Journal ArticleDOI
Theory of the Transition in KH2PO4
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In this paper, the theory of spontaneous polarization along the axis of the crystal, resulting in a well-known transition, similar to Rochelle salt, with polarization below the Curie point was worked out.Abstract:
Potassium dihydrogen phosphate contains phosphate groups connected by hydrogen bonds. Different possible arrangements of the hydrogens result effectively in different orientations of the (H2PO4)— dipoles. Since these have the lowest energy when pointing along the axis of the crystal, there is a tendency toward spontaneous polarization along this axis, resulting in the well‐known transition, similar to Rochelle salt, with polarization below the Curie point. The theory of this transition is worked out, using statistical methods to count the number of arrangements of hydrogens consistent with each total polarization of the crystal, and deriving the free energy. It is found that the theory predicts a phase change of the first order, with sudden transition from the polarized state at low temperature to the unpolarized state at high temperature, rather than the lambda‐point transition or phase change of the second order which is observed. However, the observed transition is confined to a very narrow temperature range compared to that predicted, for instance, by the Weiss theory, so that it seems as if it might be merely a broadened transition of the first order. It is suggested that the broadening may result from the irregular shifts of transition temperatures of individual domains in the crystal on account of stresses resulting from the large piezoelectric effect and the resulting deformation of the crystal below the transition point. The susceptibility above the Curie point comes out by the theory to be 4.33 times as great as it should according to the Weiss theory, a result which seems to be in general agreement with experiment. The entropy change in the transition is given by the theory as 0.69 unit, somewhat smaller than the observed value of about 0.8 unit. No explanation is suggested for this discrepancy.read more
Citations
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The Proton-Configurational Entropy of NaH3(SeO3)2
TL;DR: In this article, the validity of previous entropy calculations on STHS is reexamined from the view of crystal symmetry, and it is shown that the results of previous calculations based upon an implicitly loosened condition are applicable to STHS if a suitable transference of bond assignment is admitted.
Journal ArticleDOI
On the proton dynamics at the AsO4 4- radical in the paraelectric phase of arsenates of the KDP family
J. Gaillard,P. Gloux,B. Lamotte +2 more
Journal ArticleDOI
Effect of the magnetic field on the ferroelectric transition of KD2pO4 measured by a high resolution and super-sensitive differential scanning calorimeter
TL;DR: In this paper, the magnetic effect on the ferroelectric transition of single crystalline KD 2 PO 4 (DKDP) was measured by using a high resolution and super-sensitive differential scanning calorimeter (DSC) working in a magnetic bore.
Journal ArticleDOI
Integrability of the odd eight-vertex model with symmetric weights
TL;DR: In this paper, the integrability properties of the odd eight-vertex model on the square lattice have been investigated, and it has been shown that these models give rise to a generic sheaf of -matrices satisfying the Yang-Baxter equations.
Journal ArticleDOI
Statistical perturbation theory of order-disorder ferroelectrics: First perturbative correction
TL;DR: In this article, an equation-of-motion method is used to calculate excitation energies of proton tunneling modes in KD2PO4 using an Ising pseudo-spin representation of the proton Hamiltonian.
References
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The Structure and Entropy of Ice and of Other Crystals with Some Randomness of Atomic Arrangement
Journal ArticleDOI
Eine neue seignette-elektrische Substanz
G. Busch,P. Scherrer +1 more
TL;DR: Wasps social and solitary, problems of ins t inct and intelligence, development and behavior, and notes on how to deal with these problems and more.
Journal ArticleDOI
Properties of Rochelle Salt
TL;DR: In a qualitative way, the anomalous properties of Rochelle salt can be explained on the basis of four different theories: ($a$) on the dipole theory, ($b$) by assuming polymorphic transitions at the Curie points, ($c) by postulating an anomalous piezoelectric effect, and ($d$) with an interaction theory which assumes that the structure and the fundamental properties of the crystal have no unusual characteristics as mentioned in this paper.