• C S Sunandana

      Articles written in Pramana – Journal of Physics

    • A PSD-based electronic system for AC response studies of superionic conductors

      P Balaya C S Sunandana

      More Details Abstract Fulltext PDF

      An electronic system based on quadrature oscillator, current-to-voltage converter and phase sensitive detector (PSD) has been designed and constructed for measurement of AC electrical conductivity and complex impedance/admittance on ionic and superionic conductors at several frequencies upto 60 kHz. The design incorporates a CMOS FET switch controlled by two anti-square reference signals for rectification and a differential amplifier for summation and impedance matching. The performance of the system has been demonstrated and the measurement possibilities discussed.

    • Electronic conductivity of mechanochemically synthesized nanocrystalline Ag1−xCuxI system using DC polarization technique

      D Bharathi Mohan C S Sunandana

      More Details Abstract Fulltext PDF

      A study of electronic conductivity using the DC polarization technique has been carried out for AgI and Ag1−xCuxI (where x=0.05, 0.15, 0.25) solid solutions over a range of temperatures from 300 K to 473 K. A diode-like current-voltage characteristics arises from microscopic p-n junctions an enhanced electronic conductivity of the order of 10−3A is observed for undoped AgI and Cu-doped AgI. Activation energies (Ea) for electronic conductivity obtained from log σ−1 cm−1) vs. 1000/T (K−1) were 0.48, 0.6, 0.74 and 1.01 eV for AgI, Ag0.95Cu0.05I, Ag0.85Cu0.15I and Ag0.75Cu0.25I solid solutions respectively. The near-twofold increase in activation energy (1.01 eV) observed upon 25% Cu doping is due to the substantial concentration of current carriers/holes injected by Cu while replacing Ag+ in AgI.

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