Enhancement and degradation of Tc in Bi-HTSC due to Li3+ irradiations
02 Jul 1999-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms (North-Holland)-Vol. 156, Iss: 1, pp 50-53
TL;DR: In this article, the superconducting critical temperature of Li-irradiation of O-rich Bi(2.2.1.2) with excess oxygen and O-content less than the optimum was investigated.
Abstract: Radiation damage in Bi2Sr2CaCu2O8+δ or Bi(2 2 1 2) by 55 MeV Li3+-beam has been studied from electrical resistivity and X-ray diffraction characterizations. This irradiation increases electrical resistivity and broadens X-ray diffraction lines by generating defects in all samples. But superconducting critical temperature, Tc, is seen to increase for Bi(2 2 1 2) with excess oxygen and decrease for Bi(2 2 1 2) with O-content less than the optimum, that gives maximum Tc. This increase of the superconducting critical temperature on Li-irradiation of O-rich Bi(2 2 1 2) as well as the decrease for low-O Bi(2 2 1 2) is due to O-displacement. This is in agreement with our earlier He-irradiation results.
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TL;DR: In this paper, a brief account of the evolution of defects due to controlled changes in polycrystalline zinc oxide has been presented and a coherent scenario in the light of previous works in this field has been discussed.
289 citations
01 Dec 2003-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, a highly resistive nanocrystalline thin film of Li0.25Mg0.5Mn0.1Fe2.15O4, deposited by RF magnetron sputtering technique on Si(1/0/0) substrate, is irradiated with 190 MeV Au14+ ions.
Abstract: A highly resistive nanocrystalline thin film of Li0.25Mg0.5Mn0.1Fe2.15O4, deposited by RF magnetron sputtering technique on Si(1 0 0) substrate, is irradiated with 190 MeV Au14+ ions. To probe the swift heavy ion induced modifications in the electrical properties in the film an in situ measurement of electrical resistance using two-probe method is carried out. We observe the value of resistivity comes down drastically from 1.5 × 108 to 1 × 105 Ω cm after irradiation at the fluence of 1 × 1013 ions/cm2. In XRD spectra after irradiation no previous spinel peaks are observed. No loss in oxygen content with fluence is observed. We have presented the observed phenomenon as an effect of formation of amorphized latent tracks on the basis of thermal spike model.
21 citations
01 Sep 2004-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, a transformation from ferrimagnetic to superparamagnetic behavior is observed from CEMS (conversion electron Mossbauer spectroscopy) with increase in fluence from 2.5×-1012 to 1.3x-1013 ions/cm2.
Abstract: Nanocrystalline Li0.25Mg0.5Mn0.1Fe2.15O4 ferrite thin films, prepared by R.F. magnetron sputtering technique, are irradiated with 190 MeV Au14+ ions. The significant behavioural changes in magnetic and electrical properties of thin films after swift heavy ion irradiation confirm the formation of stable defects. A transformation from ferrimagnetic to superparamagnetic behaviour is observed from CEMS (conversion electron Mossbauer spectroscopy) with increase in fluence from 2.5 × 1012 to 1 × 1013 ions/cm2. The resistivity initially increases after irradiation till the fluence reaches 1 × 1012 ions/cm2 and then reduces with further increase in fluence. We have also studied the X-ray diffraction pattern with fluence variation. A possible explanation of the above results on the basis of thermal spike model is presented. These effects are mainly due to amorphized latent tracks and variation in the cation distribution due to heavy ion irradiation.
13 citations
TL;DR: In this paper, the effect of irradiation on superconducting microregions was studied in (Bi 0.92 Pb 0.17 )-2212 and (Bi,Pb) 0.14×10 15 He ++ /cm 2 samples.
