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In the present study, thin films prepared as a function of the Bi concentration in the BiPbSrCaCuO system were synthesised. Thin films were fabricated using radio frequency sputtering method. Crystal structure of the films fabricated was determined from X-ray diffraction measurements. The crystal orientation was analysed by X-ray pole figure and in-plane alignment. Both X-ray diffraction and pole figure analysis revealed that crystallinity in the films decreased significantly with decreasing Bi concentration in the system. A systematic decrease in the superconducting transition temperature and hole concentration per CuO plane was obtained with decreasing Bi concentration. The Jc values of the films were calculated using Bean formula. It exhibits a significant dependence on the magnetic field and temperature. It was found that Jc decreased sharply with increasing applied magnetic field. The highest Jc value was found to be 1·06×106 A cm−2 at 10 K, which corresponded to the best flux pinning among the films fabricated.

A theoretical investigation of the binding energy, the radial probability distribution and optical properties (absorption coe±cient (AC) and refractive index change (RIC)) of InGaN/GaN multilayer quantum dot (QD) is presented. The calculations are performed within the e®ective-mass approximation. A shooting method is presented to obtain numerical values for the eigenvalues and eigenfunctions of the structure. The energy eigenvalue, density of probability and optical absorption are compared for cases without and with impurity. It is also found that the ACs and RICs exhibit blue or redshift with di®erent structure of potential pro¯le. The results indicate that the optical properties can be sensitively adjusted by geometry of structure and the presence of impurity.