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LaBa2Cu3O7-y with zero resistivity at 79K
Solid State Communications,Vo1.64,No.8, pp.l133-1135, 1987. Printed in Great Britain.
0038-1098/87 $3.00 + .OO Pergamon Journals Ltd.
LaBa2cu307-yWith Zero ResistivityAt 79K Q. LP, C.Y. Li, K. Wu, and D. Yin+ (Departmentof Physics, Peking University,Beijing, China) (Received5 Aug. 1987 by W.Y.Kuan) We have observed high-Tc superconductivityin LaBa2Cu307_y with zero resistivityat 79K and onset temperature91K. Orthorhombicstructure were proposed to be existed in this compound by X-ray diffractionpattern and responsible for the Tc as high as about 9OK.
of La2o3* Ba02 and CuO. The starting
Since the initial discovery of possible high temperaturesuperconductivity
materials were heated at 8OO'C for 10
(-30K) in La-Ba-Cu-0'compounds,a large
hours and 930°C for 48 hours in air,
number of studies have been done on Ba2-
cooled slowly in the furnace, reground
2,3 and a family of rare earths ycu307-y substitution4. Most of these compounds
and pressed into pellets again. The products were sintered a second time at
show complete superconductivityTc above
960°C for 10 hours in air and 5 hours in
85K with orthorhombicoxygen defect
low vacuum, cooled very slowly in oxygen,
Itructure, neverthless,Ba2LaCu307_y5,6
and finally annealed in oxygen at 650°C
compounds were reported to have tetrago-
for 15 hours. Four terminal dc resistance measure-
nal structure and their Tc of zero resistance were lower than the boiling
ments were performed on the sample and
point of LN2. In this report, we show
the results are shown in Fig.?. It is
the first observationof superconducti-
clearly to seen that the superconducting
vity in Ba2LaCu307_ywith zero resis-
transition appears at 91K and the resis-
tivity at 79K and onset temperatureat
tivity drops to zero at 79K. Relatively
91K. X-ray powder diffractionpattern
large transitionwidth compared with Y-
suggested that orthorhombicstructure
Ba2Cu307_y propably results from a more
was existed.
inhomogeneitydue to the similar radii of La and Ba ions.
Samples investigatedwere prepared
The powder X-ray spectrum is shown
with the pressed pellets of the mixture
in Fig.2. Though the diffractionlines +Special member of the Center of Condensed Matter and Radiation, CCAST (WORLD LABORATORY) *Graduate student
and their relative intensitiesare similar to that of tetragonalBa2LaCu307_y5, however two interestingfine structures
1133
LaBa Cu 0 2 37-y
WITHZERORESISTIVITY AT 79K be
Vol.64, No. 8
attributed to other exotic phases
since when the samples were retreated in vacuum at 400C,the relative peak heights changed in the same way as oxygen dopped 7
YBa2a307_y’
I and finally the phase tran-
sition from orthorhombicto tetragonal structure was can
O4080
observed. At present we
not determine whether the specimen
is single phased orthorhombic lattice with
temperature(K)
slightly different lattice parameter
a and b or a mixture of orthorhombicand Fig.1. Resistivityvs. temperature curve
tetragonal phases, because of the overlap of these two diffractionspectrums.
for the LaBa2Cu307_y.
In comparisionwith YBa2Cu307_y,the less obvious orthorhombicityof LaBa Cu 0 2 3 7-y may be the result of lower ordering of
cu torget
La and Ba owing to the bigger radius of La atom. Compared with the results of Izumi Nakai5 as well as our former observations that Tc of LaBa2Cu3iP7_y7with tetragonal structure is around 50K, we 70
60
LO
60
30
20
26
proposed the orthorhombicoxygen defect structure was responsible for Tc as high as 9OK in LaBa2Cu307_y.
