STRUCTURAL, THERMAL AND TRANSPORT STUDIES ON AG1-XCUXI ESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.25) SOLID-ELECTROLYTE

Preparation and characterization studies on polycrystalline samples of Ag1-xCuxI where x = 0.05, 0.1, 0.15, 0.2 and 0.25, respectively, have been reported. Samples were analysed using powder X-ray diffraction ( XRD) and differential scanning calorimetric (DSC) techniques in order to identify the compositions and phase transition temperatures. A.c. e lectrical conductivity studies were carried out on pelleted specimens of various compositions in the frequency range 65.5 kHz to 1 Hz and ov er the temperature range 293-412 K. DSC results obtained in the temper ature range 373-473 K have shown that the beta- to alpha-phase transit ion temperature is enhanced from 426 K to 438 K when x is increased fr om 0.05 to 0.25. XRD results have indicated that there is a shift in d -spacing when the CuI content is increased, suggesting changes in the crystal structure. Typical XRD patterns recorded for the composition A g0.95Cu0.05I at three different temperatures (room temperature, 373 an d 473 K, respectively) have confirmed that both face-centred cubic and hexagonal phases would be present at room temperature and at 373 K as well, whereas at 473 K the structure would be purely body-centred cub ic in nature. A.c. impedance analysis of the above samples appears to suggest that their electrical conductivity, predominantly due to the m igration of Ag+ ions, lies in the order of 10(-4) S cm-1 at room tempe rature.