- Email: [email protected]
Superconducting, structural and electronic properties of R-Ba-Cu-O (R=Y, Ho,)
Physica C 153 155 (1988) 1040-1041 North-Holland, Amsterdam
SUPERCONDUCTING,
STRUCTURAL AND ELECTRONIC PROPERTIES OF R - B a - C u - O
(R=Y,Ho,
. H.R.KHAN Forschungsinstitut
f.
Edelmetalle
u.
Metallchemie,
Schwaebisch
Gmuend,
FRG
Homogenous oxides of the compositions Y B a 9 C u q O 7 , Ho n 5Yn ~ B a 2 C u q O 7 a n d HoBagCu~O7 are synthesized and character?ze~ by X-r~ dY~Yracti6n, scanning J elecgron microscopy and energy dispersive X-ray analysis. They have an orthorhomhie structure and are homogenous. The T (onset) of these oxides is 98K d e t e r m i n e d from the a.c. susceptibility measurements.D.C, magnetic susceptibility measurement is used to determine the.effective magnetic moment (~ff) and Cuie-Weiss temperature. T h e ~ ^ e f o f Ho +° i s 1 0 . 4 u B i n b o t h o x i d e s whereas the O decreases from 12 t o 7 K w t h ~ e decrease o f Ho c o n c e n t r a t i o n . The negative values of the O o f Ho c o n t a i n i n g oxides indicates the antiferromagnetic ordering at low temp P erature and the strength of the interaction a m o n g t h e Ho i o n s d e c r e a s e s with the decrease o f Ho c o n c e n t r a t i o n . 1.INTRODUCTION The substitution of Y with the rare earth trivalent ions in high T oxide does not affect T(Cl) whereas t~e substitution of ~u with other transition metal elements l o w e r s t h e T^ a p p r e c i a b l y ( 2 ) . The magnetic properties of the R.E.BagCu ~ O~ suggest a possibly antiferromRg -~ net ic ordering at low temperatures a n d 2D n a t u r e of superconductivity(3, 4). The synthesis of three oxides R B a ^ C u ~ O _ f R= Y, Ho, Ho ~Yo ~) o f ort~or~om{i~ structure ang"~ombgenous as checked by X-ray diffraction, SEM a n d EDX, s u p e r c o n d u c t i n g and magnetic properties are reported in this paper.
YBa2Cu30~.
2.EXPERIMENTAL DETAILS Three samples of compositions RBa^Cu^ O~7( R= Y, Ho, Ho 0 5Y0 ~) w e r e p r e p ~ r e ~ by high temperatur6 Slfitering technique. Well mixed powders of Y20~, BaCo. and CuO w e r e r e a c t e d at 980 (0C) in ~ir for a period o f 24 h a n d a f t e r grinding were pressed in the form of small buttons. These buttons were further annealed a t 9 8 0 ( 0 C ) f o r 20 h a n d 5 0 0 ( 0 C ) f o r 20 h i n a i r a n d s l o w l y c o o l e d to room temperature. The lattice structure at room temperature was investigated by X-ray diffraction. The investigation of the microstructure and the relative chemical analysis of the grain surface and grain boundaries was made using scanning electron microscopy and energy dispersive X-ray analysis (EDX). * Also at Knoxville,
the Department of Physics Tennessee, U.S.A.
0921-4534/88/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
The superconducting transition temperature was measured inductively using an A.C. bridge technique operating at a frequency of 18kHz. Temperature dependent D.C. magnetic susceptibility was measured by Faraday technique in a magnetic field upto 1Tesla. 3.
RESULTS AND D I S C U S S I O N The room temperature X-ray powder diffraction patterns of these oxides show that they are of orthorhombic structure for example the Fig.1 shows the X-ray diffraction pattern o f YBa2Cu 3 ON 7. T h e ~, ( a . c . ) versus temperature plots for three oxides are shown in Fig. 2. The variation o f 'X ( a . c . ) between between T and 200 K is diffrent for the t h r e e o x i d e s . The T ( o n s e t ) and T (mid) C are 98K and 92K r e s p e c t i v e l y for ~hese oxides. The t e m p e r a t u r e dependent mass magnetic s u s c e p t i b i l i t y ~, for the Ho oxides is shown in F i g . 3 . The Curie-Weiss p l o t s a f t e r c o r r e c t i n g for the t e m p e r a t u r e independent magnetic s u s c e p t i b i l i t y are a l s o shown in the same f i g u r e . The e f f e c t i v e magnetic moment ,u f r of the Ho • e I ion and t h e Curie-Weiss t e m p e r a t u r e are determined from t h e s e p l o t s and are l i s t e d in Table I. There is almost 50% r e d u c t i o n of room t e m p e r a t u r e mass magnetic s u s c e p t i b i l i t y ( R.T. ~(, ) when 50% of Y is r e p l a c e d by Ho . The C u r i e Weiss t e m p e r a t u r e ((9_) d e c r e a s e s from 12 to 7K and the e f f e c t i v e magnetic m o m e n t o f t h e Ho i o n i s s a m e e . g . 1 0 . 4 fib
and Astronomy,
University
of
Tennessee,
H.R. Khan / Properties of R - B a - C u - O (R = Y,Ho) in b o t h Ho c o n t a i n i n g oxides. The negative values of the Curie-Weiss temp erature indicate the co-existance of the antiferromagnetic ordering and s u p e r conductivity a t low t e m p e r a t u r e s . The strength of interaction among t h e Ho ions doesnot affect the superconductivity and i t d e c r e a s e s with the decrease o f Ho c o n c e n t r a t i o n . In general the Curie-Weiss temperature is close to the Neel temperature. But for unknown r e a s o n s , the Neel temperature in Ho c o n t a i n i n g high T superconductor C sofar has not been observed.
