- Email: [email protected]
Effects of preparation condition on structure and superconductivity in the LaBCO system
June 1999
Materials Letters 39 Ž1999. 305–309 www.elsevier.comrlocatermatlet
Effects of preparation condition on structure and superconductivity in the LaBCO system F. Tao
a,b,)
, G.C. Che a , X.J. Zhou c , Z. Zhao a , C. Dong a , S.L. Jia a , H. Chen b
a
a Chinese Academy of Sciences, Beijing, 100080, China Department of Materials Science, Sichuan UniÕersity, Chengdu, 610064, China c Yuzhou UniÕersity, Chongqing, 400000, China
Received 28 September 1998; accepted 18 December 1998
Abstract The effects of preparation condition on structure and superconductivity of LaBa 2 Cu 3 O y ŽLaBCO. system have been investigated, and the optimum preparation condition and superconductivity of Tc Ž0. s 97 K and Tc Žonset. s 101 K, which are the best results at present, have been achieved. The optimum preparation condition is A-B-C3-D-E. Investigations show that keeping LaBa 2 Cu 3 O y , being of tetragonal structure before oxygenation, at 3058C is a key procedure to obtain a single phase LaBa 2 Cu 3 Oy sample with the best superconductivity. q 1999 Published by Elsevier Science B.V. All rights reserved. Keywords: LaBa 2 Cu 3 O y ; Preparation condition; Structure; Superconductivity
1. Introduction Murphy et al. w1x and Hor et al. w2x first prepared LaBa 2 Cu 3 O y superconductors with Tc Ž0. greatly lower than 90 K in 1987. Much progress has been made to enhance its Tc for the past 10 years w3– 9,10a,10b,11–18x. Lindemer et al. obtained the best result with Tc Ž0. s 93 K in 1994 w18x. However, Tallon et al. w19–21x predicted that a superconducting transition temperature of 100 K should be achievable for LaBa 2 Cu 3 O y . Moreover, all the former investigators only investigated the effect of preparation condition on superconductivity, but have not investigated the effects of sample structure on superconductivity. In order to obtain and understand the optimum preparation condition and prepare high-quality single )
Corresponding author. E-mail: [email protected]
phase LaBa 2 Cu 3 O y superconductor with higher Tc , and try to prove Tallon’s prediction, this work investigated the preparation condition, structure, superconductivity and the effect of structure on superconductivity of LaBCO.
Fig. 1. The preparation condition of LaBa 2 Cu 3 O y .
00167-577Xr99r$ - see front matter q 1999 Published by Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 5 7 7 X Ž 9 9 . 0 0 0 2 5 - 7
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F. Tao et al.r Materials Letters 39 (1999) 305–309
Fig. 2. The XRD patterns of LaBa 2 Cu 3 O y prepared by different preparation conditions.
F. Tao et al.r Materials Letters 39 (1999) 305–309
2. Experimental High-purity Ž99.99%. La 2 O 3 , BaCO 3 and CuO were used to prepare LaBa 2 Cu 3 O y samples. The La 2 O 3 powder was calcinated at 9508C for 20 h in air in order to eliminate absorbed or chemically bound products. The weighed, mixed, ground starting materials were calcinated at 8008C for 8 h and 8508C for 10 h, respectively. The ground powder was pressed into pellets, placed in an Al 2 O 3 boat and prepared by different preparation condition as shown in Fig. 1. The XRD diffraction of all samples were executed with a MXP18A-HF type diffractometer with CuK a radiation. The positions of reflections were calibrated using Si powder as internal standard. Lattice parameters were calculated with Finax and Lazy programmes. The samples were analyzed for
307
superconductivity using an ac magnetometer and standard four-probe technique.
