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Crystal growth of a new orthorhombic ErBa(Cu,Pt)O4 material: Crystal chemistry and characterization
Journal of Crystal Growth 85 (1987) 599—601 North-Holland, Amsterdam
59~
CRYSTAL GROWTH OF A NEW ORTHORHOMBIC ErBa(Cu,Pt)O4 MATERIAL: CRYSTAL CHEMISTRY AND CHARACTERIZATION 1. SHISHIDO, T. FUKUDA, N. TOYOTA, K. UKEI and T. SASAKI Institute for Materials Research (KINKEN), Tohoku University, Katahira, Sendai 980, Japan Received 10 September 1987
A new compound in the quaternary oxide system, Er Ba Cu Pt 0, was discovered. Single crystals were grown using CuO as a flux in a platinum crucible by a slow cooling method. The platinum was supplied from the inner wall of the platinum crucible. Chemical analysis revealed the chemical composition of this compound to be ErBa1 03Cu0~7Pt046O4~ The crystal system was found to be orthorhombic (space group Pcmn) with average unit cell dimensions a 10.287(3) A, b = 5.659(1) A and c = 13.157(3) A. We propose the chemical formula of this compound as ErBa(Cu,Pt)04. A large, but broad diamagnetic transition, which should come from the superconducting state, was observed below 80 90 K in single crystal aggregates.
Recently studies of superconducting oxide materials have developed rapidly and achievements in this field have become a center of attraction. A ternary oxide system La—Ba Cu 0 with a K2NiF4 type structure has been revealed by Bednorz and Muller [1] to exhibit high temperature superconductivity with 7~in the 30 K range. Following this exciting breakthrough, et al. [2], and, independently, Hikami et al. Wu [3] found superconductivity with 7~ 90 K in YBa 2Cu3 07 Extensive efforts have been and are still being made to synthesize a new class of oxides in expectation of even higher T~materials, This letter reports on the newly discovered orthorhombic Er—Ba Cu Pt 0 system with a chemical formula ErBa(Cu,Pt)0 4. The preparation of single crystals, chemical analyses, X-ray structural studies and AC susceptibility measurements are described, The single crystals were obtained as follows. Chemical reagent grade Er203 (99.9%, Nippon Yttrium Co.), Ba(OH)2’ 8H20 (analytical grade, Wako Chemicals) and CuO (99.9%, Wako Chemicals) were weighed in molar ratios of 1 : 4: 6 and were well mixed. The mixture was put in an alumina crucible of high purity and heated in air at 930°Cfor 24 h. The powder specimen obtained was reground. Then to this powder specimen was
added CuO as a flux (self component flux) in a weight ratio of 2: 1. This mixture was placed in a platinum crucible of inside diameter 50 mm and depth 50 mm. The mixture was heated and held at 1100°Cfor 1 h, and then slowly cooled down to 900°Cat a rate of 10°Ch-’, in an oxygen stream of 100 ml mm 3 in the Platy single crystals (1 x 1inxthe 0.2 solidified mm maximum size) were obtained flux ‘.
=
~.
away from the inner wall of the platinum crucible: these were of ErBa2Cu3O7 a well-established ternary oxide compound. In addition, crystals of an unknown compound in the form of rectangular prisms, with coagulated an average onsizetheof bottom 0.7 X 0.1ofX 0.1 3, were the mm platinum crucible. Fig. 1 shows a scanning electron microscope (SEM) image of an aggregate of rectangular prisms. These crystals have a black, metallic luster with sharp edges, and are brittle. A chemical analysis was carried out on powdered single crystals of the unknown cornpound dissolved in 7N HNO3 solution. Continuous emission spectral analysis using the inductively coupled plasma (ICP) technique was applied to the solution. It revealed that the crystals were of the quaternary oxide, ErBa103Cu077Pt046O434. The high concentration of platinum was supplied from the inner wall of the platinum crucible. An
