Stabilization of cubic structure in TlI with Ag+, Br-, NO3-

The solid state phase transitions of Tl(1-x)AgxI, TII(1-x)Br-x and TII(1-x)(NO3)(x) where x = 0.10 are reported. The differential scanning calorimetry (DSC) traces for all three systems show two common endotherms at 172 degrees C and 222 degrees C on first heating but only the 222 degrees C endotherm survived on second heating. The reversible 222 degrees C endotherm suggests a common solid-solid phase transition of the order-disorder type involving a common structure in the host TII, viz, the Pm3m CsCl-type cubic structure, confirmed by its X-ray diffraction pattern. (C) 1997 Elsevier Science Ltd.