Effect of hydrostatic pressure on the diffuse phase transition in lead iron niobate

For ceramic Pb(Fe 1 2 Nb 1 2 )O 3 , the permittivity ϵ has a broad maximum at the ferroelectric transition temperature Tt. The value of the exponent for the logarithmic plots of the reciprocal ϵ versus reduced temperature above Tt is 2.0 and is almost independent of pressure p. With increasing p, Tt decreases with dTt/dp=-3.7 K/kbar and the maximum value of ϵ decreases.