3. Results and discussion XRD patterns show that the product calcinated at 8008C for 8 h and 8508C for 10 h is a multi-phase sample. Fig. 2c–b show that samples prepared by A-B-C1-C1X or A-B-C2-C2X are of an orthorhombic structure and contain the second phase BaCuO 2 represented with asterisk. Fig. 2a shows sample prepared by A-B-C3-C3X is a single phase sample with tetragonal structure. Fig. 2c, b and a also show the contents of BaCuO 2 in samples increase with the increase of partial pressure of oxygen used as prepa-
Fig. 3. Susceptibility and RrRŽ285 K. vs. temperature for LaBa 2 Cu 3 O y prepared by A-B-C3-D-E, A-B-C2-D-E and A-B-C1-D-E preparation conditions, respectively. v: by A-B-C3-D-E, ': by A-B-C2-D-E, l: A-B-C1-D-E.
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F. Tao et al.r Materials Letters 39 (1999) 305–309
ration atmosphere wC1-C1X ŽO 2 . ) C2–C2X Žair. ) C3–C3X ŽN2 .x, and the structures of samples gradually change from orthorhombicity into tetragonal structure with the decrease of partial pressure of oxygen. So, in order to obtain single phase sample with tetragonal structure, it is necessary to execute Žc. procedure in N2 ŽC3-C3X .. Tc Ž0. of samples prepared by A-B-C1-C1X and A-B-C2-C2X is 54 and 52 K, respectively. The sample prepared by A-B-C3-C3X is nonsuperconducting which is in agreement with its tetragonal structure, nonsuperconducting phase. Fig. 2cX and bX show that samples prepared by A-B-C1-C-D-E and A-B-C2-D-E are of an orthorhombic structure and contain the second phase BaCuO 2 . Fig. 2aX shows that sample prepared by A-B-C3-D-E is single phase with orthorhombic structure. It can be seen from Fig. 2a and aX that sample prepared by A-B-C3-C3X-D-E obviously change from tetragonal into orthorhombic structure after oxygenation at 3058C for 60 h ŽD procedure., which can also be seen directly from the change of intensities of Ž020. and Ž200. reflection peaks. However, the structure of samples prepared by A-B-C1C1X and A-B-C2-C2X have not obviously changed after oxygenation at 3058C for 60 h. The sample prepared by A-B-C1-D or A-B-C2-D is a multi-phase sample which contains the second phase BaCuO 2 . It is concluded from Fig. 2aX , bX and cX that it is necessary to execute c procedure in N2 ŽC3. for obtaining a single phase LaBa 2 Cu 3 O y sample after oxygenation at 3058C for 60 h. Fig. 3 shows that Tc Ž0. and Tc Žonset. of sample prepared by A-B-C3-D-E is 97 K and 101 K, respectively, and the Tc Ž0. of samples prepared by A-B-C1D-E and A-B-C2-D-E are 91.5 and 93.5, respectively. The orthorhombic splitting factor ŽOS. in the unit cell defined with the formula, OS s 1000Ž b y a.rŽ b q a., where a and b represent the lattice parameters of unit cell, is often used to describe the orthorhombicity of RE-123 unit cell. Here it is used to describe the orthorhombicity of LaBa 2 Cu 3 O y unit cell in different preparation conditions. The OS factors of the samples prepared by A-B2C3-D-E, A-B-C2-D-E and A-B-C1-D-E conditions are 9.6, 5.4 and 5.0, respectively. This indicates that the LaBa 2 Cu 3 O y sample with largest OS factor pre-
pared by A-B2-C3-D-E condition have the best superconductivity. It was confirmed by superconductivity results.
4. Conclusions All theses investigations show that the optimum preparation condition is A-B-C3-D-E, and Žc. procedure executed in N2 is a key procedure to prepare single phase LaBa 2 Cu 3 O y superconductors with the best superconductivity. With the optimum condition, single phase LaBa 2 Cu 3 O y superconductors with Tc Ž0. s 97 K and Tc Žonset. s 101 K, which are the best results at present, was prepared. Moreover, investigation shows that Tc Ž0. of sample after oxygenation in O 2 at 3058C for 60 h is much lower than 97 K if sample has formed orthorhombic structure before executing oxygenation procedure.