0022-0248/87/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
,~,
600
T. Shishido et al.
Growth of new orthorhombic ErBa(Cu,Pt)0
4 material
,
,~
~
/
,~
j~
-
energy dispersive X-ray analysis (EDX) taken on a surface of the rectangular prism crystal is shown in fig. 2. Results of the EDX support the abovementioned results of chemical analysis. Electron probe microanalysis (EPMA) taken on a cleaved plane showed that the Er, Ba, Cu and Pt were uniformly distributed. This indicates that no segregation occurred during crystallization. A crystal structure analysis for the rectangular prism crystals was carried out by using an X-ray powder diffractometer and a four-circle X-ray diffractometer with graphite-monochromatized Mo K~radiation, employing the 0 20 scan technique. The crystal data are summarized in table 1. Crystallographic investigations revealed an orthorhombic symmetry (its space group is Pcmn) with average unit cell dimensions a 10.287(3) A. b 5.659(1) A and c = 13.157(3) A. The elongation axis of the single crystal is the b-axis and the developed habits are {100} and {001}. This new compound is distinct from well-established phases such as La185 Sr015Cu04 (K2NiF4-type) [4] and YBa2Cu3O7 [5], as shown in table 1. From the preliminary results of crystal structure analysis (also including the intensity calculation) combined with the above-mentioned chemical composition, we propose, for this new compound, that the chemical formula is ErBa(Cu,Pt)04 and that the number of formula units in the unit cell (Z) is 4. We measured the AC magnetic susceptibility as a function of temperature for two aggregates of —
,~
ft tJ
lfl~~ U Fig. 2. X.ray energy dispersive spectrum of the surface of ErBa103Cu077 Pt0
0434 single crystal.
the single crystals as shown in fig. 1. Fig. 3 shows the diamagnetic transitions of two different aggregates. A large diamagnetic signal was reproducibly observed in each specimen below 80 90 K. These transitions are strong but somewhat broad. If they are attributed to the Meissner effect due to the superconducting transition, several tens of percent of the total volume should be in a superconducting state. It is necessary, however, to take into account the following two points. First, the AC magnetic susceptibility measurement often overestimates the fractional volume in a superconducting state, due to the magnetic shielding effect. Second, we cannot completely exclude the possibility that the measured aggregate specimens may have inclusions of the other high 1~superconducting phases(s) such as the K2NiF4 and YBa2Cu3 07 type, although the X-ray diffraction did not show any indication of these well established phases. These are the reasons why we cannot draw, at present, a definitive conclusion as to ,~
/
T. Shishido et al.
Growth of new orthorhombic ErBa(Cu,Pt)0
4 material
601
ErBa1.03Cu0.17Pt0.4604.34 I
I
I
I
I
I
I
I
90K
0
T (K) Fig. 3. Temperature dependence of the real part of the AC magnetic susceptibility for aggregate single crystals of ErBa1 03Cu077 ~~ 0~~ Two specimens with EBCPO-F9 are recovered from the same batch. The total weight and the fraction change in inductance are indicated in the figure.
whether the newly discovered orthorhombic cornpound with the proposed chemical formula ErBa(Cu,Pt)04 really exhibits superconductivity in the 80—90 K range, or not. More detailed investiga-
The authors wish to acknowledge Mr. S. Oki for the X-ray analysis and Mr. K. Takada for the chemical analysis and Mr. M. Shimizu for performing the EDXA and EPMA. They also acknowledge Professors Y. Muto and T. Fukase for their encouragement, and Dr. S. Hosoya for valuable
Table I Crystal data of ErBa103Cu077Pt0460434 Chemical formula
Crystal system
Space group
ErBa(Cu,Pt)04 (this work)
Orthorhombic
Pcmn
tions on the crystal structure analysis, supercon ducting properties and thermal properties (phase transitions, etc.) are now in progress.
a 10.287(3) A b 5.659(1) A c 13.157(3)A 3 ZV= 4765.9 A
discussions.
References
La 1 85Sr015Cu04 (Cava et al. [4])
Orthorhombic
Bmab
Orthorhombic
Pmmm
5.3252(1) A 5.3546(1) A = 13.1844(1) 3 A zv — 4375.9 A
a b c
=
[1] J.G. Bednorz and K.A. Muller, Z. Physik B64 (1986) 189. [2] M.K. Wu, Ashburn, Torng, P.H. Hor, L. Gao, Z.J.J.R. Huang, Y.Q. C.J. Wang and C.W. Chu, R.L. Phys.Meng, Rev. Letters 58 (1987) 908. [3] S. Hikami, T. Hirai and S. Kagoshima, Japan. J. AppI.
YBa 2Cu3O7 ~ (Izumi et al. [5])
a 3.8829(3) A b = 3.8223(3) A c = 11.690(1)3 A zV 173.5 A
Phys. 26 (1987) L314.
[41R.J. Cava, A. Santoro, D.W. Johnson, Jr. and W.W. Rhodes, [5] preprint. F. Izumi, H. Asano, T. Ishigaki, E. Takayama Muromachi, Y. Uchida, N. Watanabe and T. Nishikawa, Japan. J. AppI. Phys. 26 (1987) L649.