1041
1,0-
1-YBa2Eu30{7_,)(768 3)
3
3
-BO~2Eu~0CT_z~ 1753)
T(K)
FIGURE 2
~I
z 2D
YBe2cu30(7- z)(76B) 30C
,.,-;
__ --
r'¢ >-
HoBa2Cu30(7_,)(753) HoQsYQ5BQ2C u30(7_,)( 755)
165
~20C
110
31oc
55
rnl
Z
z
;,
~
un ,zX~
38
/+6
__~
5#
c-4 - -
62
50
70
20(DEG)
100
150 200 T(K)
250
300
F I GLIRE 3
REFERENCES F I GUI,'E 1 (1) TABLE 1 .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
(2) Oxide .
.
.
.
.
.
.
R.T.X .
.
.
.
.
.
.
.
.
.
YBa2Cu30~7
#elf
O
.
(3) .
.
.
.
.
.
.
.
H°Ba2Cu30~7
59
10.4
-12
H°0.5Y0.sBa2Cu30~7
32
10.4
-7
(4)
P . H . H o r , R . L . M e n g , Y . Q . Y a n g , L. Gao, Z.J. Huang, J. Bechtold, K. Forster and C.W. C h u , P h y s . R e v . L e t t 58(1987) 1891. G. X i a o , F . H . S t r e i t z , A. G a v r i n , Y.W. Du and L . L . C h e i n , P h y s . R e v . B 35(1987) 8782. Fumihiko,Nakamura, Akira Tominaga and Y o s h i m a s a N a r a h a r a , Japn. J.of Appl. Phys.Vol.26,No.10(1987) L1734 -L1735. Seiichi Kagoshima, Kei-ichi Koga, Hiroshi Yasuoka, Yoshio Nogami, K o i c h i Kubo and S h i n o b i H i k a m i , Japn. J. of Appl. Phys. Vo.26,No.4 (1987) L355- L357.
SUPERCONDUCTING,
STRUCTURAL AND ELECTRONIC PROPERTIES OF R - B a - C u - O
(R=Y,Ho,
. H.R.KHAN Forschungsinstitut
f.
Edelmetalle
u.
Metallchemie,
Schwaebisch
Gmuend,
FRG
Homogenous oxides of the compositions Y B a 9 C u q O 7 , Ho n 5Yn ~ B a 2 C u q O 7 a n d HoBagCu~O7 are synthesized and character?ze~ by X-r~ dY~Yracti6n, scanning J elecgron microscopy and energy dispersive X-ray analysis. They have an orthorhomhie structure and are homogenous. The T (onset) of these oxides is 98K d e t e r m i n e d from the a.c. susceptibility measurements.D.C, magnetic susceptibility measurement is used to determine the.effective magnetic moment (~ff) and Cuie-Weiss temperature. T h e ~ ^ e f o f Ho +° i s 1 0 . 4 u B i n b o t h o x i d e s whereas the O decreases from 12 t o 7 K w t h ~ e decrease o f Ho c o n c e n t r a t i o n . The negative values of the O o f Ho c o n t a i n i n g oxides indicates the antiferromagnetic ordering at low temp P erature and the strength of the interaction a m o n g t h e Ho i o n s d e c r e a s e s with the decrease o f Ho c o n c e n t r a t i o n . 1.INTRODUCTION The substitution of Y with the rare earth trivalent ions in high T oxide does not affect T(Cl) whereas t~e substitution of ~u with other transition metal elements l o w e r s t h e T^ a p p r e c i a b l y ( 2 ) . The magnetic properties of the R.E.BagCu ~ O~ suggest a possibly antiferromRg -~ net ic ordering at low temperatures a n d 2D n a t u r e of superconductivity(3, 4). The synthesis of three oxides R B a ^ C u ~ O _ f R= Y, Ho, Ho ~Yo ~) o f ort~or~om{i~ structure ang"~ombgenous as checked by X-ray diffraction, SEM a n d EDX, s u p e r c o n d u c t i n g and magnetic properties are reported in this paper.
YBa2Cu30~.
