DOI: 10.18150/ifaz9s
title: High-pressure growth effects on the superconducting properties of Sm-based oxypnictide superconductors

description: Experimental data collected for the preparation of the manuscript: "High-pressure growth effects on the superconducting properties of Sm-based oxypnictide superconductors"Title: High-pressure growth effects on the superconducting properties of Sm-based oxypnictide superconductorsAuthors: Mohammad Azam, Manasa Manasa, Tatiana Zajarniuk, Ryszard Diduszko, Taras Palasyuk, Tomasz Cetner, Andrzej Morawski, Cezariusz Jastrzębski, Andrzej Szewczyk, Michał Wierzbicki, Shiv J. SinghCeramics International 51 (2025) 13734–13751Abstract:High-pressure synthesis can be an effective method for improving the sample quality of materials as well as their superconducting properties. In this paper, the synthesis process of F-doped SmFeAsO has been optimized by preparing a series of bulk SmFeAsO0.8F0.2 (Sm1111) using the high gas pressure and high-temperature synthesis (HP-HTS) method, considering various growth parameters like growth pressures (0–1 GPa) and heating time (0.5–2 h) at the low synthesis temperature of 900 oC. Structural, microstructural, Raman spectroscopic, transport, and magnetic measurements are employed to comprehensively analyze these bulks and derive the conclusive findings. The parent SmFeAsO0.8F0.2 prepared by the conventional synthesis process at ambient pressure (CSP) has a transition temperature (Tc) of around 53–54 K, and the critical current density (Jc) of 103 A/cm2 at 5 K with a small amount of the impurity phases (SmOF and SmAs), consistent with previous reports. Interestingly, all bulks synthesized by HP-HTS have almost the same Tc and Jc as the parent sample. The optimal growth conditions are obtained as 900◦C, 1 h, and 0.5 GPa with the sealed Ta-tube, which slightly improved the sample quality and the superconducting properties compared to other bulks grown by HP-HTS. Our study confirms that the existence of the impurity phases in the 1111 family is very robust and cannot be reduced by HPHTS, leading to only a small variation in the observed superconducting properties of Sm1111 whether prepared by CSP or HP-HTS. This is the first comprehensive investigation of the high-pressure development of Sm1111, which shows distinct behaviour from other families of iron-based superconductors.Note: In the published article,Figure 1 is the block diagram of the preparation conditions. (No dataset for this figure)Figure 6 is the scanning electron microscope (SEM) image of SmFeAsO0.80F0.20, samples prepared under different conditions. (No dataset for this figure)Fig. 1. The preparation conditions of three distinct batch SmFeAsO0.8F0.2 samples using the HP-HTS technique under varying conditions are depicted. These batches are defined by considering the ground and direct pellet of the parent sample P. (No dataset for this figure)Fig. 2. (a) X-ray diffraction patterns (XRD) of powder SmFeAsO0.8F0.2 sample (P) prepared by CSP at ambient pressure, ground, and pelletized samples G0, G1, G2, G3, and G4 prepared by HP-HTS at constant heating temperature 900◦C and time 1 h under different growth pressures of 0, 0.3, 0.5, 0.7 and 1 GPa. (b) An enlarged view of the main peak (102) position is depicted. The variation of (c) lattice parameter (a), (d) lattice parameter (c), and (e) unit cell volume (V) with the various synthesis pressures (0–1 GPa) for the sample G0, G1, G2, G3, and G4.Fig. 3. (a) X-ray diffraction patterns (XRD) of powder SmFeAsO0.8F0.2 sample of the parent P prepared by CSP at ambient pressure, and direct pellet samples D0, D1, and D2 prepared by HP-HTS at constant temperature 900◦C and time 1 h under different growth pressure of 0 GPa, 0.5 GPa, and 1 GPa. (b) An enlarged view of the main peak (102) position is depicted. The variation of (c) lattice parameter (a), (d) lattice parameter (c), and (e) unit cell volume (V) with the various pressures (0–1 GPa) for the sample D0, D1, and D2.Fig. 4. (a) X-ray diffraction patterns (XRD) of powder SmFeAsO0.8F0.2 parent P sample prepared by CSP at ambient pressure, and ground and