Influence of oxygen content on the cathodoluminescence of YBa2Cu3O7−x (original) (raw)
Related papers
Cathodoluminescence and microRaman analysis of oxygen loss in electron irradiated YBa2Cu3O7−x
Journal of Applied Physics, 1993
The effect of oxygen loss on the luminescence of YBazCu307-, has been investigated by cathodoluminescence (CL) in the scanning electron microscope (SEM) and by Raman microprobe measurements. The results herein indicate that a CL band at 530 nm is related to oxygen loss rather than to impurity phases such as YZ03 formed in the material by electron irradiation in the SEM.
Study of the oxygen distribution in YBa2Cu3O7−x ceramics by (n, α) radiography technique
Journal of Radioanalytical and Nuclear Chemistry Articles, 1993
A technique to determine the oxygen distribution in high T c superconducting YBa2Cu3OT_ X ceramics has been developed which is based on th~ (n, o 0 radiography method. The technique enables the non-destructive study of superconducting ceramics as well as monocrystal samples with spatial resolution not worse than 1 ~tm at a relative standard deviation of 1.5%. This technique is used to study the influence of radiation-stimulated diffusion of oxygen on the formation of the superconducting phase in an yttrium ceramic. The oxygen distribution in the samples with a narrow transition (AT-1 K) and with a lrausition widened (AT-10 K) by thermal and thermo-radiative treatment is compared in the experiment. The oxygen distribution radiographs of irradiated and unirradiated samples provide strong evidence for the influence of irradiation oa the ordering of superconducting ceramics structure.
Effects of oxygen deficiency on the optical spectra of YBa2Cu3O7−x
Solid State Communications, 1988
We report on the variation of ellipsometric spectra of the YBa2Cu30r_x high Z', compounds with oxygen content 0 < z 5 1. Beside the structures observed in the z = 0 compound two new, rather intense peaks are observed at N 1.75 eV and N 4.1 eV in the semiconducting compound (z > 0.5). Their intensity strongly depends on the oxygen content, whereas the energy shows a weak dependence both on oxygen content and temperature. Several minor features become significant upon cooling the samples to 7 K. We associate the 4.1 eV peak to excitations involving transitions from Ba(5d) and/or Cu(3d) states to O(2p) states. The 1.75 eV peak is possibly due to Cu(3d) and O(2p) states.
In situstudies of microstructural changes in YBa2Cu3O7−xduring O and He irradiation
Philosophical Magazine A, 1989
We have studied the microstructural changes occurring in YBa,Cu,O,-, (the so-called '123' phase) upon room temperature irradiation by He+ and O', in situ, on samples that had been thinned by ion milling before irradiation, using a transmission electron microscope on line with the ion implanter. In previous work on samples crushed from the bulk or on films ion-milled after irradiation, the samples amorphized above a threshold of about 0 3 displacement per atom. In the present case, no amorphization is observed, instead, precipitation of Cu,O occurs, indicating complete demixing of the ceramic. This process seems to nucleate at the ion-milled surfaces. For a displacement-per-atom ratio of about 010, a change from the orthorhombic to the tetragonal structure of the '123' compound occurs. It is suggested that the result is quite general. The effects of the microstructural changes on the electrical properties are briefly discussed.
Nuclear Tracks and Radiation Measurements, 1993
A technique to determine the oxygen distribution in high Tc superconducting YBa2CU3OT_ x ceramics has been developed based on the (n, ,,)-radiography method. The technique allows for the study of spatial oxygen distribution in superconducting ceramics as well as monocrystal samples without destruction of the sample, with spatial resolution not less than 1/~m and a relative standard deviation of 1.5%. By means of the technique elaborated on, the influence of the radiation-stimulated diffusion of oxygen on the super-conducting phase formation in yttrium ceramics was studied. In the experiment the oxygen distribution in the samples with a narrow transition (AT ~ 1 K) and a widened one (AT ~ 10 K) were compared. The oxygen distribution radiograms for samples annealed under y-irradiation provide strong evidence for the influence of the irradiation on crystalline ordering in the basis plane.
Spectroscopy of the Irradiated YBa2Cu3OxSuperconductors
Acta Physica Polonica A, 1993
Complex investigations of the photoinduced changes in YBa2Cu3O x single crystals were performed. As laser sources the low-power He-Ne, He-Cd, He-Se, N2 lasers and YAG:Nd, XeCI pulsed lasers were used. For the investigations the crystalline samples both in super-and semiconducting phases were chosen. A considerably strong dependence of a defectiveness parameter x on the laser power, wavelength and external conditions was observed. The oxygen parameter x shows a tendency to increase for the initially semiconduoting phase and to decrease for superconductors. The most interesting result were obtained using XeCI excimer laser, where corresponding changes ν ere observed only under applied hydrostatic pressure (up to 200 MPa) in oxygen atmosphere. In all the cases the penetration depth of the new induced superconducting phase was within 5.5-6.5 μm.
Luminescence and EPR studies of YBO3:U
Journal of Physics and Chemistry of Solids, 2009
Yttrium borate doped with uranium was prepared by mixing and heating yttrium oxide obtained through oxalate precipitation route, boric acid and requisite amount of nuclear-grade uranium oxide at high temperature. Photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) studies were carried out on gamma-irradiated doped/undoped yttrium borate samples in the temperature range 300-600 K. TSL studies showed the presence of two glow peaks at 414 and 471 K. PL studies along with lifetime decay investigation suggested uranium goes in the matrix as UO 2 2+. EPR studies showed the presence of O 2 À radical ion along with electron trapped in defect centres, which might have been produced for charge compensation. Apart from this, CO 2 À radical was also observed in the system having its origin from residual oxalate ion. Temperature dependence EPR studies of the observed radical confirmed the involvement of the CO 2 À and dioxide radical ion in the observed glow peaks. By correlating the TSL, PL and ESR data, probable mechanism is proposed for the observed TSL glow in the system.