2.EXPERIMENTAL DETAILS Three samples of compositions RBa^Cu^ O~7( R= Y, Ho, Ho 0 5Y0 ~) w e r e p r e p ~ r e ~ by high temperatur6 Slfitering technique. Well mixed powders of Y20~, BaCo. and CuO w e r e r e a c t e d at 980 (0C) in ~ir for a period o f 24 h a n d a f t e r grinding were pressed in the form of small buttons. These buttons were further annealed a t 9 8 0 ( 0 C ) f o r 20 h a n d 5 0 0 ( 0 C ) f o r 20 h i n a i r a n d s l o w l y c o o l e d to room temperature. The lattice structure at room temperature was investigated by X-ray diffraction. The investigation of the microstructure and the relative chemical analysis of the grain surface and grain boundaries was made using scanning electron microscopy and energy dispersive X-ray analysis (EDX). * Also at Knoxville,
the Department of Physics Tennessee, U.S.A.
0921-4534/88/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
The superconducting transition temperature was measured inductively using an A.C. bridge technique operating at a frequency of 18kHz. Temperature dependent D.C. magnetic susceptibility was measured by Faraday technique in a magnetic field upto 1Tesla. 3.
RESULTS AND D I S C U S S I O N The room temperature X-ray powder diffraction patterns of these oxides show that they are of orthorhombic structure for example the Fig.1 shows the X-ray diffraction pattern o f YBa2Cu 3 ON 7. T h e ~, ( a . c . ) versus temperature plots for three oxides are shown in Fig. 2. The variation o f 'X ( a . c . ) between between T and 200 K is diffrent for the t h r e e o x i d e s . The T ( o n s e t ) and T (mid) C are 98K and 92K r e s p e c t i v e l y for ~hese oxides. The t e m p e r a t u r e dependent mass magnetic s u s c e p t i b i l i t y ~, for the Ho oxides is shown in F i g . 3 . The Curie-Weiss p l o t s a f t e r c o r r e c t i n g for the t e m p e r a t u r e independent magnetic s u s c e p t i b i l i t y are a l s o shown in the same f i g u r e . The e f f e c t i v e magnetic moment ,u f r of the Ho • e I ion and t h e Curie-Weiss t e m p e r a t u r e are determined from t h e s e p l o t s and are l i s t e d in Table I. There is almost 50% r e d u c t i o n of room t e m p e r a t u r e mass magnetic s u s c e p t i b i l i t y ( R.T. ~(, ) when 50% of Y is r e p l a c e d by Ho . The C u r i e Weiss t e m p e r a t u r e ((9_) d e c r e a s e s from 12 to 7K and the e f f e c t i v e magnetic m o m e n t o f t h e Ho i o n i s s a m e e . g . 1 0 . 4 fib
and Astronomy,
University
of
Tennessee,
H.R. Khan / Properties of R - B a - C u - O (R = Y,Ho) in b o t h Ho c o n t a i n i n g oxides. The negative values of the Curie-Weiss temp erature indicate the co-existance of the antiferromagnetic ordering and s u p e r conductivity a t low t e m p e r a t u r e s . The strength of interaction among t h e Ho ions doesnot affect the superconductivity and i t d e c r e a s e s with the decrease o f Ho c o n c e n t r a t i o n . In general the Curie-Weiss temperature is close to the Neel temperature. But for unknown r e a s o n s , the Neel temperature in Ho c o n t a i n i n g high T superconductor C sofar has not been observed.
1041
1,0-
1-YBa2Eu30{7_,)(768 3)
3
3
-BO~2Eu~0CT_z~ 1753)
T(K)
FIGURE 2
~I
z 2D
YBe2cu30(7- z)(76B) 30C
,.,-;
__ --
r'¢ >-
HoBa2Cu30(7_,)(753) HoQsYQ5BQ2C u30(7_,)( 755)
165
~20C
110
31oc
55
rnl
Z
z
;,
~
un ,zX~
38
/+6
__~
5#
c-4 - -
62
50
70
20(DEG)
100
150 200 T(K)
250
300
F I GLIRE 3
REFERENCES F I GUI,'E 1 (1) TABLE 1 .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
(2) Oxide .
.
.
.
.
.
.
R.T.X .
.
.
.
.
.
.
.
.
.
YBa2Cu30~7
#elf
O
.
(3) .
.
.
.
.
.
.
.
H°Ba2Cu30~7
59
10.4
-12
H°0.5Y0.sBa2Cu30~7
32
10.4
-7
(4)
P . H . H o r , R . L . M e n g , Y . Q . Y a n g , L. Gao, Z.J. Huang, J. Bechtold, K. Forster and C.W. C h u , P h y s . R e v . L e t t 58(1987) 1891. G. X i a o , F . H . S t r e i t z , A. G a v r i n , Y.W. Du and L . L . C h e i n , P h y s . R e v . B 35(1987) 8782. Fumihiko,Nakamura, Akira Tominaga and Y o s h i m a s a N a r a h a r a , Japn. J.of Appl. Phys.Vol.26,No.10(1987) L1734 -L1735. Seiichi Kagoshima, Kei-ichi Koga, Hiroshi Yasuoka, Yoshio Nogami, K o i c h i Kubo and S h i n o b i H i k a m i , Japn. J. of Appl. Phys. Vo.26,No.4 (1987) L355- L357.