The Effect of the Hydrostatic Pressure on the Antiferroelectric Transition of Pb(Mg 1/2 W 1/2 )O 3

The dielectric properties of Pb(Mg 1/2 W 1/2 )O 3 were measured at various pressures up to 8 kbar. With increasing pressure p , the antiferroelectric transition temperature T n decreases with d T n /d p =-3.8±0.2°C/kbar, the extrapolated Curie-Weiss temperature T 0 increases with d T 0 /d p =1.4±0.2°C/kbar, and the maximum value of the permittivity ε , ε max , is almost constant below 4 kbar and then increases. This increase in ε max with p is associated with the decrease in the difference Δ T (= T n - T 0 ) with p . The Δ T extrapolates to zero at p t ≈18 kbar where the change from the antiferroelectric transition to the ferroelectric one is expected. The dielectric properties are interpreted in terms of a phenomenological theory.