Preparation and properties of superconducting La1+xBa2−xCu3Oy (0≤x≤0.5) ceramics sintered in N2 gas atmosphere

Takahiro Wada; Nobuo Suzuki; Atsutaka Maeda; Tomoaki Yabe; Kunimitsu Uchinokura; Shin-ichi Uchida; Shoji Tanaka

doi:10.1103/PhysRevB.39.9126

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Preparation and properties of superconducting La1+xBa2−xCu3Oy (0≤x≤0.5) ceramics sintered in N2 gas atmosphere

Takahiro Wada, Nobuo Suzuki, Atsutaka Maeda, Tomoaki Yabe, Kunimitsu Uchinokura, Shin-ichi Uchida, Shoji Tanaka

DOI 10.1103/PhysRevB.39.9126 · Physical Review B

T1

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Abstract

A study of the preparation and properties of La1+xBa2−xCu3Oy (0≤x≤0.5) system was performed on two kinds of samples. One with 0≤x≤0.2 was sintered at 970–980 °C in N2 gas and postannealed at 300 °C in O2 gas atmosphere and the other with 0≤x≤0.5 was sintered at 900 °C in N2 gas and postannealed under the same conditions. The samples sintered at 970–980 °C were orthorhombic and their oxygen content(y) was nearly 6.95, smaller than that of those sintered at 900 °C, which was about 7.15. Thermogravimetric study revealed that samples sintered at 900 °C contained a large amount of oxygen; the oxygen content was not substantially reduced at elevated temperature, even in N2 gas atmosphere. Resistivity and dc magnetic-susceptibility-measurements revealed that the superconducting properties of the samples sintered at 970–980 °C were much better than those of the samples sintered at lower temperature. The Tc’s in the La1+xBa2−xCu3Oy system with y≊7.0 decreased linearly from 93 to 80 K with excess La content, x. Differential scanning calorimetry in O2 gas atmosphere showed that the orthorhombic-tetragonal structural phase transition temperatures were lowered monotonically from 485 °C (x=0) to 443 °C (x=0.3). We address the effect of La substitution for Ba in LaBa2Cu3O7.0 samples on their superconducting properties. We discuss the relation between the oxygen content in La1+xBa2−xCu3Oy samples and their superconducting properties. Finally, we discuss the reasons why the superconducting properties of the samples which were sintered in N2 gas are better than those of the samples sintered in O2 gas or air.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
LaBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	93	Pressure not reported	onset
LaBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	92	Pressure not reported	zero_resistance
LaBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	93	Pressure not reported	unknown
La1.05Ba1.95Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	91	Pressure not reported	unknown
La1.1Ba1.9Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	86	Pressure not reported	unknown
La1.2Ba1.8Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	79	Pressure not reported	unknown
La1.3Ba1.7Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	70	Pressure not reported	unknown
LaBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	90	Pressure not reported	unknown
La1.05Ba1.95Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	88	Pressure not reported	unknown
La1.1Ba1.9Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	79	Pressure not reported	unknown
La1.2Ba1.8Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	60	Pressure not reported	unknown
La1.3Ba1.7Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	50	Pressure not reported	unknown
La1.4Ba1.6Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	50	Pressure not reported	unknown
La1.1Ba1.9Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	84	Pressure not reported	unknown
La1.1Ba1.9Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	74	Pressure not reported	unknown