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  • 1
    Electronic Resource
    Electronic Resource
    Enhanced flux pinning from CuO inclusions in Bi2Sr2CaCu2Oy crystals (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 533-535 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bi2Sr2CaCu2Oy (Bi2212) crystals with CuO inclusions were grown on the surface of KCl flux. The density of CuO incorporations of 109/cm2 was similar to that for Y2BaCuOy in melt-textured YBa2Cu3Oy. The CuO inclusions are needlelike particles with diameter of less than 1 μm. Magnetization measurements show enhanced flux pinning at high magnetic field, compared to crystals without CuO. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364093
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  • 2
    Electronic Resource
    Electronic Resource
    Anisotropy of the critical current in silver sheathed (Bi,Pb)2Sr2Ca2Cu3O10 tapes (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1123-1130 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transport critical current of Bi:2223 tapes was measured in magnetic fields up to 15 T and at temperatures from 4.2 to 84 K. At high temperatures, the critical current density Jc is strongly anisotropic and the anisotropy increases rapidly with magnetic field, whereas at low temperatures the critical current is less anisotropic and the anisotropy is field independent above 1 T. In the former case we believe we are in a regime, where pinning limits Jc, at least within some parts of the tape, whereas in the latter case the limitation of Jc by Josephson weak links seems to be the dominant mechanism. In addition, a critical current hysteresis induced by flux trapping in a weak link network is observed, which is more pronounced at low temperatures. From transmission electron microscopy observations of the microstructure we find that the "brick'' in the "brick wall'' model turns out to be the colony instead of the grain inside the colony. Additionally it is found that colony boundaries parallel the ab plane and intersected boundaries occur much more frequently than boundaries parallel to the c axis, due to the misalignment of the colonies inside the tape. In a small region near the silver sheath colony misalignment is much smaller and boundaries parallel to the c axis may act as strong links at high temperatures as their interfaces are very clean and well matched. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360346
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  • 3
    Electronic Resource
    Electronic Resource
    Superconductivity and flux pinning in Y and heavily Pb codoped Bi-2212 single crystals (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 7669-7671 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Studies of superconductivity and flux pinning were carried out on (Bi1.64Pb0.36)Sr2Ca1−xYxCu2O8+y (x=0, 0.05, 0.11, 0.33) single crystals grown by the self-flux method. X-ray diffraction, transport, and magnetic measurements were performed for purposes of characterization. X-ray analysis revealed that the c lattice parameter systemically decreases as the Y doping level increases. The superconducting transition temperature Tc decreases from 80 to 30 K as x increases. A strong annealing effect on Tc and superconducting volume has been observed. Resistance measurements show that x=0.33 samples are semiconductive over a wide temperature range between 4.2 and 300 K for the as-grown state, but become metallic with Tc of 65–70 K after air or oxygen annealing. Flux pinning was studied by measuring the hysteresis loop at different temperatures and different fields. A peak effect was observed in all the codoped samples. Results show that at low temperatures, the peak field is smaller than in solely Pb doped crystals and decreases as x increases (x〉0.1). However, the peak field at high temperature for the x=0.05 sample is higher than in heavily Pb doped Bi2212 crystals, indicative of a strong pinning due to the codoping. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1356055
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  • 4
    Electronic Resource
    Electronic Resource
    Wavelength dependence of two-beam coupling gain coefficients of BaTiO3:Ce crystals (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 458-460 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two-beam coupling gain coefficients of transmission and reflection gratings in BaTiO3:Ce crystals versus wavelength between 570 and 680 nm have been measured. The former decreases more quickly than predicted by theory. The latter was found to vary significantly with wavelength, while theory shows that it should vary little. In order to explain the experimental results we assumed that the effective carrier number density Neff depends on wavelength. By calculating Neff from the measured results we found that Neff is approximately a linearly decreasing function of wavelength. The slopes and intercepts for the linear functions are given for the two crystals studied. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114535
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  • 5
    Electronic Resource
    Electronic Resource
    Magnetic properties of a novel Pr-Fe-Ti phase : 38th Annual Conference on Magnetism an Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 7120-7121 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In a systematic study of the (Pr1−xTix)Fe5 alloy series, the (Pr0.65Ti0.35)Fe5 alloy has been found to have a dominant phase with either the rhombohedral Th2Zn17 structure or the newly discovered Nd2(Fe,Ti)19 (S. J. Collocott, R. K. Day, J. B. Dunlop, and R. L. Davis, in Proceedings of the Seventh International Symposium on Magnetic Anisotropy and Coercivity in R-T Alloys, Canberra, July 1992, p. 437) structure, depending on the annealing procedure. Powder-x-ray-diffraction patterns and scanning electron microscopy show that the sample annealed at a temperature of 850 °C followed by 1000 °C has the 2:17 structure whereas annealing at 1000 °C directly leads to the new 2:19 structure. Energy-dispersive x-ray analysis yields Pr:Fe:Ti ratios of 10.7:86.2:3.1 for the Pr2(Fe,Ti)17 phase and 9.2:85.9:4.9 for the Pr2(Fe,Ti)19 phase. 57Fe Mössbauer spectroscopy (at 295 K) gives values for the average 57Fe hyperfine field of 15.7 T for the 2:17 phase and 17.5 T for the 2:19 phase, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356698
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  • 6
