Critical current density and irreversibility line of CuBa{sub 2}Ca{sub 3}Cu{sub 4}O{sub y}

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Advances in Cryogenic Engineering

OSTI ID:482065

Iyo, A; Tokumoto, M; Ihara, H ^[1]

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1. Electrotechnical Lab., Tsukuba, Ibaraki (Japan); and others

The critical current density and irreversibility line of the single-phase polycrystalline sample of CuBa{sub 2}Ca{sub 3}Cu{sub 4}O{sub y} with T{sub c}= 117 K have been estimated from measurements of magnetic hysteresis loops assuming Bean critical state model. Simple power law relations, J{sub c}{proportional_to}H{sup {minus}m}, are observed in the magnetic field dependence of the intragrain J{sub c}. Values of the intragrain J{sub c} in a magnetic field of 1 T are about 10{sup 6} and 10{sup 4} A/cm{sup 2} at temperatures of 5 and 77 K, respectively. An exponential decay of the J{sub c} with increasing temperature, J{sub c}{proportional_to}exp({minus}T/T{sub 0}), is observed below 60 K. The characteristic temperature T{sub 0} of Cu-1234 is T{sub 0}= 16.1 K in a magnetic field of 1.0 T. The dependence of the J{sub c} on temperature is relatively small among the oxide superconductors. Simple power law relations, J{sub c}{proportional_to}(1{minus}T/T{sub c}){sup n}, are found in whole ranges of the temperature and magnetic field. The value of n is 5.24 for a magnetic field of 1.0 T. The irreversibility fields at 70 and 77 K are estimated to be 9.5 and 3.7 T, respectively. The temperature dependence of the H{sub irr} is fitted by H{sub irr}=a(1{minus}T/T{sub c}){sup n} with a=2130 and n=5.91.

• OSTI ID: 482065
• Report Number(s): CONF-950722--
• Journal Information: Advances in Cryogenic Engineering, Journal Name: Advances in Cryogenic Engineering Vol. 42B; ISSN 0065-2482; ISSN ACYEAC
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CALCIUM OXIDES
COPPER OXIDES
CRITICAL CURRENT
SCALING LAWS