# Specific heat of YBa 2 Cu 3 O 7-x from 4.2 to 60 K

TL;DR: In this paper, the specific heat of superconducting oxide compound, YBa2Cu3O7 −x, was studied using a quasiadiabatic calorimeter from 4.2 to 60 K.

Abstract: The specific heat of superconducting oxide compound, YBa2Cu3O7 −x
, is studied using a quasi-adiabatic calorimeter from 4.2 to 60 K. The analysis of the specific heat data below 15 K gives a value of 17 mJ/mole K2 for the electronic heat capacity coefficient. The value ofθ
D(0) is determined to be 397±8 K. The variation ofθ
D with temperature was calculated in the temperature range 4.2 to 60 K.

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TL;DR: In this paper, the specific heat of samples of Y1−xPrxBa2Cu3O7−y for x = 0.5 has been measured from 4.5 to 65 K using a quasi-adiabatic calorimeter.

Abstract: The specific heat of samples of Y1−xPrxBa2Cu3O7−y for x = 0.1 to 0.5 has been measured from 4.5 to 65 K using a quasi-adiabatic calorimeter. A plot of C/T vs T2 shows a linear behavior below 20 K. The excess specific heat due to praseodymium in all the compounds is obtained by subtracting the specific heat of YBa2Cu3O7−x from the that of doped compound. The excess specific heat shows a peak near 19 K and its height decreases with increase in x. The excess specific heat could be interpreted on the basis of Schottky anomalies due to Pr3+ and Pr4+ ions, the peak at 19 K arising from the former. The fraction of Pr3+ ion obtained from a fit to the specific heat curves decreases from 0.30 for x = 0.1 to 0.05 for x = 0.5.

17 citations

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01 Jan 1988TL;DR: In this article, specific heat measurements were made on single phase materials of Y1-x PrxBa2Cu3O7-y (x = 0 to 0.5) from 4.2 to 60 K using a quasi-adiabatic vacum calorimeter by pulse method of heating.

Abstract: Specific heat measurements were made on single phase materials of Y1-x PrxBa2Cu3O7-y (x = 0 to 0.5) from 4.2 to 60 K using a quasi-adiabatic vacum calorimeter by pulse method of heating. The oxygen deficiency, y, was determined by iodimetry to be 0.15 + 0.05 for x = 0.1 and increased to 0.24 ± 0.05 as x reached 0.5. The Tc was measured both resistively and inductively. A plot of C/T against T2 shows a linear behaviour below 20 K. The contribution to the specific heat linear in temperature increases as the concentration x of Pr increases. Subtracting the specific heat of YBa2Cu3O7-y from that of the praseodymium doped compound, the excess specific heat due to one mole of Pr is determined for each value of x. This excess contribution decreases as x increases. The excess contribution is interpreted as due to the Schottky anomaly of Pr3+ and Pr4+ and the concentration of Pr3+ was found to decrease from 30% for x = 0.1 to 5% for x = 0.5.

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TL;DR: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure.

Abstract: A stable and reproducible superconductivity transition between 80 and 93 K has been unambiguously observed both resistively and magnetically in a new Y-Ba-Cu-O compound system at ambient pressure. An estimated upper critical field H c2(0) between 80 and 180 T was obtained.

5,965 citations

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TL;DR: Results confirm that the material is a bulk superconductor with BCS-like behavior and the lattice contribution can be fitted to a Debye specific heat with FTHETA/sub D/approx.

Abstract: The specific heat of the ceramic superconductor YBa/sub 2/Cu/sub 3/O/sub 7-//sub delta/ has been measured in the vicinity of the transition temperature T/sub c/ = 90 K, using a combination of ac and heat-pulse calorimetry A step change deltaC/sub p/ = 62 mJ/g K is observed at T/sub c/ which, when divided by the electronic contribution to the heat capacity estimated from susceptibility data, gives a value close to that expected from Bardeen-Cooper-Schrieffer (BCS) theory These results confirm that the material is a bulk superconductor with BCS-like behavior The lattice contribution can be fitted to a Debye specific heat with FTHETA/sub D/approx =440 K

111 citations

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TL;DR: Heat-capacity measurements on a well-characterized sample of YBa/sub 2/Cu/sub 3/O/sub 6.85/ yield ..delta..C/sub p//T/sub c/approx. =20 mJ (mole Cu)/sup -1/ K/sup -2/, essentially the same value found previously for La/sub 1.85.

Abstract: Our heat-capacity measurements on a well-characterized sample of YBa/sub 2/Cu/sub 3/O/sub 6.85/ yield ..delta..C/sub p//T/sub c/approx. =20 mJ (mole Cu)/sup -1/ K/sup -2/, essentially the same value found previously for La/sub 1.85/Sr/sub 0.15/CuO/sub 4/. We combine this finding with independently estimated values of ..gamma.., the electronic specific-heat coefficient, to show that ..beta.. = ..delta..C/sub p//..gamma..T/sub c/ is (1) well outside the weak-coupling regime (..beta../sub BCS/ = 1.43) for the Y-based compound (T/sub c/ = 93 K) and La-based compound (T/sub c/ = 31 K), and (2) larger by about a factor of 2 in the Y-based compound compared to the La-based compound, the latter having a ..beta.. value in the same numerical range (2--3) as previously studied strong-coupling superconductors.

67 citations

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TL;DR: In this article, a two-dimensional Cu-O network with square-pyramidal and square-planar coordinated Cu atoms was characterized by thermogravimetry, differential thermal analysis, X-ray and neutron diffraction.

Abstract: YBa2Cu3O7 superconductors with inductive transitions as narrow as 0.45 K above 90 K were synthetized. Samples were characterized by thermogravimetry, differential thermal analysis, X-ray and neutron diffraction. The structure is characterized by a two-dimensional Cu-O network with square-pyramidal and square-planar coordinated Cu atoms. Results show a clear metallic behaviour of the resistivity. An orbital critical field as high as 300 T is extrapolated. Meissner flux expulsion up to 40% is observed. Small amounts of magnetic Cu2+ ions are correlated with the presence of the impurity phase BaCuO2. The Pauli susceptibility and the specific-heat jump at Tc are consistent with γ 2 mJ/(K2 gat) (9 mJ/(K2 mole-Cu)), neglecting all renormalizations.

49 citations

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29 citations