Melt quenching of a 1:4 mixture of NH4I and AgI was attempted in order to achieve rapid, large-scale synthesis of ("145"). The characterization of the as-quenched and annealed samples through DSC, IR and X-ray diffraction reveal (i) the thermodynamic evidence for "145" through endotherms at 235-degrees-C (incongruent melting) and -75-degrees-C (phase transition); (ii) disordered NH4+ groups and (iii) the need to anneal at temperatures below 147-degrees-C to obtain pure "145" phase. Crystallization from KI solution offers another attractive method for synthesis of stable "145".