References w1x D.W. Murphy, S.S. Unshine, R.B. Van Dover, R.J. Cava, B. Batlog, S.M. Zahurak, Phys. Rev. Lett. 58 Ž1988. 1888. w2x P.H. Hor, R.L. Meng, Y.Q. Wang, L. Gao, Z.J. Huang, J. Bechtold, K. Forster, C.W. Chu, Phys. Rev. Lett. 58 Ž1987. 1891. w3x T.B. Lindemer, B.C. Chakoumakos, E.D. Specht, R.K. Williams, Y.J. Chen, Physica C 231 Ž1994. 80. w4x T. Wada, H. Yamauchi, S. Tanaka, J. Am. Ceram. Soc. 75 Ž1992. 1705. w5x A. Maeda, T. Noda, H. Matsumoto, T. Wada, M. Izumi, T. Yabe, K. Uchinokura, S. Tanaka, J. Appl. Phys. 64 Ž1988. 4095. w6x T. Wada, N. Suzuhi, T. Maeda, A. Maeda, S. Uchida, K. Uchinokora, S. Tanaka, Appl. Phys. Lett. 52 Ž1988. 1989. w7x T. Wada, N. Suzuki, H. Yamauchi, S. Tanaka, A. Maeda, K. Uchiniokura, J. Am. Ceram. Soc. 72 Ž1989. 2000. w8x T. Wada, N. Suzuki, A. Waeda, T. Yabe, K. Uchinokura, S. Uchida, S. Tanaka, Phys. Rev. B 40 Ž1989. 9126. w9x M. Izumi, T. Yabe, T. Wada, A. Maeda, K. Uchinokura, S. Tanaka, H. Asano, Phys. Rev. B 40 Ž1989. 6771. w10ax S.A. Sunshine, L.F. Schneemeyer, J.V. Waszczck, D.W. Murphy, S. Miraglia, A. Santoro, F. Beech, J. Cryst. Growth 85 Ž1987. 632. w10bx High-Temperature Superconductors, Materials Research Society Symposium Proceedings 99, Mater. Res. Soc., Pittsburgh, PA, 1998, p. 515. w11x H. Ahinaga, K. Takita, H. Asano, K. Masuda, Physica C 161 Ž1989. 581. w12x A. Maeda, T. Yabe, K. Uchinokura, S. Tanaka, Jpn. J. Appl. Phys. 26 Ž1987. L1368.
F. Tao et al.r Materials Letters 39 (1999) 305–309 w13x E.M. McCarron III, C.C. Torardi, J.P. Attfield, K.J. Morrissey, A.W. Sleight, D.E. Cox, R.K. Borida, W.E. Farneth, R.B. Flippen, M.A. Subramanian, B. Lopdrup, S.J. Poon, in: High-Temperature Superconductors, Materials Research Society Symposium Proceedings 99, Mater. Res. Soc., Pittsburgh, PA, 1988, p. 101. w14x C.U. Segre, B. Dabrowski, D.G. Hinks, K. Zhung, J.D. Jorgensen, M.A. Beno, I.K. Schuller, Nature 329 Ž1987. 227.
309
w15x M.H. Ghandehari, S.G. Brass, J. Mater. Res. 4 Ž1989. 111. w16x S.G. Brass, M.H. Ghandehari, Appl. Phys. Lett. 23 Ž1988. 2235. w17x S.G. Brass, M.H. Ghandehari, Appl. Phys. A 48 Ž1989. 401. w18x W. Wong-Ng, B. Paretakin, E.R. Fuller Jr., J. Solid State Chem. 85 Ž1990. 117. w19x J.L. Tallon, N.E. Flower, Physica C 168 Ž1990. 65. w20x J.L. Tallon, N.E. Flower, Physica C 204 Ž1993. 237. w21x J.L. Tallon, B.E. Mellander, Science 258 Ž1992. 781.
