Pressure effect on the phase transitions of the superionic conductors KAg4I5and NH4Ag4I5

Abstract
The pressure dependence of the first order and the second order transition temperature (Tc1 and Tc2) for MAg4I5 (M=K and NH4) is measured in the range of pressure up to 7 kbar. The variations of Tc1 and Tc2 with pressure (p) show a large quadratic pressure dependence: (p-p0i)2=Ai(Tci-Tc0i), where p0i, Ai and Tc0i (i=1, 2) are the pressure independent constants. The correlation of the pressure dependence of Tc1 and Tc2 for MAg4I5 (M=K, NH4 and Rb) is clarified.