pelletized samples T1, T2, and T3 prepared by HP-HTS at constant temperature 900◦C and the growth pressure of 0.5 GPa under different heating time of 0.5, 1 and 2 h. (b) An enlarged view of the main peak (102) position is depicted. The variation of (c) lattice parameter (a), (d) lattice parameter (c), and (e) lattice volume (V) with the various growth time (0.30–2 h) for the sample T1, T2, and T3.Fig. 5. (a) Raman scattering spectrum acquired for the “G” batch is shown, and major spectral features are present in spectra obtained under different synthesis pressures. Experimental spectrum (open circles) is fitted by peaks of Lorentzian line shape (solid lines). (b), (c), (d) Variation of peak positions measured for samples from “G”, “D” and “T” batches.Fig. 7. (a) The variation of resistivity (ρ) with the temperature up to the room temperature (b) Low-temperature variation of the resistivity up to 60 K for the parent P sample synthesized under various pressure 0–1 GPa prepared by HPHTS method, and ground and pelletized samples: G0: 0 GPa, G1: 0.3 GPa, G2: 0.5 GPa and G3: 0.7 GPa and G4: 1 GPa.Fig. 8. (a) The variation of resistivity (ρ) with the temperature up to the room temperature (b) Low-temperature variation of the resistivity up to 60 K for the parent P sample, and direct pellet samples D0: 0 GPa, D1: 0.5 GPa, D2: 1 GPa prepared by HP-HTS.Fig. 9. (a) The variation of resistivity (ρ) with the temperature up to the room temperature (b) Low-temperature variation of the resistivity up to 60 K for the parent P sample, and ground and pelletized parent samples for different heating times T1 for 0.5 h, T2 for 1 h and T2 for 2 h, prepared by HP-HTS at constant temperature 900 ◦C and growth pressure of 0.5 GP.Fig. 10. The temperature dependence of the normalized magnetic moment in ZFC and FC mode at the magnetic field of 20 Oe for (a) the parent P sample, and ground and pelletized samples: G2: 0.5 GPa and G4: 1 GPa with Parent P sample (b) the parent P sample, and direct pellet samples D0: 0 GPa, D1: 0.5 GPa, D2: 1 GPa (c) the parent P sample, and ground and pelletized parent samples for different heating times T1 for 0.5 h, T2 for 1 h and T2 for 2 h prepared by HP-HTS.Fig. 11. The variation of the critical current density (Jc) at 5 K with the applied magnetic field up to 9 T (a) for the parent sample, G2 and G4 at 5 K (b) for parent P, D1, D2 (c) for parent P, T2 and T3. The inset shows the magnetic hysteresis loop (M–H) for P, G2 and G4 in Figure (a), P, D1 D2 in Figure (b) and P, T2, T3 in Figure (c).Fig. 12. The variation of (a) the onset transition temperature (Tconset) (b) the transition width (ΔT), (c) room temperature resistivity (ρ300 K) (d) RRR (= ρ300K/ρ60 K), (e) critical current density (Jc) of SmFeAsO0.8F0.2 with the various growth pressure for the parent P and G-batch: G0: 0 GPa, G1: 0.3 GPa, G2: 0.5 GPa and G3: 0.7 GPa and G4: 1 GPa prepared by HP-HTS.Fig. 13. The variation of (a) the onset transition temperature (Tconset) (b) thetransition width (ΔT), (c) room temperature resistivity ρ300 K (d) RRR (= ρ300 K / ρ60 K), (e) critical current density (Jc) of SmFeAsO0.8F0.2 with the various growth pressure for the parent P and D-batch samples. D0, D1, and D2 are prepared by HP-HTS at constant temperature 900 ◦C and time 1 h under different growth pressure of 0, 0.5, and 1 GPa.Fig. 14. The variation of (a) the onset transition temperature (Tconset) (b) the transition width (ΔT), (c) room temperature resistivity ρ300 K (d) RRR (= ρ300 K/ρ60 K), (e) critical current density (Jc) of SmFeAsO0.8F0.2 with the various growth pressure for the parent P and T-batch samples. T1, T2, and T3 are prepared by HP-HTS at constant temperature 900◦C and the growth pressure of 0.5 GPa under different heating temperature of 0.5, 1 and 2 h, respectively.Fig. 15. The variation of (a) the onset transition temperature (Tconset) (b) the critical current density Jc values of various Sm1111 bulk samples prepared by HP-HTS with the growth pressure. The Jc dependence of (c) the superconducting Sm1111 phase (%) obtained from XRD and (d) the sample density for some selected G, D and T-batch samples.