59~
CRYSTAL GROWTH OF A NEW ORTHORHOMBIC ErBa(Cu,Pt)O4 MATERIAL: CRYSTAL CHEMISTRY AND CHARACTERIZATION 1. SHISHIDO, T. FUKUDA, N. TOYOTA, K. UKEI and T. SASAKI Institute for Materials Research (KINKEN), Tohoku University, Katahira, Sendai 980, Japan Received 10 September 1987
A new compound in the quaternary oxide system, Er Ba Cu Pt 0, was discovered. Single crystals were grown using CuO as a flux in a platinum crucible by a slow cooling method. The platinum was supplied from the inner wall of the platinum crucible. Chemical analysis revealed the chemical composition of this compound to be ErBa1 03Cu0~7Pt046O4~ The crystal system was found to be orthorhombic (space group Pcmn) with average unit cell dimensions a 10.287(3) A, b = 5.659(1) A and c = 13.157(3) A. We propose the chemical formula of this compound as ErBa(Cu,Pt)04. A large, but broad diamagnetic transition, which should come from the superconducting state, was observed below 80 90 K in single crystal aggregates.
Recently studies of superconducting oxide materials have developed rapidly and achievements in this field have become a center of attraction. A ternary oxide system La—Ba Cu 0 with a K2NiF4 type structure has been revealed by Bednorz and Muller [1] to exhibit high temperature superconductivity with 7~in the 30 K range. Following this exciting breakthrough, et al. [2], and, independently, Hikami et al. Wu [3] found superconductivity with 7~ 90 K in YBa 2Cu3 07 Extensive efforts have been and are still being made to synthesize a new class of oxides in expectation of even higher T~materials, This letter reports on the newly discovered orthorhombic Er—Ba Cu Pt 0 system with a chemical formula ErBa(Cu,Pt)0 4. The preparation of single crystals, chemical analyses, X-ray structural studies and AC susceptibility measurements are described, The single crystals were obtained as follows. Chemical reagent grade Er203 (99.9%, Nippon Yttrium Co.), Ba(OH)2’ 8H20 (analytical grade, Wako Chemicals) and CuO (99.9%, Wako Chemicals) were weighed in molar ratios of 1 : 4: 6 and were well mixed. The mixture was put in an alumina crucible of high purity and heated in air at 930°Cfor 24 h. The powder specimen obtained was reground. Then to this powder specimen was
added CuO as a flux (self component flux) in a weight ratio of 2: 1. This mixture was placed in a platinum crucible of inside diameter 50 mm and depth 50 mm. The mixture was heated and held at 1100°Cfor 1 h, and then slowly cooled down to 900°Cat a rate of 10°Ch-’, in an oxygen stream of 100 ml mm 3 in the Platy single crystals (1 x 1inxthe 0.2 solidified mm maximum size) were obtained flux ‘.
=
~.
away from the inner wall of the platinum crucible: these were of ErBa2Cu3O7 a well-established ternary oxide compound. In addition, crystals of an unknown compound in the form of rectangular prisms, with coagulated an average onsizetheof bottom 0.7 X 0.1ofX 0.1 3, were the mm platinum crucible. Fig. 1 shows a scanning electron microscope (SEM) image of an aggregate of rectangular prisms. These crystals have a black, metallic luster with sharp edges, and are brittle. A chemical analysis was carried out on powdered single crystals of the unknown cornpound dissolved in 7N HNO3 solution. Continuous emission spectral analysis using the inductively coupled plasma (ICP) technique was applied to the solution. It revealed that the crystals were of the quaternary oxide, ErBa103Cu077Pt046O434. The high concentration of platinum was supplied from the inner wall of the platinum crucible. An
