A STUDY OF OPTICAL PROPERTIES OF PHOSPHATE AND TELLURITE SEMICONDUCTING OXIDE GLASSES

Glass samples in the system of (p_2o_5)75-(cuo)_25-x-(cdo)x/(p_2o_5)_75-(cuo)_25-x- (zno)x/(p_2o_5)_75-(cuo)_25-x-(v_2o_5)x/(p_2o_5)_50-(teo_2)_50-x-(cdo)x/(p_2o_5)_50-(teo_2)_50-x-(zno)x and (p_2o_5)_50-(teo_2)_50-x-(v_2o_5)x glasses of different compositions where (x = 0, 5, 10, 15,20) were prepared by the melt-quenching technique. optical absorption spectra of different compositions were recorded in the visible and uv regions and optical parameters such as optical energy gap (eopt) and band tails (eo) were determined by urbach formula, the measurements for phosphate glasses of optical energy gap (eopt) (p_2o_5)_75-(cuo)_25-x-(cdo)x have been determined and founded between (3.75-4.185) ev, (p_2o_5)_75-(cuo)_25-x-(zno)x the value of optical energy gap is between (3.75-4.25)ev, (p_2o_5)_75-(cuo)_25-x-(v_2o_5)x the (eopt) is between (3.75-4.2)ev. for tellurite glasses the measurements of optical energy gap (eopt) of (p2o5)50-(teo_2)_50-x-(cdo)x have been determined and founded between (3.825-4.25)ev, (p_2o_5)_50-(teo_2)_50-x-(zno)x the (eopt) is between (4.035-4.2)ev, (p_2o_5)_50-(teo_2)_50-x-(v_2o_5)x the value of optical energy gap is between (3.875-4.335)ev, it was found that the fundamental absorption of these glasses is dependent upon compositions and arises from forbidden indirect transitions. the most satisfactory results were obtained with the theory davis and mott for forbidden indirect transitions.