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Journal ArticleDOI

Specific heat of praseodymium doped yttrium barium copper oxide

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.
About: This article is published in Solid State Communications.The article was published on 1988-07-01. It has received 17 citations till now. The article focuses on the topics: Schottky anomaly & Calorimeter.
Citations
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TL;DR: The properties of the Y1−xPrxBa2Cu3O7 (YPrBCO) system are reviewed in this paper, including superconducting, normal state, structural, chemical, optical, magnetic, and thermal properties.
Abstract: The properties of the Y1−xPrxBa2Cu3O7 (YPrBCO) system are reviewed. These include superconducting, normal state, structural, chemical, optical, magnetic, and thermal properties. The destruction of superconductivity with Pr doping is discussed in view of possible models such as hole filling, localization, magnetic pair-breaking, and the role of hybridization. Applications to electronic devices using YBCO/PrBCO/YBCO multilayers are also reviewed.

327 citations

Journal ArticleDOI
TL;DR: In this article, the crystal structure, superconductivity and magnetic properties of the title compounds have been investigated and the results revealed that with the concentration of Pr being constant, the transition temperatureTc of this system decreases with the increasing of La, or rather with an increasing of effective ionic radii of rare earth elements and disappears at aboutx=0.6.
Abstract: The crystal structure, superconductivity and magnetic properties of the title compounds have been investigated. The results revealed that with the concentration of Pr being constant, the transition temperatureTc of this system decreases with the increasing of La, or rather with the increasing of effective ionic radii of rare earth elements and the superconductivity disappears at aboutx=0.6. The coefficient of electron specific heat and the density statesN (0) which were infered from the magnetic measurements also decrease with the increasing of the effective radii. The relation between the radii of rare earth elements and hybridization is briefly discussed.

134 citations

Journal ArticleDOI
TL;DR: The crystallographic changes that occur with increasing Pr concentration in the Y−xPrxBa2Cu3O7−δ system have been studied by neutron diffraction as discussed by the authors.
Abstract: The crystallographic changes that occur with increasing Pr concentration in the Y−xPrxBa2Cu3O7−δ system have been studied by neutron diffraction. As x is increased from 0 to 1, the orthorhombic a, b and c lattice parameters expand monotonically, while the orthorhombic distortion, espressed as b a , decreases, reflecting increased occupation of O(5) sites at the expense of O(4) chain site occupancy. The separation of the CuO2 planes in PrBa2Cu3O7−δ indicates that the Pr ions have an intermediate valence of ∼3.3 in this compound. Evidence is presented for increased interaction between the Pr ions and oxygen ions in adjacent CuO2 planes.

106 citations

Journal ArticleDOI
TL;DR: In this article, specific heat measurements on La2CuO4, La2−xMxCuO 4 (M = Ca, Sr, and Ba), YBa2Cu3O7, and the Bi-CaSr-Cu-O and Tl-Ca-Ba-cu-O systems are presented.
Abstract: We review the specific heat measurements on La2CuO4, La2−xMxCuO4 (M = Ca, Sr, and Ba), YBa2Cu3O7, and the Bi-Ca-Sr-Cu-O and Tl-Ca-Ba-Cu-O systems. Tables of properties derived from the data are presented. Results on RBa2Cu3O7 (R=rare earth elements other than Y) are summarized, as are results on YBa2(Cu3−xMx)O7 (M=Zn, Cr, Fe, or Ni). The difficulties of analyzing the specific heat data, and specifically the separation of the contributions associated with magnetic impurities, are discussed. It is tentatively concluded that the data nearT c are consistent with BCS theory, although they show evidence of fluctuation effects. It is also concluded that the low-temperature zero-field data on a majority of the high-T c oxide superconductors provide evidence of anintrinsic term that is proportional toT, a result that is inconsistent with a gap in the electronic density of states.

