Phase transition in potassium dihydrogen phosphate induced by an applied static electric field

1996 ◽  
Vol 54 (9) ◽  
pp. 6027-6030 ◽  
Author(s):  
S. G. C. Moreira ◽  
F. E. A. Melo ◽  
J. Mendes Filho
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Static Electric Field ◽  
Potassium Dihydrogen

Effect of optical activity on electro-optic measurements in crystals of the potassium dihydrogen phosphate family

2012 ◽  
Vol 45 (5) ◽  
pp. 950-962 ◽  
Author(s):  
Marek Izdebski
Keyword(s):  
Electric Field ◽  
Optical Activity ◽  
Point Group ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Linear Quadratic ◽  
Potassium Dihydrogen ◽  
Electro Optic ◽  
Effective Coefficients ◽  
New Interpretation

Crystals of the potassium dihydrogen phosphate family in their paraelectric phase belong to point group \overline 4 2m, which allows for natural optical activity and electric field-induced optical activity related to the linear and nonlinear electrogyration effects. This work presents a theoretical analysis of the influence of these effects on measurements of the linear, quadratic and fourth-order electro-optic coefficients. Both the polarimetric technique and a method based on Michelson interferometry are considered. A number of configurations of the light path and the electric field directions were analyzed, and it was found that the influence, when it appears, is usually negligibly small. Thus, no previously reported experimental data need a new interpretation. However, in future measurements of some effective coefficients of the quadratic electro-optic effect using the dynamic polarimetric technique, the contribution of the quadratic electrogyration may no longer be negligible after improving the resolution from 10−21to 10−22 m2 V−2. This work also shows that the quadratic electrogyration described by the β31coefficient may be decoupled from the linear and quadratic electro-optic effects in measurements performed by the polarimetric method.

On the ferroelectric behaviour of potassium dihydrogen phosphate

1959 ◽  
Vol 250 (1261) ◽  
pp. 266-285 ◽  
Keyword(s):  
Phase Transition ◽  
Ferroelectric Properties ◽  
Potassium Dihydrogen Phosphate ◽  
Energy Parameter ◽  
Dihydrogen Phosphate ◽  
Hydrogen Ions ◽  
Ionic Model ◽  
Potassium Dihydrogen ◽  
Configurational Energy ◽  
The Difference

In this paper we consider the properties of potassium dihydrogen phosphate (K D P). In the introduction we compare the behaviour of K D P with that of some isomorphous crystals. From this comparison we conclude that the hydrogen bonds play a deciding part in the phase transition, although the magnitude of the polarization seems to be determined by the heavy ions. As a first theoretical approach we apply the first Bethe approximation to an Ising model, based on the hydrogen lattice of K D P. This model contains an additional configurational energy U as compared to Slater’s work. His results are obtained in the limit as U → ∞. We find a phase transition for all positive values of U , but according to whether U is larger than or smaller than a certain value, which is about 3/2 times Slater’s energy parameter, the transition is a first-or a second-order one. After that we consider an ionic model of K D P which we treat as a polar hydrogen lattice with interpenetrating ionic potassium, phosphorus, and oxygen lattices. As far as possible the detailed behaviour of the constituent atoms is taken into account. The rigidity of the hydrogen bond, the effect of the configurational energy of the hydrogen ions about the phosphate tetrahedra, and the displacements of the K, P and O ions from their lattic sites all appear explicitly in the calculations. It is not found possible to choose our parameters in such a way that we can fit the complete temperature dependence of the susceptibility. The combination of a hydrogen triggering mechanism and the neutron diffraction data imply effective changes of opposite sign for the K and P ions, in disagreement with the expected properties of electro-positive atoms. On the other hand, however, our model gives not only a qualitative account of the similarity of the ferroelectric properties of K D P and its isomorphs, but also of the difference in the temperature independent part of the susceptibility in the ferroelectric and paraelectric phases of K D P, respectively.

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