An Experimental Investigation of Phase Transition in a Superionic Mixed Composite System of [Cu2HgI4:0.2 AgI] Doped with KBr

A novel composite superionic system, [Cu2HgI4:0.2 AgI]:0.xKBr, (x=0.2, 0.4, 0.6 mol. wt. %), was prepared and [Cu2HgI4:0.2 AgI] composite system used as the host. Electrical conductivity was measured to study the transition behavior at frequencies 100 Hz, 120 Hz, 1 kHz, and 10 kHz in the temperature range 90–170 °C using a GENRAD 1659 RLC Digibridge. Conductivity increased sharply during the β - α phase transition. Upon increasing the dopant-to-host ratio, the conductivity of the superionic system exhibited Arrhenius (thermally activated)-type behavior. X-ray powder diffraction, DSC and DTA were performed to confirm the doping effect and transition in the host. The phase transition temperature decreased with an increase in the dopant concentration. Activation energies in eV for pre- and post-transition phase behavior are also reported. Due to an interaction between [Cu2HgI4:0.2 AgI] and KBr, the addition of the dopant KBr shifted the phase transition of the host, [Cu2HgI4:0.2 AgI].