Thermoanalytical Studies on Preparation Conditions of Superconducting YBa₂Cu₃O_7-y

Abstract

We studied the decarbonation process of a ternary mixture of Y2O3, BaCO3 and CuO or Cu2O by TG-DTA analysis to clarify the optimum condition for the preparation of YBa2Cu3O7-y ceramics, which are superconducting above 90 K. We found that a narrow temperature region, 940∼950°C, is desirable for the decarbonation process. Furthermore, we observed an anomaly at ∼600°C in DTA curves of stoichiometric YBa2Cu3O7-y ceramics and nonstoichiometric Y–Ba–Cu–O samples. From the strong correlation between the magnitude of this anomaly and the composition of the ceramics, the anomaly was attributed to the orthorhombic-tetragonal phase transition in the YBa2Cu3O7-y phase. It was also found that the composition dependence of T c of the ceramics correlates strongly with that of the magnitude of the anomaly.

Rational Solid-State Synthesis Routes for Inorganic Materials

“…The chemistry that covers YBa 2 Cu 3 O 7 , or YBCO (MP: 20674), has been thoroughly studied in the literature due to the high-temperature superconducting properties of this class of cuprates. The common conventional routes for YBCO synthesis involve Y 2 O 3 , CuO (or Cu 2 O), and BaCO 3 (or BaO), − and are found to be Pareto optimal (R0, R1, and R3) in PIRO recommendations for the use of standard (i.e., elements, simple binary compounds, and carbonates of metals, excluding metal alloys) precursors (Figure a and Table ), none being any better than the others simultaneously on both nucleation and selectivity axes. A relatively higher barrier for a particular route such as R0 in comparison to other routes does not preclude it from nucleation (as every reaction shown already has favorable energy and hence is thermodynamically feasible), it simply implies that nucleation is likely to be relatively more difficult.…”

“…In Fig. 3(d [66][67][68] and are found to be Pareto optimal (R0, R1 and R3) in Figure 4: Route planning plots for synthesis of tetragonal YBa 2 Cu 3 O 7 under typical thermodynamic conditions using various sets of starting materials. Standard reactants include elements, stable binary compounds (excluding Y-Cu and Y-Ba alloys for simplicity) and carbonates.…”

Rational Solid-State Synthesis Routes for Inorganic Materials

“…In Fig. 3(d [66][67][68] and are found to be Pareto optimal (R0, R1 and R3) in PIRO recommendations for the use of standard (i.e. elements, simple binary compounds and carbonates of metals, excluding metal-alloys) precursors (Fig.…”

“…Case study: Superconducting YBa 2 of cuprates. The common conventional routes for YBCO synthesis involve Y 2 O 3 , CuO (or Cu 2 O) and BaCO 3 (or BaO),[66][67][68] and are found to be Pareto optimal (R0, R1 and R3) in…”

The YBCOPbS high-temperature superconducting system. Further investigations

“…The endotherms were observed in DTA at about 830 and 970°C which result from decomposition of BaCO, and partial melting of Y,Ba,Cu,O,-z, respectively. The TGA curve revealed approximately 0.5 mass% loss around 270 "C which may be attributed [15] to the expelled absorbed gases, moisture, etc. from the powder.…”