Synthesis of the La3Ba5Cu8O18-δ and Sm3Ba5Cu8O18-δ superconductors by the combustion and solid-state reaction methods

Guerrero, U. Fuentes; Rivera, A.M. Morales; Cuaspud, J.A. Gómez; Munevar, J.; Vargas, C.A. Parra

doi:10.1590/1980-5373-MR-2020-0366

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Article • Mat. Res. 24 (1) • 2021 • https://doi.org/10.1590/1980-5373-MR-2020-0366 copy

Synthesis of the La₃Ba₅Cu₈O_18-δ and Sm₃Ba₅Cu₈O_18-δ superconductors by the combustion and solid-state reaction methods

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

In this paper, the synthesis of the La₃Ba₅Cu₈O_18-δ and Sm₃Ba₅Cu₈O_18-δ superconductors using the combustion method is reported for the first time. Besides, a comparison with the solid-state reaction method was performed. The materials were synthesized at 870 °C for 24 h under oxygen flow. Rietveld refinement showed materials with the main crystal phase corresponding to the orthorhombic structure of space-group Pmm2 (25), with purity in the range 51-85%, which had not reported for the RE358 systems. On the other hand, the magnetic measurements under external fields (30 and 100 Oe) confirmed the diamagnetic response associated with the Meissner effect, and T_c values between 24 and 58 K.

Keywords:
Superconductor; combustion; solid-state reaction

Method	Sample	χ²	R_f (%)	Phase	Phase proportion (%)	a (Å)	b (Å)	c (Å)	V (Å³)	r
Combustion	Sm358	1.249	0.109	Sm358	81.18	3.896(2)	3.876(7)	31.106(1)	469.8(2)	0.2509
	Sm358	1.249	0.109	Sm123	18.82	3.874(2)	3.874(2)	11.666(4)	175.1(2)
	La358	1.099	0.248	La358	50.81	3.918(2)	3.905(3)	31.293(8)	478.8(5)	0.1674
				La123	38.64	3.921(5)	3.921(5)	11.730(2)	180.3(7)
				BaCuO₂	10.54	18.318(8)	18.318(8)	18.318(8)	6147.3(6)
Solid-state reaction	Sm358	1.753	0.1407	Sm358	65.59	3.895(1)	3.865(8)	31.093(5)	468.2(3)	0.3775
				Sm123	34.29	3.894(9)	3.894(9)	11.717(4)	177.7(5)
				BaCuO₂	0.12	20.264(9)	20.264(9)	20.264(9)	8322.8(1)
	La358	1.835	0.2244	La358	85.35	3.906(3)	3.913(4)	31.374(5)	479.6(1)	0.0908
				La123	0.40	3.098(8)	3.098(8)	11.832(4)	113.6(3)
				BaCuO₂	14.25	18.300(1)	18.300(7)	18.300(1)	6128.4(9)

Atom	x	y	z	Occ	U
La(1)	0.5000	0.5000	1.0000	0.9900	0.025
Cu(1)	0.0000	0.0000	0.0625	1.0000	0.025
O(1)	0.0000	0.5000	0.0625	1.0000	0.025
O(2)	0.5000	0.0000	0.0625	1.0000	0.025
Ba(1)	0.5000	0.5000	0.1250	0.9900	0.025
O(3)	0.0000	0.0000	0.1250	1.0000	0.025
Cu(2)	0.0000	0.0000	0.1875	1.0000	0.025
O(4)	0.0000	0.5000	0.1875	0.9800	0.025
Ba(2)	0.5000	0.5000	0.2500	0.9900	0.025
O(5)	0.0000	0.0000	0.2500	0.9900	0.025
Cu(3)	0.0000	0.0000	0.3125	1.0000	0.025
O(6)	0.0000	0.5000	0.3125	0.9900	0.025
O(7)	0.5000	0.0000	0.3125	1.0000	0.025
La(2)	0.5000	0.5000	0.3750	1.0000	0.025
Cu(4)	0.0000	0.0000	0.4375	1.0000	0.025
O(8)	0.0000	0.5000	0.4375	0.9900	0.025
O(9)	0.5000	0.0000	0.4375	1.0000	0.025
La(3)	0.5000	0.5000	0.5000	1.0000	0.025
Cu(5)	0.0000	0.0000	0.5625	1.0000	0.025
O(10)	0.0000	0.5000	0.5625	1.0000	0.025
O(11)	0.5000	0.0000	0.5625	1.0000	0.025
Ba(3)	0.5000	0.5000	0.6250	0.9900	0.025
O(12)	0.0000	0.0000	0.6250	1.0000	0.025
Cu(6)	0.0000	0.0000	0.6875	1.0000	0.025
O(13)	0.0000	0.5000	0.6875	1.0000	0.025
Ba(4)	0.5000	0.5000	0.7500	0.9900	0.025
O(14)	0.0000	0.0000	0.7500	1.0000	0.025
Cu(7)	0.0000	0.0000	0.8125	1.0000	0.025
O(15)	0.0000	0.5000	0.8125	1.0000	0.025
Ba(5)	0.5000	0.5000	0.8750	0.9900	0.025
O(16)	0.0000	0.0000	0.8750	0.9900	0.025
O(17)	0.0000	0.5000	0.9375	0.9800	0.025
O(18)	0.5000	0.0000	0.9375	0.9900	0.025
Cu(8)	0.0000	0.0000	0.9375	1.0000	0.025

Method	H(Oe)	Sm₃Ba₅Cu₈O_18-δ		La₃Ba₅Cu₈O_18-δ
Method	H(Oe)	T_c (K)	T_irr (K)	T_c (K)	T_irr (K)
Solid-state reaction	30	43.30	31.99	39.73	38.03
Solid-state reaction	100	49.08	44.11	40.57	37.98

Combustion	30	56.59	43.15	23.99	14.41
	100	58.26	49.88	25.59	17.19

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