517. [ 5 ] For a summary see, e.g., M.B. Maple, N.Y. Ayoub, J. Beille, T. Bjornholm, Y. Dalichaouch, E.A. Early, S. Ghamaty, B.W. Lee, J.T. Markert, J.J. Neumeier, G. Nieva, L.M. Paulius, I.K. Schuller, C.L. Seaman and P.K. Tsai, Proc. '90 Int. Conf. Transport Prop. Supercond., Rio de Janeiro, Brazil (World Scientific, Singapore, 1990) p. 536. [6] D.P. Norton, D.H. Lowndes, B.C. Sales, J.D. Budai, B.C. Chakoumakos and H.R. Kerchner, Phys. Rev. Lett. 66 (1991) 1537. [7 ] J.J. Neumeier, T. Bjornholm, M.P. Maple and I.K. Schuller, Phys. Rev. Lett. 63 (1989) 2516. [8] (a) J.C. Ho, P.H. Hor, R.L. Meng, C.W. Chu and C.Y. Huang, Solid State Commun. 63 (1987) 711; (b) J.C. Ho, C.Y. Huang, P.H. Hor, R.L. Meng and C.W. Chu, Mod. Phys. Lett. B 1 (1988) 417. [9] K. Latka, A. Szytula, Z. Tomkowicz, A. Zygmunt and R. Duraj, Physica C 171 (1990) 287. [lO] (a) H. lwasaki, Y. Dalichaouch, J.T. Markert, G. Nieva, C.L. Seaman and M.B. Maple, Physica C 169 (1990) 146; (b) Z. Tomkowicz, K. Latka, A. Szytula, A. Bajorek, M. Balanda, R. Kmiec, R. Kruk and A. Zygmunt, Physica C 174 (1991) 71; (c) 1. Das, E.V. Sampathkumaran, R. Vijayaraghavan, Y. Nakazawa and M. Ishikawa, Physica C 173 ( 1991 ) 331; (d) Ref. [2]. [ 11 ] X.X. Tang, A. Manthiram and J.B. Goodenough, Physica C 161 (1989) 574.