BRYLEWSKI T, PRZYBYLSKI K, MORAWSKI A, et al.Soft-chemistry synthesis of Ba2Ca2Cu3Ox precursor and characterization of high-Tc Hg0.8Pb0.2Ba2Ca2Cu3O8+δ superconductor.Journal of Advanced Ceramics, 2016, 5(3): 185-196.https://doi.org/10.1007/s40145-016-0189-x
The paper describes the sol–gel process applied to synthesize a mercury-free Ba2Ca2Cu3Ox precursor and the physicochemical properties of an Hg0.8Pb0.2Ba2Ca2Cu3O8+δ high-temperature superconductor (HTS) polycrystalline sample. The Ba2Ca2Cu3Ox precursor with desired chemical and phase compositions was obtained using EDTA gel process followed by decomposition and calcination under optimized conditions. An Hg0.8Pb0.2Ba2Ca2Cu3O8+δ superconductor with a fine-grained microstructure, composed predominantly of the (Hg,Pb)-1223 phase in the form of plate-like crystallites or oval grains and with advantageous magnetic properties (Tc(on) = 129.2 K, ΔTc = 6.5 K), was synthesized using the high-pressure crystallization method. At 20 K and 1 T, the critical current density of the studied sample was approximately 26 A/mm2, while at 4 K and 1 T it increased to 155 A/mm2. The high volume fraction of the (Hg,Pb)-1223 phase (89.1%) in the high-Tc sample was associated with the low value of the average copper valence (2.11) in the calcinated Ba2Ca2Cu3Ox precursor. Small amounts of non-superconducting secondary phases—BaCuO2, CaO, CaHgO2, CuO, Ca2CuO, BaPbO3—were also identified within the microstructure of Hg0.8Pb0.2Ba2Ca2Cu3O8+δ.
Soft-chemistry synthesis of Ba2Ca2Cu3Ox precursor and characterization of high-Tc Hg0.8Pb0.2Ba2Ca2Cu3O8+δ superconductor
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T. BRYLEWSKIa(
), K. PRZYBYLSKIa, A. MORAWSKIb, D. GAJDAc, T. CETNERb, J. CHMISTd
AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Al. Mickiewicza 30, 30-059Krakow, Poland
Institute of High Pressure Physics of the Polish Academy of Sciences, Superconductor Laboratory NL-6, ul. Prymasa Tysiąclecia 98, 00-893Warsaw, Poland
International Laboratory of High Magnetic Fields and Low Temperatures, ul. Gajowicka 95, 53-421Wroclaw, Poland
AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Al. Mickiewicza 30, 30-059Krakow, Poland
Abstract
The paper describes the sol–gel process applied to synthesize a mercury-free Ba2Ca2Cu3Ox precursor and the physicochemical properties of an Hg0.8Pb0.2Ba2Ca2Cu3O8+δ high-temperature superconductor (HTS) polycrystalline sample. The Ba2Ca2Cu3Ox precursor with desired chemical and phase compositions was obtained using EDTA gel process followed by decomposition and calcination under optimized conditions. An Hg0.8Pb0.2Ba2Ca2Cu3O8+δ superconductor with a fine-grained microstructure, composed predominantly of the (Hg,Pb)-1223 phase in the form of plate-like crystallites or oval grains and with advantageous magnetic properties (Tc(on) = 129.2 K, ΔTc = 6.5 K), was synthesized using the high-pressure crystallization method. At 20 K and 1 T, the critical current density of the studied sample was approximately 26 A/mm2, while at 4 K and 1 T it increased to 155 A/mm2. The high volume fraction of the (Hg,Pb)-1223 phase (89.1%) in the high-Tc sample was associated with the low value of the average copper valence (2.11) in the calcinated Ba2Ca2Cu3Ox precursor. Small amounts of non-superconducting secondary phases—BaCuO2, CaO, CaHgO2, CuO, Ca2CuO, BaPbO3—were also identified within the microstructure of Hg0.8Pb0.2Ba2Ca2Cu3O8+δ.
Keywords:superconductor, microstructure, EDTA gel process, secondary phase
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The authors would like to express their gratitude to Mrs. B. Trybalska from the Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Krakow, Poland, for her assistance in SEM–EDX observations.
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