Diffusion of Cu in ZnS thin films was investigated in the temperature range 80–400 °C using the energy‐dispersive X‐ray fluorescence (EDXRF) technique. ZnS thin films were deposited by spray pyrolysis on a glass substrate. The temperature dependence of the Cu diffusion coefficient is described by the equation D = 1.4 × 10−10 exp [–(0.18 eV)/kT]. It is shown that diffusion doping of n‐type ZnS by Cu is accompanied by a significant increase in resistivity and a slight decrease in the band gap of the ZnS films. The observed results are attributed to the migration of Cu in polycrystalline ZnS films by means of diffusion both along grain boundaries and into grains. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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The vertical force density curves of (Sm123)1−x(Yb211)x high temperature superconductor (HTS) samples prepared by a melt‐powder‐melt‐growth technique were measured during vertical and lateral traverses in zero field cooling (ZFC) regime for various doping levels (x). It was determined that the maximum vertical force density of the samples increases when the doping level increases and after certain level of the doping the force saturates. The pinning properties, which create attractive force, were enhanced up to a certain Yb211 doping level by introducing locally suppressed superconducting regions. These results indicate that the optimization fabrication conditions and Yb211 doping level should be further investigated for larger dimensional samples to enhance technological applicability. The frozen image model was used to predict the experimentally measured levitation force between a permanent magnet (PM) and the superconductor samples. Various configurations of the PM/HTS force interaction were tested according to the magnet and superconductor size. The doped HTS samples do not show very strong diamagnetic behavior as the frozen image model predicts. The levitation force behavior regarding the dimensions of the PM and HTS indicates an illustration how the diamagnetic behavior of the superconductor transforms into the flux pinning.

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