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Phase formation and superconductivity in BiPbSrCaCuO
Physica C 162-164 (1989) 1227-1228 North-Holland
PHASE FORMATION AND SUPERCONDUCTIVITY IN Bi-Pb-Sr-Ca-Cu-O
D.KOVACHEVA+, K.PETROV+, V.LOVCHINOV++, E.NAZAROVA++, P.DOCHEV++, G.MELNIKLIEV++, V.KOVACHEV++ + I n s t i t u t e of General and Inorganic Chemistry, Bulg. Aced. Sci., 1040 Sofia, Bulgaria ++Institute of Solid State Physics, Bulg. Acad. Sci., 1784 Sofia, Bulgaria The i n f l u e n c e o f v a r i o u s c o n t e n t o f Pb++ on t h e f o r m a t i o n o f 2201, 2212 and 2223 phases a t f i x e d p r e p a r a t i o n c o n d i t i o n s has been s t u d i e d f o r Bi-Pb-Sr-Ca-Cu-O ceramics. I t has been found t h a t Pb substitutions generally lead t o r e d u c t i o n o f unreacted CuO and 2201 phase f r a c t i o n in the material. Pb h e l p s f o r b e t t e r growth o f 2212 phase as w e l l as f o r n u c l e a t i o n o f h i g h T c 2223 phase. The c r i t i c a l t e m p e r a t u r e vs t h e Pb c o n t e n t e x h i b i t s a markedly pronounced maximum.
1. INTRODUCTION
investigation
The i n t e n s i v e s t u d i e s o f Bi-Sr-Ca-Cu-O o x i d e s have shown t h e presence o f t h r e e s u p e r c o n d u c t i n g phases 1-3.
The f i r s t
one -
critical
at
reported
for
Bl-compounds 4 ' 5 known as
pointed out that
are
2223.
85-115 K
related
to
Many a u t h o r s 4 ' 5
the substitution
i n 8i-Sr-Ca-Cu-O r e s u l t s
carried
out
by
powder
difractoemter with f i l t e r e d COk~ radiation and s c i n t i l l a t i o n registration. 3. RESULTS AND DISCUSSION
about 85 K. The
t e m p e r a t u r e s i n t h e range o f
a n o t h e r phase,
been
2201 has a c r i t i c a l
t e m p e r a t u r e a t about 22 K w h i l e t h e second one2212 shows z e r o r e s i s t a n c e
has
of
Pb f o r
Bi
in i n c r e a s i n g o f s u p e r -
conducting c r i t i c a l parameters of the material.
The
2201,2212
obtained
from
influence
on
investigation
of
formation
of
the
and 2223 phases
in
Bi-Pb-Sr-Ca-Cu-O
a r e summarized in Table 1. I t
i s shown t h a t t h e
2201 samples w i t h o u t Pb have in our case T =17 c K. The Pb c o n t e n t o f x=0.1 reduces t h e T c down to
The aim of the present paper is to study the
results
Pb-content
8
K.
Continuous (up
leads
complete
to x=O.5) on the formation of above mentioned
a n a l y s e s o f these samples show presence o n l y o f
phases and t h e i r c r i t i c a l temperatures.
the
2201
charge 2. EXPERIMENTAL
reasonable
The samples were prepared from amounts o f
high purity
corresponding
raw m a t e r i a l s .
The pow-
ders were mixed and s i n t e r e d a t 800-830°C f o r hours and
in a i r . pressed
sintered
at
subsequently
The o b t a i n e d m a t e r i a l into
pellets,
830-850°C slow
phase.
and
cooled
superconducting transition
the
durlng
was ground
latter 8
6
being
hours
and
affects but
to
Since
Pb++
radius
assume
these
yanishing has
than
that
of a
BI +++,
Pb++
samples T c.
XRD
different it
is
substitution
not o n l y t h e 9eometry o f t h e BiO l a y e r s
also
violation
ion
in
Pb
concentration a
x=0.5)
of
influence of different Pb-content (from x=O.1 up
to
to
increasing
induces
charged
defects
of the electroneutrality
Both e f f e c t s
probably results
of superconductivity
in t h i s
due
to
requirements.
in t h e d e p r e s s i o n phase.
The
The T - v a l u e s o f t h e 2212 samples w i t h o u t Pb c a r e c l o s e t o t h a t p u b l i s h e d in t h e l i t e r a t u r e .
has been measured by
The XRD analyses o f t h e s e samples show presence
down t o
300
four-probe technique.The X-ray diffraction
K.
