Superconductivity of rare earth-barium-copper oxides

Fisk, Z.; Thompson, J. D.; Zirngiebl, E.; Smith, J. L.; Cheong, S. W.

doi:10.1016/0038-1098(87)90038-x

Cited by 182 publications

(29 citation statements)

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“…In R-123 systems, magnetic moment of R does not contribute to superconducting properties, except for Ce, Tb and Pr [11]. Prsubstituted systems become nonsuperconductor above x cr , where as, in the present study we observe increase in T c in with increase in Pr concentration.…”

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“…The Pr-substituted R-123 compounds also show rare earth ion effect and for every x cr (critical Pr concentration) with respect to the R ion, superconductivity is totally suppressed [6,7]. In R-123 systems, magnetic moment of R does not contribute to superconducting properties, except for Ce, Tb and Pr [11]. Prsubstituted systems become nonsuperconductor above x cr , where as, in the present study we observe increase in T c in with increase in Pr concentration.…”

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confidence: 99%

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Studies on La2−xPrxCayBa2Cu4+yOz (x=0.1–0.5, y=2x) type mixed oxide superconductors

Rayaprol

Mavani

Rana

et al. 2003

Solid State Communications

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The La 2-x Pr x Ca y Ba 2 Cu 4+y O z (LaPrCaBCO) mixed oxides have been studied for their structural and superconducting properties using X-ray diffraction (XRD), d. c. resistivity, d. c. susceptibility and iodometric double titration. All the LaPrCaBCO samples for x = 0.1 -0.5, exhibit tetragonal crystalline structure with P 4/mmm space group as determined by Rietveld analysis of the X-ray diffraction data. With increasing x, enhancement in T c is observed, which is quite interesting for Pr substituted high T c oxides. Maximum T c ~ 58 K has been observed for x = 0.5 (La-2125 stoichiometry). The results of structural studies and superconducting property measurements are presented in light of increase in T c in LaPrCaBCO system with increasing Pr concentration. Keywords:La 1. INTRODUCTIONThe substitution of Pr in R-123 (R = rare earth) and related systems has been widely studied, for its role in suppressing superconductivity either due to hybridization between Pr (4f) and conducting CuO 2 (2p) plane leading to localization of mobile charge carriers and/or hole filling by fluctuating valence of Pr (3+ or 4+) at rare earth or even at Ba (Barium) site [1][2][3][4][5]. Even though many studies have been carried out on these compounds, yet the correct explanation for such a phenomenon is still a matter of debate. Majority of Pr substituted R-123 and derived systems have shown decrease in T c with increasing Pr concentration. The Pr-substituted R-123 compounds also show rare earth ion effect and for every x cr (critical Pr concentration) with respect to the R ion, superconductivity is totally suppressed [6,7]. In R-123 systems, magnetic moment of R does not contribute to superconducting properties, except for Ce, Tb and Pr [11]. Prsubstituted systems become nonsuperconductor above x cr , where as, in the present study we observe increase in T c in with increase in Pr concentration. EXPERIMENTALAll the samples of LaPrCaBCO series (x = 0.1 -0.5) were synthesized by solid state reaction method. The high purity (99.9+ %) starting compounds of La 2 O 3 , BaCO 3 , CaCO 3 , CuO and Pr 6 O 11 were taken in stoichiometric quantities and grinded thoroughly using agate and mortar under acetone. The calcination and sintering of these compounds were carried out in pellet form in the temperature range of 930 -940 0 C for about 72 hrs with intermediate grindings. Thus prepared samples were annealed in oxygen at 500 0 C for about 24 hrs and then slow cooled to room temperature.The samples were characterized for their structural properties by X-ray diffraction (Cu-K α , λ = 1.5405 Å) at room temperature. All the XRD patterns show single phase formation. The patterns were then fitted by Rietveld analysis using FULLPROF program [12]. The results show that there is no structural transition in the entire doping range, as all the samples are tetragonal, with decreasing unit cell parameters and volume. The transition temperature were recorded by four probe d. c. resistivity method and verified by d. c. susceptibility method, using a...

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confidence: 67%

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confidence: 99%

Studies on La2−xPrxCayBa2Cu4+yOz (x=0.1–0.5, y=2x) type mixed oxide superconductors

Rayaprol

Mavani

Rana

et al. 2003

Solid State Communications

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“…6 shows magnetic ordering of gadolinium spins at T N = 2.24 K for a crystallographically ordered compound of gadolinium [13]. From the data, which includes an extrapolation to T = 0 in the inset, we can see that the full magnetic entropy of R In 8 is available below T = 6 K. This is a fine example of what we call local-moment behavior.…”

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confidence: 85%

Magnetism of actinide compounds

Smith

Brown

Cooper

et al. 1987

Journal of Magnetism and Magnetic Materials

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“…According to Aliabadi et al [6], to have improvement in T c , one should pump more holes from the chains to the oxygen sites of the planes. Fisk et al [7] and Horet et al [8] have shown that in YBCO system superconductors, substitution at the rare earth site or alkaline-earth site would not change T c considerably. But substitution at the oxygen site is very crucial in the formation of superconductors.…”

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Fluorine Doping Effect in the New Superconducting Y3Ba5Cu8Oy Compound

Srinivasan

Thomas²,

Padaikathan³

2011

JMMCE

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Superconductivity of rare earth-barium-copper oxides

Cited by 182 publications

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Studies on La2−xPrxCayBa2Cu4+yOz (x=0.1–0.5, y=2x) type mixed oxide superconductors

Studies on La2−xPrxCayBa2Cu4+yOz (x=0.1–0.5, y=2x) type mixed oxide superconductors

Magnetism of actinide compounds

Fluorine Doping Effect in the New Superconducting Y<sub>3</sub>Ba<sub>5</sub>Cu<sub>8</sub>O<sub>y</sub> Compound

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Superconductivity of rare earth-barium-copper oxides

Cited by 182 publications

References 1 publication

Studies on La2−xPrxCayBa2Cu4+yOz (x=0.1–0.5, y=2x) type mixed oxide superconductors

Studies on La2−xPrxCayBa2Cu4+yOz (x=0.1–0.5, y=2x) type mixed oxide superconductors

Magnetism of actinide compounds

Fluorine Doping Effect in the New Superconducting Y&lt;sub&gt;3&lt;/sub&gt;Ba&lt;sub&gt;5&lt;/sub&gt;Cu&lt;sub&gt;8&lt;/sub&gt;O&lt;sub&gt;y&lt;/sub&gt; Compound

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Fluorine Doping Effect in the New Superconducting Y<sub>3</sub>Ba<sub>5</sub>Cu<sub>8</sub>O<sub>y</sub> Compound