Fig.2. X-ray diffractionpattern for the LaBa2Cu303_ysample.
are pointed. We note the peaks of (ZOO)
In summary, we have made LaBa2Cu30.I-Y compounds with zero resistivity at 79K
and (026) marked by arrows are splited
and onset temperatureat 91K. The X-ray
from the original (020) and (206)
diffraction data suggest a possible
lines
seperatly, which is correspond to the
orthorhombicphase existed, and we spe-
disparity between lattice parameters a
culate that this phase is responsible
and b. The lack of distinguishablesplit
for superconductivityat about 9OK in La-
of the main peaks (013) and (103) is due
Ba2Cu307_y system. It seems there was a
to the small difference between these
stable tetragonal phase which displayed
two interplaner spacings. !J!he observed
superconductivitywith Tc around 50K.
splittings pointed out by arrows can not
Sharper transition width is expected if
Vol. 64, No. 8
LaBa Cu 0 2 3 J-y
WITH ZERO RESISTIVITY AT 79K
1135
more perfect structure could be achieved.
Acknowledgment -- We would like to thank
Further work is still undergoing in this
Prof.Z.Z.Gan,Q.Z.Wen and W.B.Zhang for
system.
helpful discussions. Reference
1. J.G.Bednorzand K.A.Muller, Z.Phys., B64, 189(1986). 2. Wen Qingzhe, Zhang Wenbin, Li Qi, Jing Qidu et al., KEXUE TONGBAO, No.7 495(1987). 3. B.Batlogg,A.P.Ramirez,R.J.Cava, R. B.Van Dover and E.A.Rietman,(preprint) 4. J.M.Tarascon,L.H.Greene,B.G.Baglcy, W.R.Mckinnon,P.Barbouxand G.W.Hull (preprint).
5. Izumi Nakai, Katsuhiro Imai, Takuji Kawashima, and Ryozo Yoshizaki, submitted to Jpn.J.Appl.Phys. 6. D.B.Mitzi, J.Z.Sun, D.J.Webb, M.R. Beasley, T.H.Geballc,and A.Kapitulnik (preprint). 7. Q.Li, Ph.D thesiscin press).
0038-1098/87 $3.00 + .OO Pergamon Journals Ltd.
LaBa2cu307-yWith Zero ResistivityAt 79K Q. LP, C.Y. Li, K. Wu, and D. Yin+ (Departmentof Physics, Peking University,Beijing, China) (Received5 Aug. 1987 by W.Y.Kuan) We have observed high-Tc superconductivityin LaBa2Cu307_y with zero resistivityat 79K and onset temperature91K. Orthorhombicstructure were proposed to be existed in this compound by X-ray diffractionpattern and responsible for the Tc as high as about 9OK.
of La2o3* Ba02 and CuO. The starting
Since the initial discovery of possible high temperaturesuperconductivity
materials were heated at 8OO'C for 10
(-30K) in La-Ba-Cu-0'compounds,a large
hours and 930°C for 48 hours in air,
number of studies have been done on Ba2-
cooled slowly in the furnace, reground
2,3 and a family of rare earths ycu307-y substitution4. Most of these compounds
and pressed into pellets again. The products were sintered a second time at
show complete superconductivityTc above
960°C for 10 hours in air and 5 hours in
85K with orthorhombicoxygen defect
low vacuum, cooled very slowly in oxygen,
Itructure, neverthless,Ba2LaCu307_y5,6
and finally annealed in oxygen at 650°C
compounds were reported to have tetrago-
for 15 hours. Four terminal dc resistance measure-
nal structure and their Tc of zero resistance were lower than the boiling
ments were performed on the sample and
point of LN2. In this report, we show
the results are shown in Fig.?. It is
the first observationof superconducti-
clearly to seen that the superconducting
vity in Ba2LaCu307_ywith zero resis-
transition appears at 91K and the resis-
tivity at 79K and onset temperatureat
tivity drops to zero at 79K. Relatively
91K. X-ray powder diffractionpattern
large transitionwidth compared with Y-
suggested that orthorhombicstructure
Ba2Cu307_y propably results from a more
was existed.
inhomogeneitydue to the similar radii of La and Ba ions.