Materials Letters 39 Ž1999. 305–309 www.elsevier.comrlocatermatlet
Effects of preparation condition on structure and superconductivity in the LaBCO system F. Tao
a,b,)
, G.C. Che a , X.J. Zhou c , Z. Zhao a , C. Dong a , S.L. Jia a , H. Chen b
a
a Chinese Academy of Sciences, Beijing, 100080, China Department of Materials Science, Sichuan UniÕersity, Chengdu, 610064, China c Yuzhou UniÕersity, Chongqing, 400000, China
Received 28 September 1998; accepted 18 December 1998
Abstract The effects of preparation condition on structure and superconductivity of LaBa 2 Cu 3 O y ŽLaBCO. system have been investigated, and the optimum preparation condition and superconductivity of Tc Ž0. s 97 K and Tc Žonset. s 101 K, which are the best results at present, have been achieved. The optimum preparation condition is A-B-C3-D-E. Investigations show that keeping LaBa 2 Cu 3 O y , being of tetragonal structure before oxygenation, at 3058C is a key procedure to obtain a single phase LaBa 2 Cu 3 Oy sample with the best superconductivity. q 1999 Published by Elsevier Science B.V. All rights reserved. Keywords: LaBa 2 Cu 3 O y ; Preparation condition; Structure; Superconductivity
1. Introduction Murphy et al. w1x and Hor et al. w2x first prepared LaBa 2 Cu 3 O y superconductors with Tc Ž0. greatly lower than 90 K in 1987. Much progress has been made to enhance its Tc for the past 10 years w3– 9,10a,10b,11–18x. Lindemer et al. obtained the best result with Tc Ž0. s 93 K in 1994 w18x. However, Tallon et al. w19–21x predicted that a superconducting transition temperature of 100 K should be achievable for LaBa 2 Cu 3 O y . Moreover, all the former investigators only investigated the effect of preparation condition on superconductivity, but have not investigated the effects of sample structure on superconductivity. In order to obtain and understand the optimum preparation condition and prepare high-quality single )
Corresponding author. E-mail: [email protected]
phase LaBa 2 Cu 3 O y superconductor with higher Tc , and try to prove Tallon’s prediction, this work investigated the preparation condition, structure, superconductivity and the effect of structure on superconductivity of LaBCO.
Fig. 1. The preparation condition of LaBa 2 Cu 3 O y .
00167-577Xr99r$ - see front matter q 1999 Published by Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 5 7 7 X Ž 9 9 . 0 0 0 2 5 - 7
306
F. Tao et al.r Materials Letters 39 (1999) 305–309
Fig. 2. The XRD patterns of LaBa 2 Cu 3 O y prepared by different preparation conditions.
F. Tao et al.r Materials Letters 39 (1999) 305–309
2. Experimental High-purity Ž99.99%. La 2 O 3 , BaCO 3 and CuO were used to prepare LaBa 2 Cu 3 O y samples. The La 2 O 3 powder was calcinated at 9508C for 20 h in air in order to eliminate absorbed or chemically bound products. The weighed, mixed, ground starting materials were calcinated at 8008C for 8 h and 8508C for 10 h, respectively. The ground powder was pressed into pellets, placed in an Al 2 O 3 boat and prepared by different preparation condition as shown in Fig. 1. The XRD diffraction of all samples were executed with a MXP18A-HF type diffractometer with CuK a radiation. The positions of reflections were calibrated using Si powder as internal standard. Lattice parameters were calculated with Finax and Lazy programmes. The samples were analyzed for
307
superconductivity using an ac magnetometer and standard four-probe technique.
