Equation of state, Debye-Waller factor, and electrical resistivity of ferroelectrics near their critical point

Structural phase transitions. II. Static critical behaviour

“…eqn. (II.a.18d)):C+/C_ =2.The specific heat has a similar form: also appear in the equation of state as has recently been emphasized byBinder et al (1976). Writing, tbr this equation, the expansion E= Qo[f0(t) +)~(t)(202 + ..…”

“…Measurements of its specific heat (and elastic Fm'ther evidence for the logarithmic corrections is presented by Binder et al (1976), who point out that measurements of the coefficient f2 (eqn. (II.5.20 a)) for TGS are, indeed, consistent with the prediction (II.5.20 c) ( fig.…”

Generalized atomic displacements in crystallographic structure analysis

“…The soft phonons provoke the so-called central peak in the quasielastic response, but their contributions to the DWF remain unimportant. It has been shown (in a treatment restricted to terms quadratic in Q) that the critical part of the DWF near the phase transition of (anti)ferroelectric and similar materials is rigorously determined by the renormalized static phonon frequencies (originating in a shift of sublattices due to static distortions) and exhibits a cusp shape near Tc (Meissner & Binder, 1975;Binder, Meissner & Mais, 1976). A marginal cusp shape of the quadratic DWF was also obtained in a mean-field treatment of a two-dimensional (anti)ferrodistortive transition, while a molecular-dynamics treatment of the same system gave a smooth behaviour of the DWF across the phase transition (Mair, 1986).…”

Lattice mediated interactions and ferroelectric anomalies in the crystal (CH3NH3)5Bi2Cl11(PMACB)

“…It is nevertheless possible that an uniaxial stress along the crystallographic direction [OOl] would be more efficient Downloaded by [University of Western Ontario] at 20:17 17 November 2014 in displacing the system from the tricritical point in analogy with TGSe crystal (Koralewski et al, 1997). It is worth noting that so-called "logarithmic corrections" to the critical behaviour also predict the ratio -4 for the inverse susceptibilities even in the case of an usual critical point (see for example Binder et al, 1976). A measurement under uniaxial pressure can be therefore a test for both hypotheses.…”