Samples investigatedwere prepared
The powder X-ray spectrum is shown
with the pressed pellets of the mixture
in Fig.2. Though the diffractionlines +Special member of the Center of Condensed Matter and Radiation, CCAST (WORLD LABORATORY) *Graduate student
and their relative intensitiesare similar to that of tetragonalBa2LaCu307_y5, however two interestingfine structures
1133
LaBa Cu 0 2 37-y
WITHZERORESISTIVITY AT 79K be
Vol.64, No. 8
attributed to other exotic phases
since when the samples were retreated in vacuum at 400C,the relative peak heights changed in the same way as oxygen dopped 7
YBa2a307_y’
I and finally the phase tran-
sition from orthorhombicto tetragonal structure was can
O4080
observed. At present we
not determine whether the specimen
is single phased orthorhombic lattice with
temperature(K)
slightly different lattice parameter
a and b or a mixture of orthorhombicand Fig.1. Resistivityvs. temperature curve
tetragonal phases, because of the overlap of these two diffractionspectrums.
for the LaBa2Cu307_y.
In comparisionwith YBa2Cu307_y,the less obvious orthorhombicityof LaBa Cu 0 2 3 7-y may be the result of lower ordering of
cu torget
La and Ba owing to the bigger radius of La atom. Compared with the results of Izumi Nakai5 as well as our former observations that Tc of LaBa2Cu3iP7_y7with tetragonal structure is around 50K, we 70
60
LO
60
30
20
26
proposed the orthorhombicoxygen defect structure was responsible for Tc as high as 9OK in LaBa2Cu307_y.
Fig.2. X-ray diffractionpattern for the LaBa2Cu303_ysample.
are pointed. We note the peaks of (ZOO)
In summary, we have made LaBa2Cu30.I-Y compounds with zero resistivity at 79K
and (026) marked by arrows are splited
and onset temperatureat 91K. The X-ray
from the original (020) and (206)
diffraction data suggest a possible
lines
seperatly, which is correspond to the
orthorhombicphase existed, and we spe-
disparity between lattice parameters a
culate that this phase is responsible
and b. The lack of distinguishablesplit
for superconductivityat about 9OK in La-
of the main peaks (013) and (103) is due
Ba2Cu307_y system. It seems there was a
to the small difference between these
stable tetragonal phase which displayed
two interplaner spacings. !J!he observed
superconductivitywith Tc around 50K.
splittings pointed out by arrows can not
Sharper transition width is expected if
Vol. 64, No. 8
LaBa Cu 0 2 3 J-y
WITH ZERO RESISTIVITY AT 79K
1135
more perfect structure could be achieved.
Acknowledgment -- We would like to thank
Further work is still undergoing in this
Prof.Z.Z.Gan,Q.Z.Wen and W.B.Zhang for
system.
helpful discussions. Reference
1. J.G.Bednorzand K.A.Muller, Z.Phys., B64, 189(1986). 2. Wen Qingzhe, Zhang Wenbin, Li Qi, Jing Qidu et al., KEXUE TONGBAO, No.7 495(1987). 3. B.Batlogg,A.P.Ramirez,R.J.Cava, R. B.Van Dover and E.A.Rietman,(preprint) 4. J.M.Tarascon,L.H.Greene,B.G.Baglcy, W.R.Mckinnon,P.Barbouxand G.W.Hull (preprint).
5. Izumi Nakai, Katsuhiro Imai, Takuji Kawashima, and Ryozo Yoshizaki, submitted to Jpn.J.Appl.Phys. 6. D.B.Mitzi, J.Z.Sun, D.J.Webb, M.R. Beasley, T.H.Geballc,and A.Kapitulnik (preprint). 7. Q.Li, Ph.D thesiscin press).