Structural and superconducting properties of R1−xCaxBa2Cu3O7−δ with 0.50>~x>~0.00

A. Sedky; Anurag Gupta; V. P. S. Awana; A. V. Narlikar

doi:10.1103/PhysRevB.58.12495

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Structural and superconducting properties of R1−xCaxBa2Cu3O7−δ with 0.50>~x>~0.00

A. Sedky, Anurag Gupta, V. P. S. Awana, A. V. Narlikar

DOI 10.1103/PhysRevB.58.12495 · Physical Review B

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Abstract

We report here a consolidated study of structural and superconducting properties of Ca substituted R1−xCaxBa2Cu3O7−δ system, with R=Er, Y, Sm, and Nd, and for 0.50>~x>~0.00. Interestingly, with increasing x, Er/Y samples show a behavior significantly different from Sm/Nd. In particular (1) orthorhombic distortion of R:123 lattice is found to be little affected for Er/Y samples with increasing x in comparison to Sm/Nd samples, (2) although Ca substitution leads to oxygen depletion for all the four sets of samples, the average Cu valence is, in general, found to remain invariant with x, (3) ρ(T) is found to show an upward curvature for Er/Y samples, which is absent for the Sm/Nd samples, and (4) Tc(ρ=0) as a function of x and δ shows a much steeper decrease in Er/Y based samples, than in Sm/Nd based ones. Our results unequivocally point to a different structural order or disorder in Er/Y samples as compared to Sm/Nd based samples. We suggest that different site preferences of oxygen vacancies, predominantly created in CuO2 planes (CuO chains) of Er and Y (Sm and Nd) based samples, might be responsible for the observed difference in the behavior. This contention is supported by a host of other considerations and experimental observations.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
ErBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	90	Pressure not reported	zero_resistance
Er0.9Ca0.1Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	78	Pressure not reported	zero_resistance
Er0.8Ca0.2Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	64	Pressure not reported	zero_resistance
Er0.7Ca0.3Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	54	Pressure not reported	zero_resistance
Er0.5Ca0.5Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	44	Pressure not reported	zero_resistance
YBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	90	Pressure not reported	zero_resistance
Y0.9Ca0.1Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	78	Pressure not reported	zero_resistance
Y0.8Ca0.2Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	67	Pressure not reported	zero_resistance
Y0.7Ca0.3Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	55	Pressure not reported	zero_resistance
Y0.5Ca0.5Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	46	Pressure not reported	zero_resistance
SmBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	89	Pressure not reported	zero_resistance
Sm0.9Ca0.1Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	79	Pressure not reported	zero_resistance
Sm0.8Ca0.2Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	73	Pressure not reported	zero_resistance
Sm0.7Ca0.3Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	68	Pressure not reported	zero_resistance
Sm0.5Ca0.5Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	64	Pressure not reported	zero_resistance
NdBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	88	Pressure not reported	zero_resistance
Nd0.9Ca0.1Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	82	Pressure not reported	zero_resistance
Nd0.8Ca0.2Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	74	Pressure not reported	zero_resistance
Nd0.7Ca0.3Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	71	Pressure not reported	zero_resistance
Nd0.5Ca0.5Ba2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	70	Pressure not reported	zero_resistance