Journal of Physical Studies 3(4), 502–512 (1999) DOI: https://doi.org/10.30970/jps.03.502 UNIAXIAL PRESSURE INFLUENCE ON KH2PO4-TYPE FERROELECTRICS

I. V. Stasyuk¹, R. R. Levitskii¹, A. P. Moina¹, I. R. Zachek², A. S. Duda¹, M. O. Romanyuk³, V. J. Stadnyk³, Ye. V. Shcherbina^4
1Institute for Condensed Matter Physics
1 Svientsitskii Str., Lviv, UA-79011, Ukraine
²State University "Lvivs'ka Politekhnika"
12 Bandera Str., Lviv, UA-79646, Ukraine
³Ivan Franko National University of Lviv
50 Drahomanov Str., Lviv, UA-79005, Ukraine
⁴Institute for Single Crystals
60 Lenin Pr., Kharkiv, UA-61141, Ukraine

We performed experimental investigations of deuteration and uniaxial $p=-σ_i'$ pressure influence on temperature dependence of the birefringences and transition temperature of K(H$_{1-x}$D$_{x})_2$PO$_4$ crystals. On the basis of the previously proposed model for a strained KD$_2$PO$_4$ crystal, we study the effects of uniaxial $p=-σ_3$ pressure on the phase transition and static dielectric properties of highly deuterated K(H$_{1-x}$D$_{x})_2$PO$_4$ crystals. The obtained theoretical results are compared with the available experimental data and earlier theoretical calculations, concerning the hydrostatic pressure effects. The role of D–site distance in the phase transition and dielectric response of the crystals is discussed.

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