Vanishing of the phase transitions and quantum effects in K2SeO4at high pressure

The effects of pressure on the dielectric properties and phase transition in K2SeO4 were investigated. The incommensurate-to-commensurate ferroelectric transition vanishes at 0.73 GPa, and the paraelectric-to-incommensurate transition is expected to vanish at ∼ 1.13 GPa. These large pressure effects can be understood in terms of the delicate balance between Coulomb and short-range interactions. The results show the increased influence of quantum effects on approaching the displacive limit (i.e. Tc = O K), and they confirm the existence of a γ = 2 regime in the temperature dependence of the susceptibility, as predicted by recent theories.