3. Results and discussion XRD patterns show that the product calcinated at 8008C for 8 h and 8508C for 10 h is a multi-phase sample. Fig. 2c–b show that samples prepared by A-B-C1-C1X or A-B-C2-C2X are of an orthorhombic structure and contain the second phase BaCuO 2 represented with asterisk. Fig. 2a shows sample prepared by A-B-C3-C3X is a single phase sample with tetragonal structure. Fig. 2c, b and a also show the contents of BaCuO 2 in samples increase with the increase of partial pressure of oxygen used as prepa-
Fig. 3. Susceptibility and RrRŽ285 K. vs. temperature for LaBa 2 Cu 3 O y prepared by A-B-C3-D-E, A-B-C2-D-E and A-B-C1-D-E preparation conditions, respectively. v: by A-B-C3-D-E, ': by A-B-C2-D-E, l: A-B-C1-D-E.
308
F. Tao et al.r Materials Letters 39 (1999) 305–309
ration atmosphere wC1-C1X ŽO 2 . ) C2–C2X Žair. ) C3–C3X ŽN2 .x, and the structures of samples gradually change from orthorhombicity into tetragonal structure with the decrease of partial pressure of oxygen. So, in order to obtain single phase sample with tetragonal structure, it is necessary to execute Žc. procedure in N2 ŽC3-C3X .. Tc Ž0. of samples prepared by A-B-C1-C1X and A-B-C2-C2X is 54 and 52 K, respectively. The sample prepared by A-B-C3-C3X is nonsuperconducting which is in agreement with its tetragonal structure, nonsuperconducting phase. Fig. 2cX and bX show that samples prepared by A-B-C1-C-D-E and A-B-C2-D-E are of an orthorhombic structure and contain the second phase BaCuO 2 . Fig. 2aX shows that sample prepared by A-B-C3-D-E is single phase with orthorhombic structure. It can be seen from Fig. 2a and aX that sample prepared by A-B-C3-C3X-D-E obviously change from tetragonal into orthorhombic structure after oxygenation at 3058C for 60 h ŽD procedure., which can also be seen directly from the change of intensities of Ž020. and Ž200. reflection peaks. However, the structure of samples prepared by A-B-C1C1X and A-B-C2-C2X have not obviously changed after oxygenation at 3058C for 60 h. The sample prepared by A-B-C1-D or A-B-C2-D is a multi-phase sample which contains the second phase BaCuO 2 . It is concluded from Fig. 2aX , bX and cX that it is necessary to execute c procedure in N2 ŽC3. for obtaining a single phase LaBa 2 Cu 3 O y sample after oxygenation at 3058C for 60 h. Fig. 3 shows that Tc Ž0. and Tc Žonset. of sample prepared by A-B-C3-D-E is 97 K and 101 K, respectively, and the Tc Ž0. of samples prepared by A-B-C1D-E and A-B-C2-D-E are 91.5 and 93.5, respectively. The orthorhombic splitting factor ŽOS. in the unit cell defined with the formula, OS s 1000Ž b y a.rŽ b q a., where a and b represent the lattice parameters of unit cell, is often used to describe the orthorhombicity of RE-123 unit cell. Here it is used to describe the orthorhombicity of LaBa 2 Cu 3 O y unit cell in different preparation conditions. The OS factors of the samples prepared by A-B2C3-D-E, A-B-C2-D-E and A-B-C1-D-E conditions are 9.6, 5.4 and 5.0, respectively. This indicates that the LaBa 2 Cu 3 O y sample with largest OS factor pre-
pared by A-B2-C3-D-E condition have the best superconductivity. It was confirmed by superconductivity results.
4. Conclusions All theses investigations show that the optimum preparation condition is A-B-C3-D-E, and Žc. procedure executed in N2 is a key procedure to prepare single phase LaBa 2 Cu 3 O y superconductors with the best superconductivity. With the optimum condition, single phase LaBa 2 Cu 3 O y superconductors with Tc Ž0. s 97 K and Tc Žonset. s 101 K, which are the best results at present, was prepared. Moreover, investigation shows that Tc Ž0. of sample after oxygenation in O 2 at 3058C for 60 h is much lower than 97 K if sample has formed orthorhombic structure before executing oxygenation procedure.