0022-0248/87/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
,~,
600
T. Shishido et al.
Growth of new orthorhombic ErBa(Cu,Pt)0
4 material
,
,~
~
/
,~
j~
-
energy dispersive X-ray analysis (EDX) taken on a surface of the rectangular prism crystal is shown in fig. 2. Results of the EDX support the abovementioned results of chemical analysis. Electron probe microanalysis (EPMA) taken on a cleaved plane showed that the Er, Ba, Cu and Pt were uniformly distributed. This indicates that no segregation occurred during crystallization. A crystal structure analysis for the rectangular prism crystals was carried out by using an X-ray powder diffractometer and a four-circle X-ray diffractometer with graphite-monochromatized Mo K~radiation, employing the 0 20 scan technique. The crystal data are summarized in table 1. Crystallographic investigations revealed an orthorhombic symmetry (its space group is Pcmn) with average unit cell dimensions a 10.287(3) A. b 5.659(1) A and c = 13.157(3) A. The elongation axis of the single crystal is the b-axis and the developed habits are {100} and {001}. This new compound is distinct from well-established phases such as La185 Sr015Cu04 (K2NiF4-type) [4] and YBa2Cu3O7 [5], as shown in table 1. From the preliminary results of crystal structure analysis (also including the intensity calculation) combined with the above-mentioned chemical composition, we propose, for this new compound, that the chemical formula is ErBa(Cu,Pt)04 and that the number of formula units in the unit cell (Z) is 4. We measured the AC magnetic susceptibility as a function of temperature for two aggregates of —
,~
ft tJ
lfl~~ U Fig. 2. X.ray energy dispersive spectrum of the surface of ErBa103Cu077 Pt0
0434 single crystal.
the single crystals as shown in fig. 1. Fig. 3 shows the diamagnetic transitions of two different aggregates. A large diamagnetic signal was reproducibly observed in each specimen below 80 90 K. These transitions are strong but somewhat broad. If they are attributed to the Meissner effect due to the superconducting transition, several tens of percent of the total volume should be in a superconducting state. It is necessary, however, to take into account the following two points. First, the AC magnetic susceptibility measurement often overestimates the fractional volume in a superconducting state, due to the magnetic shielding effect. Second, we cannot completely exclude the possibility that the measured aggregate specimens may have inclusions of the other high 1~superconducting phases(s) such as the K2NiF4 and YBa2Cu3 07 type, although the X-ray diffraction did not show any indication of these well established phases. These are the reasons why we cannot draw, at present, a definitive conclusion as to ,~
/
T. Shishido et al.
Growth of new orthorhombic ErBa(Cu,Pt)0
4 material
601
ErBa1.03Cu0.17Pt0.4604.34 I
I
I
I
I
I
I
I
90K
0
T (K) Fig. 3. Temperature dependence of the real part of the AC magnetic susceptibility for aggregate single crystals of ErBa1 03Cu077 ~~ 0~~ Two specimens with EBCPO-F9 are recovered from the same batch. The total weight and the fraction change in inductance are indicated in the figure.
whether the newly discovered orthorhombic cornpound with the proposed chemical formula ErBa(Cu,Pt)04 really exhibits superconductivity in the 80—90 K range, or not. More detailed investiga-
The authors wish to acknowledge Mr. S. Oki for the X-ray analysis and Mr. K. Takada for the chemical analysis and Mr. M. Shimizu for performing the EDXA and EPMA. They also acknowledge Professors Y. Muto and T. Fukase for their encouragement, and Dr. S. Hosoya for valuable
Table I Crystal data of ErBa103Cu077Pt0460434 Chemical formula
Crystal system
Space group
ErBa(Cu,Pt)04 (this work)
Orthorhombic
Pcmn
tions on the crystal structure analysis, supercon ducting properties and thermal properties (phase transitions, etc.) are now in progress.
a 10.287(3) A b 5.659(1) A c 13.157(3)A 3 ZV= 4765.9 A
discussions.
References
La 1 85Sr015Cu04 (Cava et al. [4])
Orthorhombic
Bmab
Orthorhombic
Pmmm
5.3252(1) A 5.3546(1) A = 13.1844(1) 3 A zv — 4375.9 A
a b c
=
[1] J.G. Bednorz and K.A. Muller, Z. Physik B64 (1986) 189. [2] M.K. Wu, Ashburn, Torng, P.H. Hor, L. Gao, Z.J.J.R. Huang, Y.Q. C.J. Wang and C.W. Chu, R.L. Phys.Meng, Rev. Letters 58 (1987) 908. [3] S. Hikami, T. Hirai and S. Kagoshima, Japan. J. AppI.
YBa 2Cu3O7 ~ (Izumi et al. [5])
a 3.8829(3) A b = 3.8223(3) A c = 11.690(1)3 A zV 173.5 A
Phys. 26 (1987) L314.
[41R.J. Cava, A. Santoro, D.W. Johnson, Jr. and W.W. Rhodes, [5] preprint. F. Izumi, H. Asano, T. Ishigaki, E. Takayama Muromachi, Y. Uchida, N. Watanabe and T. Nishikawa, Japan. J. AppI. Phys. 26 (1987) L649.