(XRD)
0921-4534/89/$03.50 © Elsevier Science Publishers B.V. (North-Holland)
m a i n l y o f 2212 phase, small anmunt o f 2201-phase
D. Kovacheva et al. / Phase formation and superconductivity in Bi-Pb-Sr-Ca-Cu-O
1228
TABLE 1 SAMPLES
T end c K
Bi2Sr2CUlOy
17
B i l . 9 P b o . 1Sr2CUlOy
2201 + CuO
8
Bll.8Pbo•2Sr2CUlOy
--
Tc end K 100
phases in the samples
2201
90
2201
Bil•7Pbo•3Sr2CUlOy
--
2201
Btl•6Pb0.4Sr2CUlOy
--
2201
Bll•5Pbo.5Sr2CUlO Y
--
2201
BI2Sr2CaCU2Oy
87
30% 2201+65~ 2212 +5~ CuO
Bi 1 9Pbo 1Sr2CaCU2Oy
72
20~ 2201+75¢ 2212 CuO
Bll".8Pb0.2Sr2CaCU2Oy
80
10~ 2201+90t 2212
Bll.7Pbo.3Sr2CaCU2Oy
62
2212
Bil.6Pbo.4Sr2CaCU2Oy
75
2212
Bll.5Pbo.5Sr2CeCu2Oy
79
Bi2Sr2Ca2CU3Oy
79
•
•
801
+ 5 ~
FIGURE 1
2212 + CuO 20t 2201+70t 2212 +10~ CuO
76
20~ 2201+80~ 2212
Bil.8Pb0.2Sr2CaCU2Oy
74
15~ 2201+85~ 2212
Bil.7Pbo.3Sr2CeCU2Oy
80
IOZ 2201+90t 2212
811 6Pbo 4Sr2CaCU2Oy
92
10~ 2201+80~ 2212 +10~ 2223 IOZ 2201~90~ 2212
"
Bil.5Pbo.5Sr2Ca2Cu3Oy
73
,
o,1
Dependence o f Tcend on the concentracion o f Pb f o r 2223 m a t e r i a l .
Bll.9Pbo.1Sr2Ca2CU3Oy
•
70
measurements
samples
although
the
XRD data
decreasing t o complete v a n i s h i n g o f
c mark
i s due t o Bi replacement by Pb in s p i t e structural For
temperature
for
materials
At
experimental
conditions
used
the
Bi
by Pb leads t o :
-depression
of
superconductivity
in
2201
phase -stabilization
of
2212 phase w i t h
some not
r e g u l a r r e d u c t i o n o f Tc•
o f no
-maximum Tc f o r Bil.6Pb0.4Sr2Ca2CU3Oy•
symmetry change.
the
third
stoichlometrlc
has
sample been
series,
used.
2:2:2:3
However,
-phase
existence.
Substituting
REFERENCES
for
samples w i t h o u t Pb XRD data g l v e o n l y 2212 and 2201
a
4. CONCLUSIONS
2201 phase
f o r samples w i t h Pb • Decreasing o f Tc probably
give
investigated.
substitution these
Bi I ~Pb0 4Sr2Ca2Cu30
maximum c r i t i c a l
and t r a c e s o f CuO• The Pb-content decreases T of
for
l a r g e r value o f c=36.2"A a~d as mentioned above
1. J.Q. L i , C• Chen e t e l • , 165.
Z• Phys. B 74 (1989)
different
amounts o f Bt2_ x by Pbx up t o x=0•4 we observed
2. C. Michel, B. Hervien e t e l . , (1987) 421.
Z• Phys. B 68
a decrease o f the content o f 2201 phase. At t h i s Pb c o n c e n t r a t i o n T Pb c o n t e n t f o r in F l g • l . content
i s maximum• T dependence vs c c samples o f 2223 s e r i e s i s shown
The XRO data f o r samples w i t h x=O•4 Pb
3. H• Maeda, Y• Tanaka, M. Fukutomi and T. Asano Jap• J• Appl. Phys. L e t t • 27 (1988) L209• 4.
K• Togano, H• Kumakura e t L e t t • 53 (1988) 1329.
al.,
Appl•
Phys.
show beside 2201 and 2212-phases a l s o
existence of
2223-phase.