    Electronic Resource
    Electronic Resource
    Maker fringes in biaxial crystals and the nonlinear optical coefficients of thiosemicarbazide cadmium chloride monohydrate (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1101-1103 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Precise theoretical results of Maker fringes in biaxial crystals are presented which include such necessary corrections as absorption, finite beamwidth effects, and multiple reflections. Their applications to the new nonlinear optical material, organometallic complex crystal thiosemicarbazide cadmium chloride monohydrate (TSCCC, point group Cs-m), and the corresponding experimental values of its six independent nonlinear optical coefficients are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100770
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  • 7
    Electronic Resource
    Electronic Resource
    Light-induced infrared absorption spectra and properties of impurity levels in doped photorefractive BaTiO3 (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 5295-5299 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Light-induced absorption spectroscopy, the decay process of light-induced absorption, and its temperature dependence were investigated to study the properties of the photorefractive impurity levels in doped BaTiO3. Light-induced absorption spectra in one Rh-doped and two Ce-doped BaTiO3 crystals from 0.7 to 3.0 μm were measured and it was found that the light-induced absorption of all these crystals approached zero above ∼1.3 μm. A two-shallow-level model is proposed to explain the biexponential behavior of the decay of the induced absorption in BaTiO3:Ce. The activation energies are deduced to be 0.72 eV for the single-shallow level in BaTiO3:Rh, 0.50 and 0.66 eV for the two shallow levels in the 8 ppm Ce-doped BaTiO3, and 0.50 and 0.74 eV for that in the 30 ppm Ce-doped BaTiO3. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366294
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  • 8
    Electronic Resource
    Electronic Resource
    Structural and magnetic properties of RSr2Fe3O9 (R=La, Y, Pr, and Gd) : The 7th joint MMM-intermag conference on magnetism and magnetic materials (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 7312-7314 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the RSr2Fe3O9 (R=La, Y, Pr, and Gd) materials by several experimental techniques, including x-ray and neutron diffraction, magnetic susceptibility, and Mossbauer spectroscopy measurements. All materials studied are single phase and crystallize in the hexagonal perovskite structure. Magnetic susceptibility studies reveal that, for R=La and Pr, the Fe ions order antiferromagnetically at about TN=190 K. Short range magnetic correlations are observed up to 250 K. For R=La and Pr, 57Fe Mossbauer studies reveal two inequivalent magnetic sextets below 190 K, with the area ratio 2:1. Above TN, one singlet is observed with an isomer shift value typical to Fe4+. For R=Y and Gd, the magnetization curves do not lend themselves to easy determination of the magnetic transition due to an extra magnetic phase which exists up to 350 K. This phase is a result of deficiency of oxygen. The 57Mossbauer spectra at 300 K indicate two superimposed singlet lines, and contain a small magnetic sextet. There is no indication that the R sublattice in RSr2Fe3O9 (R=Pr and Gd) orders magnetically down to 1.5 K. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367834
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  • 9
    Electronic Resource
    Electronic Resource
    Magnetic and superconducting properties of Pr in La1−xPrxBaCaCu3O7 system with 0.0≤x≤1.0 : The 7th joint MMM-intermag conference on magnetism and magnetic materials (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 7315-7317 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the results on structural aspects, magnetic, and superconducting properties of the La1−xPrxBaCaCu3O7 system. Both x-ray and neutron diffraction studies reveal that Pr substitutes isostructurally in the tetragonal LaBaCaCu3O7 (La:1113) system until the complete replacement of La by Pr. The superconducting transition temperature, Tc, determined from ac susceptibility measurements decreases, with increasing x. The relative Tc depression due to Pr in the LaBaCaCu3O7 superconductor is less in comparison to that found for La-site Pr substituted LaBa2Cu3O7 (La:123). While the critical Pr concentration (xcr) to completely suppress the superconductivity in the former is around 70 at. % of Pr at La site, the same is reported as only 30 at. % for the latter. For nonsuperconducting samples, i.e., for x=0.70 and 1.0, possible antiferromagnetic ordering with Neel temperatures, TN, of 4 and 8 K, respectively, are observed from both dc magnetic and heat capacity measurements. Interestingly in the La1−xPrx:1113 system the xcr of Pr is 0.70, and TN of Pr:1113 is 8 K, while for the La1−xPrx:123 system xCr is 0.30 and TN of Pr:123 is 17 K. The results are explained on the basis of distribution of Pr at both RE and Ba sites in the RE:1113 structure. This leads to a lower TN and a less deleterious effect of Pr on superconductivity of La:1113 compared to La:123. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367543
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  • 10
    Electronic Resource
    Electronic Resource
    Superconductivity in a Ag-doped Bi-Pb-Sr-Ca-Cu-O system (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 493-494 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For the Bi-Pb-Sr-Ca-Cu-O (BPSCCO) system, a consistent set of data for Tc, x-ray diffraction, and scanning electron microscopy shows that Ag additions strongly react with BPSCCO to destabilize the 110 K superconducting phase, resulting in a strong depression in Tc and lattice parameters when samples are treated in air or pure oxygen. This is in contrast to the behavior for the Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O systems, which do not show such degradation. However, Ag additions show no effects on Tc and lattice parameters when samples are treated under low oxygen pressure. The formation of a low-melting eutectic liquid with Ag2O-PbO-CuO solid solution affects the composition of the superconducting phase and degrades superconductivity, while the eutectic may be suppressed by reducing the oxygen partial pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103298
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