Energy dependent structure of Xe ion tracks in YBCO and the effect on the superconductive properties in magnetic fields

Abstract

The morphology and structure of damaged regions (tracks) produced by swift heavy 167, 77 and 46 MeV 132 Xe 23+ ions in YBCO-based second generation industrial high temperature superconductors wires (2G HTS) were studied using transmission electron microscopy. It was shown that ion produce tracks aligned along the ion trajectory but of morphology depending on their energy: continuous, nearly continuous or discontinuous tracks like prolate ellipsoids 10-15 nm in length and spheroids 5 nm in diameter. The damaged regions of about 5 nm in diameter contain an amorphous material with a lower density compared to pristine YBCO. The material density drops from 6300 kgm-3 for YBCO matrix to 3600 kgm-3 inside the tracks. Barium enrichment was found in the vicinity of the track at a distance of about 10 nm from the center of the defect. Ion damage tracks with different morphology showed different effectiveness as pinning centers. Tracks composed of discontinuous pinning centersspheroids of about 5 nm in diameterbring the best enhancement of the critical current density. It occurs for the lowest ion energy (46 MeV) in the range of energy loss 8.9 keV/nm-4.7 keV/nm for Xe ions. The samples showed highest critical current density of 56 MA/cm 2 (4.2K) and 3 MA/cm 2 (77K) in self-field while in magnetic fields of 8T the values of 17 MA/cm 2 (4.2K) and 1.6 MA/cm 2 (77K) were achieved. The reduction of the superconducting volume corresponding to the amorphous radiation defects did not exceed 4% from the total sample volume.

Enhancement of self-field critical current density by several-tens-MeV ion irradiation in YBa2Cu3O7 films prepared by fluorine-free metal-organic deposition

“…These lines are consistent with our SRIM calculation 30) that the electronic stopping power (S e ) of 66 MeV Au ions decreases by only about 22% (from 16.7 to 13.1 keV nm −1 ) within a 1 μm thick YBCO film. According to previous TEM results, 23) amorphous ion tracks are formed in YBCO when S e exceeds 4.7 keV nm −1 .…”

“…A similar elongation was previously observed in YBCO films irradiated with 46 and 77 MeV Xe ions. 23) Factor (ii) above is related to the empirical rule from previous in-magnetic-field-J c studies; namely, a higher dose is required to enhance pinning with lower-E i ion irradiation. 24) The optimal dose for 24 and 44 MeV irradiation in terms of pinning efficiency might be higher than that for 66 MeV (1 × 10 11 cm −2 ) to locate in the range where T c already degraded (>1 × 10 12 cm −2 ).…”

Влияние Радиационных Дефектов Различного Типа На Критический Ток Слоистого Анизотропного Сверхпроводника

“…Дополнительно к собственным центрам пиннинга образец может содержать искусственные радиационные дефекты. В нашей работе мы исследуем влияние на вихревую решетку дефектов, возникающих при облучении сверхпроводника электронами и ионами различной энергии, для определенности, ионами ксенона [39]. Конфигурации дефектов, возникающих при этом, показаны схематично на рис.…”

Увеличение Критического Тока Сверхпроводящих Композитов При Имплантации Ионов Железа

“…Исследование воздействия облучения тяжелыми ионами инертных газов [44,45] показывают некоторый рост критического тока при низких флюенсах с последующим монотонным снижением вплоть до полного исчезновения сверхпроводящих свойств уже при флюенсе ∼ 10 13 cm −2 . Как показывают исследования, радиационная стойкость ВТСП-лент по отношению к облучению 132 Xe 27+ (167 MeV), 132 Xe 27+ (80 MeV) и 84 Kr 17+ (107 MeV) составляет 1 • 10 12 cm −2 , 3.5 • 10 13 cm −2 и 1 • 10 13 cm −2 соответственно [46]. Также были проведены исследования с применением ионов кислорода [47][48][49], циркония [50], свинца [51].…”