The l a t t i c e
parameter
5• A• Ono, K• Kosuda, S. Sueno, Y• Ishizawa, Jap. J. Appl• Phys. L e t t . 27 (1988) L1007•
PHASE FORMATION AND SUPERCONDUCTIVITY IN Bi-Pb-Sr-Ca-Cu-O
D.KOVACHEVA+, K.PETROV+, V.LOVCHINOV++, E.NAZAROVA++, P.DOCHEV++, G.MELNIKLIEV++, V.KOVACHEV++ + I n s t i t u t e of General and Inorganic Chemistry, Bulg. Aced. Sci., 1040 Sofia, Bulgaria ++Institute of Solid State Physics, Bulg. Acad. Sci., 1784 Sofia, Bulgaria The i n f l u e n c e o f v a r i o u s c o n t e n t o f Pb++ on t h e f o r m a t i o n o f 2201, 2212 and 2223 phases a t f i x e d p r e p a r a t i o n c o n d i t i o n s has been s t u d i e d f o r Bi-Pb-Sr-Ca-Cu-O ceramics. I t has been found t h a t Pb substitutions generally lead t o r e d u c t i o n o f unreacted CuO and 2201 phase f r a c t i o n in the material. Pb h e l p s f o r b e t t e r growth o f 2212 phase as w e l l as f o r n u c l e a t i o n o f h i g h T c 2223 phase. The c r i t i c a l t e m p e r a t u r e vs t h e Pb c o n t e n t e x h i b i t s a markedly pronounced maximum.
1. INTRODUCTION
investigation
The i n t e n s i v e s t u d i e s o f Bi-Sr-Ca-Cu-O o x i d e s have shown t h e presence o f t h r e e s u p e r c o n d u c t i n g phases 1-3.
The f i r s t
one -
critical
at
reported
for
Bl-compounds 4 ' 5 known as
pointed out that
are
2223.
85-115 K
related
to
Many a u t h o r s 4 ' 5
the substitution
i n 8i-Sr-Ca-Cu-O r e s u l t s
carried
out
by
powder
difractoemter with f i l t e r e d COk~ radiation and s c i n t i l l a t i o n registration. 3. RESULTS AND DISCUSSION
about 85 K. The
t e m p e r a t u r e s i n t h e range o f
a n o t h e r phase,
been
2201 has a c r i t i c a l
t e m p e r a t u r e a t about 22 K w h i l e t h e second one2212 shows z e r o r e s i s t a n c e
has
of
Pb f o r
Bi
in i n c r e a s i n g o f s u p e r -
conducting c r i t i c a l parameters of the material.
The
2201,2212
obtained
from
influence
on
investigation
of
formation
of
the
and 2223 phases
in
Bi-Pb-Sr-Ca-Cu-O
a r e summarized in Table 1. I t
i s shown t h a t t h e
2201 samples w i t h o u t Pb have in our case T =17 c K. The Pb c o n t e n t o f x=0.1 reduces t h e T c down to
The aim of the present paper is to study the
results
Pb-content
8
K.
Continuous (up
leads
complete
to x=O.5) on the formation of above mentioned
a n a l y s e s o f these samples show presence o n l y o f
phases and t h e i r c r i t i c a l temperatures.
the
2201
charge 2. EXPERIMENTAL
reasonable
The samples were prepared from amounts o f
high purity
corresponding
raw m a t e r i a l s .
The pow-
ders were mixed and s i n t e r e d a t 800-830°C f o r hours and
in a i r . pressed
sintered
at
subsequently
The o b t a i n e d m a t e r i a l into
pellets,
830-850°C slow
phase.
and
cooled
superconducting transition
the
durlng
was ground
latter 8
6
being
hours
and
affects but
to
Since
Pb++
radius
assume
these
yanishing has
than
that
of a
BI +++,
Pb++
samples T c.
XRD
different it
is
substitution
not o n l y t h e 9eometry o f t h e BiO l a y e r s
also
violation
ion
in
Pb
concentration a
x=0.5)
of
influence of different Pb-content (from x=O.1 up
to
to
increasing
induces
charged
defects
of the electroneutrality
Both e f f e c t s
probably results
of superconductivity
in t h i s
due
to
requirements.
in t h e d e p r e s s i o n phase.
The
The T - v a l u e s o f t h e 2212 samples w i t h o u t Pb c a r e c l o s e t o t h a t p u b l i s h e d in t h e l i t e r a t u r e .
has been measured by
The XRD analyses o f t h e s e samples show presence
down t o
300
four-probe technique.The X-ray diffraction
K.
