TY - JOUR
T1 - Oxygen annealing and the related thermodynamics in HgBa2CuO4+δ
AU - Xiong, Q.
AU - Xue, Y. Y.
AU - Chen, F.
AU - Cao, Y.
AU - Sun, Y. Y.
AU - Liu, L. M.
AU - Jacobson, A. J.
AU - Chu, C. W.
N1 - Funding Information:
The authortsh ankQ . Huanga ndJ. Lynn for NPD data,H . Changa ndY.T. Ren for Ramand ata.T his work is supporteidn partb y USAFOSR F49620-93-1-0310b y BMDO, NSF GrantN o. NMR 91-22043, ARPA Grant No. MDA 972-90-J-1001th, eS tateo f Texast hroughth eT exasC enterfo r Superconductivity at theU niversityo fH oustona, ndt heT .L.L. Temple and R.A. WelchF oundations.
PY - 1994/10/1
Y1 - 1994/10/1
N2 - Several well-characterized HgBa2CuO4+δ samples were annealed under various conditions. Above 300°C and at various oxygen partial pressures, both reversible oxygen intake/release and irreversible Hg-loss take place with different time constants. By choosing the proper annealing temperature Ta, oxygen pressure P(O2) and annealing time t, the Hg-loss effects were negligible and the bulk superconducting transition temperature Tc was reversibly changed with δ from 0 K on the underdoped side (an insulator) through a peak of 97 K, then down to ∼ 20 K on the overdoped side. The measured 3D variation of Tc vs. (1/Ta, ln P(O2)) appears as a parabolic surface with iso-Tc segments projected on a 2D 1/Ta-ln P(O2) plane as straight lines. The slope [∂ ln P(O2)/∂(1/Ta)]Tc of the projections corresponds to the oxidation enthalpy ΔH, and the derivative (∂ ln P(O2)/∂Tc)Ta which is a measure of the Tc variation with the oxygen partial pressure used in the annealing, is related to the defect-interactions and the Tc-δ correlation. The data for YBa2Cu3O7-δ, Bi2Sr2CaCu2O8+δ, and HgBa2CuO4+δ are compared.
AB - Several well-characterized HgBa2CuO4+δ samples were annealed under various conditions. Above 300°C and at various oxygen partial pressures, both reversible oxygen intake/release and irreversible Hg-loss take place with different time constants. By choosing the proper annealing temperature Ta, oxygen pressure P(O2) and annealing time t, the Hg-loss effects were negligible and the bulk superconducting transition temperature Tc was reversibly changed with δ from 0 K on the underdoped side (an insulator) through a peak of 97 K, then down to ∼ 20 K on the overdoped side. The measured 3D variation of Tc vs. (1/Ta, ln P(O2)) appears as a parabolic surface with iso-Tc segments projected on a 2D 1/Ta-ln P(O2) plane as straight lines. The slope [∂ ln P(O2)/∂(1/Ta)]Tc of the projections corresponds to the oxidation enthalpy ΔH, and the derivative (∂ ln P(O2)/∂Tc)Ta which is a measure of the Tc variation with the oxygen partial pressure used in the annealing, is related to the defect-interactions and the Tc-δ correlation. The data for YBa2Cu3O7-δ, Bi2Sr2CaCu2O8+δ, and HgBa2CuO4+δ are compared.
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U2 - 10.1016/0921-4534(94)90627-0
DO - 10.1016/0921-4534(94)90627-0
M3 - Article
AN - SCOPUS:0028517310
SN - 0921-4534
VL - 231
SP - 233
EP - 242
JO - Physica C: Superconductivity and its applications
JF - Physica C: Superconductivity and its applications
IS - 3-4
ER -