76 citations

Journal ArticleDOI
TL;DR: In this article, the superconducting behavior of oxides was investigated by resistivity and AC susceptibility measurements, and it was shown that the transition temperature (T c ) increases monotonically with x for x ≥ 0.6.
Abstract: The results of our investigation on the superconducting behaviour of the oxides Pr 1− x Gd x Ba 2 Cu 3 O y by resistivity and AC susceptibility measurements suggest that the superconducting transition temperature ( T c ) increases monotonically with x for x ≥0.6. The concentration of Pr required to depress T c in this Gd series appears to be smaller than in the corresponding Y series, possibly due to volume dependent hole trapping effects. Specific heat measurements were performed in the temperature range 0.4–20 K in order to understand the magnetism of the rare-earth ions. Interestingly, Pr and Gd ions undergo magnetic ordering independently though both are presumably present in the same magnetic sub-lattice and the observed ordering temperatures rule out any direct intersite Pr-Gd magnetic interaction in this series of compounds.

27 citations

References
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Journal ArticleDOI
01 Aug 1987-Nature
TL;DR: In this paper, the authors present the results of a study of the structure and transport properties of the series of compounds Y1−xPrxBa2Cu3O7−δ (x = 0−1.0), in which they observe a monotonic decrease in Tc and eventually a metal-nsulator transition with increasing Pr concentration.
Abstract: Considerable excitement has been generated by the report of superconductivity above 90 K in a multi-phase Y–Ba–Cu oxide1. The superconducting phase was subsequently identified as YBa2Cu3O7−δ2,3. The complete replacement of Y by the trivalent rare-earths La–Lu, with the exception of Ce, Pr and Tb, yields a superconducting phase with a critical temperature (Tc) almost identical to that reported for the yttrium compound4–7. This is somewhat surprising as most of these ions carry significant magnetic moments, the presence of which rapidly decreases Tc in ordinary superconductors. The three exceptions noted, Ce, Pr and Tb, are the rare-earth ions which have a stable tetravalent state. Here we present the results of a study of the structure and transport properties of the series of compounds Y1−xPrxBa2Cu3O7−δ (x = 0−1.0), in which we observe a monotonic decrease in Tc and eventually a metal–nsulator transition with increasing Pr concentration. To date, this is the only rare-earth ion which has been found substantially to alter Tc upon partial substitution for Y.

406 citations

Journal ArticleDOI
TL;DR: In this article, the superconducting and normal state properties of compounds in the series Y1−xMxBa2Cu3O7−δ for 0 ≤ × ≤ 1 and Y 1−x MxBa 2Cu 3O7 −δ in the limited region of solubility 0 ≤ ≤ ≤ 0.5 have been investigated by means of X-ray diffraction, electrical resistivity ϱ, and magnetic susceptibility χ measurements.

247 citations

Journal ArticleDOI
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

Journal ArticleDOI
Jingkui Liang1, X. T. Xu1, Sishen Xie1, G. H. Rao1, X. Y. Shao1, Z. G. Duan1 
TL;DR: In this paper, a series of Ba2(Y1−xPrCu3O9−y ) solid solutions with the orthorhombic distorted perovskite structure were prepared with the O(Y) structure.
Abstract: A series of Ba2(Y1−x Pr x )Cu3O9−y solid solutions were prepared with the orthorhombic distorted perovskite structure. The compound Ba2PrCu3O9−y belonging to tetragonal system is a good semiconductor. The superconductivity is observed for samples withx<0.6. With the increase of Y content, the distortion of crystal structure is greater and the superconductive transition temperature of zero resistanceTc(0) raises.

86 citations

Journal ArticleDOI
01 Dec 1987-Nature
TL;DR: In this article, the authors present high-resolution specific heat measurements on four different samples of YBa2Cu3O7−δ (YBCO) which reveal a new anomaly at 220 K. The strength of the anomaly as measured by its height is related to the size of the jump at the superconducting transition at 90 K.
Abstract: Extraordinary efforts have recently been put into trying to understand the new class of high-temperature superconducting copper oxides discovered by Bednorz and Muller1. Here, we present high-resolution specific heat measurements on four different samples of YBa2Cu3O7–δ (YBCO) which reveal a new anomaly at 220 K (see also ref. 2). The strength of the anomaly as measured by its height is related to the size of the jump at the superconducting transition at 90 K. Specific heat measurements are sensitive and reliable volume probes of ordering phenomena in the bulk of solids; our results therefore establish that there are ordering phenomena taking place in YBCO at ∼220 K. These findings may be of importance for understanding reports of oxygen ordering3–5 and of various unstable superconducting transitions in the range from 150 K (ref. 6) to well above 200 K (ref. 7).

86 citations