(XRD)
0921-4534/89/$03.50 © Elsevier Science Publishers B.V. (North-Holland)
m a i n l y o f 2212 phase, small anmunt o f 2201-phase
D. Kovacheva et al. / Phase formation and superconductivity in Bi-Pb-Sr-Ca-Cu-O
1228
TABLE 1 SAMPLES
T end c K
Bi2Sr2CUlOy
17
B i l . 9 P b o . 1Sr2CUlOy
2201 + CuO
8
Bll.8Pbo•2Sr2CUlOy
--
Tc end K 100
phases in the samples
2201
90
2201
Bil•7Pbo•3Sr2CUlOy
--
2201
Btl•6Pb0.4Sr2CUlOy
--
2201
Bll•5Pbo.5Sr2CUlO Y
--
2201
BI2Sr2CaCU2Oy
87
30% 2201+65~ 2212 +5~ CuO
Bi 1 9Pbo 1Sr2CaCU2Oy
72
20~ 2201+75¢ 2212 CuO
Bll".8Pb0.2Sr2CaCU2Oy
80
10~ 2201+90t 2212
Bll.7Pbo.3Sr2CaCU2Oy
62
2212
Bil.6Pbo.4Sr2CaCU2Oy
75
2212
Bll.5Pbo.5Sr2CeCu2Oy
79
Bi2Sr2Ca2CU3Oy
79
•
•
801
+ 5 ~
FIGURE 1
2212 + CuO 20t 2201+70t 2212 +10~ CuO
76
20~ 2201+80~ 2212
Bil.8Pb0.2Sr2CaCU2Oy
74
15~ 2201+85~ 2212
Bil.7Pbo.3Sr2CeCU2Oy
80
IOZ 2201+90t 2212
811 6Pbo 4Sr2CaCU2Oy
92
10~ 2201+80~ 2212 +10~ 2223 IOZ 2201~90~ 2212
"
Bil.5Pbo.5Sr2Ca2Cu3Oy
73
,
o,1
Dependence o f Tcend on the concentracion o f Pb f o r 2223 m a t e r i a l .
Bll.9Pbo.1Sr2Ca2CU3Oy
•
70
measurements
samples
although
the
XRD data
decreasing t o complete v a n i s h i n g o f
c mark
i s due t o Bi replacement by Pb in s p i t e structural For
temperature
for
materials
At
experimental
conditions
used
the
Bi
by Pb leads t o :
-depression
of
superconductivity
in
2201
phase -stabilization
of
2212 phase w i t h
some not
r e g u l a r r e d u c t i o n o f Tc•
o f no
-maximum Tc f o r Bil.6Pb0.4Sr2Ca2CU3Oy•
symmetry change.
the
third
stoichlometrlc
has
sample been
series,
used.
2:2:2:3
However,
-phase
existence.
Substituting
REFERENCES
for
samples w i t h o u t Pb XRD data g l v e o n l y 2212 and 2201
a
4. CONCLUSIONS
2201 phase
f o r samples w i t h Pb • Decreasing o f Tc probably
give
investigated.
substitution these
Bi I ~Pb0 4Sr2Ca2Cu30
maximum c r i t i c a l
and t r a c e s o f CuO• The Pb-content decreases T of
for
l a r g e r value o f c=36.2"A a~d as mentioned above
1. J.Q. L i , C• Chen e t e l • , 165.
Z• Phys. B 74 (1989)
different
amounts o f Bt2_ x by Pbx up t o x=0•4 we observed
2. C. Michel, B. Hervien e t e l . , (1987) 421.
Z• Phys. B 68
a decrease o f the content o f 2201 phase. At t h i s Pb c o n c e n t r a t i o n T Pb c o n t e n t f o r in F l g • l . content
i s maximum• T dependence vs c c samples o f 2223 s e r i e s i s shown
The XRO data f o r samples w i t h x=O•4 Pb
3. H• Maeda, Y• Tanaka, M. Fukutomi and T. Asano Jap• J• Appl. Phys. L e t t • 27 (1988) L209• 4.
K• Togano, H• Kumakura e t L e t t • 53 (1988) 1329.
al.,
Appl•
Phys.
show beside 2201 and 2212-phases a l s o
existence of
2223-phase.
The l a t t i c e
parameter
5• A• Ono, K• Kosuda, S. Sueno, Y• Ishizawa, Jap. J. Appl• Phys. L e t t . 27 (1988) L1007•