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Effect Of Hydrostatic Pressure On The Incommensurate Phase Of K2Seo4, W. Press, C. F. Majkrzak, J. D. Axe, John R. Hardy, N. E. Massa, F. G. Ullman
Effect Of Hydrostatic Pressure On The Incommensurate Phase Of K2Seo4, W. Press, C. F. Majkrzak, J. D. Axe, John R. Hardy, N. E. Massa, F. G. Ullman
John R. Hardy Papers
A neutron scattering study of the effect of hydrostatic pressure on the incommensurate phase transformation in K2SeO4 was performed in order to obtain information concerning the nature of the competing forces that give rise to a structural instability at a general wave vector. It was found that an increase in pressure lowers the transition temperature (dTi/dPi = - 6.5 K/kbar) and results in a smaller value of the initial incommensurate wave vector. The pressure dependence of the incommensurate to ferroelectric phase transition was also investigated (dTc/dPc = …
Theoretical Lattice-Dynamical Studies Of The Incommensurate Phase Transformation In K2Seo4, M. S. Haque, John R. Hardy
Theoretical Lattice-Dynamical Studies Of The Incommensurate Phase Transformation In K2Seo4, M. S. Haque, John R. Hardy
John R. Hardy Papers
We have made detailed lattice-dynamical studies of the origin of the incommensurate phase transition in potassium selenate. These were based on a rigid-ion model with Coulomb interactions, and also short-range interactions between restricted numbers of close neighbors. The associated short-range force constants were determined using the static equilibrium conditions for the crystal and the observed Raman frequencies. The calculations were made for the room temperature structure using the quasiharmonic approximation in which the effects of varying temperature were simulated by varying the short-range force constants. In this way we were able to show that the crystal has a low-frequency optic …