Abstract: Radiation damage in Bi-2212 and (Bi 0.92 Pb 0.17 )-2212 superconducting pellets due to irradiation by 40 MeV He ++ -beam has been studied, as these two compounds differ with respect to lattice strain in their Bi–O and (Bi,Pb)–O layers. These samples were prepared with excess oxygen that accounts for their lowered superconducting transition temperature, T c , of 59.5 and 64.5 K, respectively. Irradiation to 8.14×10 15 He ++ /cm 2 raised T c by 4.5 and 5.5 K, respectively, and also their normal state resistivities. Excess conductivity analysis for the unirradiated and irradiated samples showed (i) a transition of the conductivity fluctuation from 2D ( λ =1.0) to 3D ( λ =0.5) behaviour, on cooling across a temperature T 0 , and (ii) also the signature ( λ =3.0) of critical fluctuations in a network of superconducting microregions, for temperatures below T cr , where T cr is seen to be 5 to 10 K lower than T 0 . The rise in T c has been explained from irradiation-induced removal of oxygen taking the hole concentration towards the value for the peak in T c .
8 citations
01 Mar 2006-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the effect of disorder on Bi-2212 type high Tc superconducting and LCMO type CMR oxide materials has been investigated and results have been discussed in the light of their intrinsic granular nature.
Abstract: Present report deals with the effect of disorder on Bi-2212 type high Tc superconducting and LCMO type CMR oxide materials. Ion irradiation (50 MeV Li3+ beam) creates high level of disorder in the superconducting system and as a result increase of room temperature resistivity (ρ300) has been observed. Radiation induced point defects cause an increased dρ/dT in the metal-like regime of Bi-2212. Similar increase of dρ/dT in the FM (ferromagnetic and metal-like) state has also been found in LCMO system. Enhancement of metal-like behavior is unusual in the sense that a simultaneous decrease of Tmi (metal–insulator transition temperature for LCMO) or Tc (superconducting transition temperature for Bi-2212) due to irradiation has also been observed. Effect of the defects incorporated by other means like variation of heat treatment and ion irradiation has been investigated for a better understanding on the electrical transport in these complex materials. Results have been discussed in the light of their intrinsic granular nature.
4 citations
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TL;DR: In this paper, the static magnetic susceptibility of hole-doped oxide superconductors was studied as a function of oxygen content over the temperature range 2-900 K, and a correlation was observed between the magnitude of T c ( y ) and the temperature dependence of the normal-state magnetic susceptibility.
Abstract: The static magnetic susceptibility of Bi 2 Sr 2 CaCu 2 O 8+ y and Tl 2 Ba 2 CuO 6+ y is studied as a function of oxygen content y over the temperature range 2–900 K. With increasing oxygen (hole) content the superconducting transition temperature T c ( y ) passes through a maximum for the Bi-compound and falls monotonically for the Tl-system, reaching a maximal value of c ≅92 K in both systems. As the oxygen content is varied, a correlation is observed between the magnitude of T c ( y ) and the temperature dependence of the normal-state magnetic susceptibility. The fact that this same correlation can also be seen in the published data on La 2- x Sr x CuO 4 and YBa 2 Cu 2 O 6+ y implies that it may be a universal property of hole-doped oxide superconductors.
82 citations
TL;DR: In this article, Tl-based superconducting copper oxides were irradiated at 140 K by 3.6 GeV Xe ions and the resistance measured in situ as a function of the fluence.
Abstract: Tl-based superconducting copper oxides Tl 2 Ba 2 CaCu 2 O 8 , TlBa 2 Ca 2 Cu 3 O 9 and Tl 2 Ba 2 Ca 2 Cu 3 O 10 were irradiated at 140 K by 3.6 GeV Xe ions and the resistance measured in situ as a function of the fluence. The results confirm that electronic stopping of GeV heavy ions plays a major role in the defect creation mechanism. Critical current densities were obtained from magnetization measurements on samples irradiated by 5.8 GeV Xe ions at fluences up to 2x10 12 cm -2 and magnetic field orientations parallel and normal to the heavy ions tracks. Large enhancements of flux pinning and J c are observed, in particular at low fluences, without significant change of the T c 's.
36 citations
TL;DR: A substantial increase in the transition temperature has been noted in Bi 2 Sr 2 CaCu 2 O x superconductor after irradiation with 20 MeV alpha particles as mentioned in this paper, probably due to oxygen removal from an oxygen rich superconducting phase.
15 citations
TL;DR: Positron annihilation lifetime (PAL) measurements on well-characterized pellets of Bi-2212, (Bi,Pb)-2212 and Bi-Pb-2223 superconductors indicate the presence of a very long (around 1500 ps) third lifetime.
14 citations