Search

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.

Raman spectra of the internal modes of K2SeO4 in the 300-450 cm-1 and 800-950 cm-1 ranges, contain the same nine lines for each of the four crystallographically-allowed irreducible representations of the Raman tensor and except for thermal broadening, remain essentially the same from 20 degK to above 400 degK. From symmetry, 6A1g, 6B1g, 3B2g and 3B3g lines are expected in the 135K