Centre for Cognitive Sciences

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Browsing Centre for Cognitive Sciences by Author "Bhatnagar, A. K."
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    Optical energy gap of amorphous selenium: Effect of annealing
    ( 1985-12-01) Bhatnagar, A. K. ; Reddy, K. V. ; Srivastava, V.
    The optical energy gap of amorphous Se powder has been determined by a photo-acoustic method and has been found to be 1.99+or-0.02 eV. On annealing, the gap decreases linearly as a function of annealing temperature towards that of the crystalline selenium.
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    Te substitution in disordered dilute Se1-xTex alloys
    ( 1998-12-01) Bhatnagar, A. K. ; Srivastava, Vipin ; Reddy, K. V.
    Photoacoustic absorption measurements at room temperature are reported for Se1-xTex alloys in both crystalline and amorphous states for 0
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    The influence of antimony impurity on optical and electrical properties of amorphous selenium
    ( 1992-12-01) Venugopal Reddy, K. ; Bhatnagar, A. K. ; Srivastava, V.
    Amorphous Se1-xSbx alloys were prepared using a conventional rapid quenching technique. It is found that antimony can only be substituted up to approximately 10 at.% in selenium to produce Se-Sb glassy alloys. The photoacoustic technique is employed for the first time to determine the optical energy gaps of Se1-xSbx glasses. The optical energy gap of amorphous selenium is found to be 1.99+or-0.02 eV. It reduces drastically on substitution of 2 at.% Sb after which its variation with x is small. The activation energies of Se1-xSbx glasses have been determined from the temperature dependence of their electrical resistivities. The activation energy as a function of x also shows a sudden decrease in the range 0.01