الفهرس 
Aim of the workOnly 14 pages are availabe for public view
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Abstract
Samples of the system [YBa2Cu307..oh-x(Te02)x with x = 0.0, 0.2, 0.7, 1.2, 1.7 and 2.2% by weight were prepaired by solid-state reaction technique . XRD pattern for the obtained samples showed that they were composed of two new phases, Ba2CuTe06 & Y2BaCu05 mixed with the parent phase Yl23. The latter showed a transformation tendency to tetragonal phase with increasing Te-content. This led us to conclude that the Ba2CuTe06 phase does not simply co-exist with that of YBa2Cu307 but it somehow alters the ammmt of oxygen defects in its· lattice structure. D.C. resistivity
measurement showed that increasing Te-content decreased Tc values for he samples and increased its semiconducting behavior in normal state.
The six samples were irradiated with 6°Co gamma source
four successive times with 0.25 M Gy dose in each time. XRD pattern for the irradiated samples showed a slight change in the characteristic diffraction peaks of both the Y123 and also the
_two new phases. The transformation tendency of Y123 to
tetragonal phase was slightly increased. This was attributed to the collisions between oxygen atoms along Cu-0 chains and the energetic Compton electrons produced during irradiation. The repeated exposure to gamma radiation decreased the degree of orthorh9mbicity.It was also found that Tc-values decreased after each dose and this was attributed to the partial destruction of weak links by gamma quanta and the inhomogeniety increase in the Y123 grains caused by Compton electrons.