References w1x D.W. Murphy, S.S. Unshine, R.B. Van Dover, R.J. Cava, B. Batlog, S.M. Zahurak, Phys. Rev. Lett. 58 Ž1988. 1888. w2x P.H. Hor, R.L. Meng, Y.Q. Wang, L. Gao, Z.J. Huang, J. Bechtold, K. Forster, C.W. Chu, Phys. Rev. Lett. 58 Ž1987. 1891. w3x T.B. Lindemer, B.C. Chakoumakos, E.D. Specht, R.K. Williams, Y.J. Chen, Physica C 231 Ž1994. 80. w4x T. Wada, H. Yamauchi, S. Tanaka, J. Am. Ceram. Soc. 75 Ž1992. 1705. w5x A. Maeda, T. Noda, H. Matsumoto, T. Wada, M. Izumi, T. Yabe, K. Uchinokura, S. Tanaka, J. Appl. Phys. 64 Ž1988. 4095. w6x T. Wada, N. Suzuhi, T. Maeda, A. Maeda, S. Uchida, K. Uchinokora, S. Tanaka, Appl. Phys. Lett. 52 Ž1988. 1989. w7x T. Wada, N. Suzuki, H. Yamauchi, S. Tanaka, A. Maeda, K. Uchiniokura, J. Am. Ceram. Soc. 72 Ž1989. 2000. w8x T. Wada, N. Suzuki, A. Waeda, T. Yabe, K. Uchinokura, S. Uchida, S. Tanaka, Phys. Rev. B 40 Ž1989. 9126. w9x M. Izumi, T. Yabe, T. Wada, A. Maeda, K. Uchinokura, S. Tanaka, H. Asano, Phys. Rev. B 40 Ž1989. 6771. w10ax S.A. Sunshine, L.F. Schneemeyer, J.V. Waszczck, D.W. Murphy, S. Miraglia, A. Santoro, F. Beech, J. Cryst. Growth 85 Ž1987. 632. w10bx High-Temperature Superconductors, Materials Research Society Symposium Proceedings 99, Mater. Res. Soc., Pittsburgh, PA, 1998, p. 515. w11x H. Ahinaga, K. Takita, H. Asano, K. Masuda, Physica C 161 Ž1989. 581. w12x A. Maeda, T. Yabe, K. Uchinokura, S. Tanaka, Jpn. J. Appl. Phys. 26 Ž1987. L1368.
F. Tao et al.r Materials Letters 39 (1999) 305–309 w13x E.M. McCarron III, C.C. Torardi, J.P. Attfield, K.J. Morrissey, A.W. Sleight, D.E. Cox, R.K. Borida, W.E. Farneth, R.B. Flippen, M.A. Subramanian, B. Lopdrup, S.J. Poon, in: High-Temperature Superconductors, Materials Research Society Symposium Proceedings 99, Mater. Res. Soc., Pittsburgh, PA, 1988, p. 101. w14x C.U. Segre, B. Dabrowski, D.G. Hinks, K. Zhung, J.D. Jorgensen, M.A. Beno, I.K. Schuller, Nature 329 Ž1987. 227.
309
w15x M.H. Ghandehari, S.G. Brass, J. Mater. Res. 4 Ž1989. 111. w16x S.G. Brass, M.H. Ghandehari, Appl. Phys. Lett. 23 Ž1988. 2235. w17x S.G. Brass, M.H. Ghandehari, Appl. Phys. A 48 Ž1989. 401. w18x W. Wong-Ng, B. Paretakin, E.R. Fuller Jr., J. Solid State Chem. 85 Ž1990. 117. w19x J.L. Tallon, N.E. Flower, Physica C 168 Ž1990. 65. w20x J.L. Tallon, N.E. Flower, Physica C 204 Ž1993. 237. w21x J.L. Tallon, B.E. Mellander, Science 258 Ž1992. 781.