Journal of Physical Studies 6(2), 197–204 (2002) DOI: https://doi.org/10.30970/jps.06.197 HYDROSTATIC PRESSURE INFLUENCE ON DIELECTRIC PERMITTIVITY OF KH2PO4 AND KD2PO4 IN THE PIEZOELECTRIC RESONANCE REGION R. R. Levitskii1, A. G. Slivka2, A. P. Moina1, P. M. Lukach2, A. M. Guivan2 1Institute for Condensed Matter Physics, National Academy of Sciences of Ukraine 1 Svientsitskii Str., Lviv, UA–79011, Ukraine 2Uzhgorod National University, Physics Department, 32 Voloshyn Str., Uzhgorod, UA–88000 Ukraine

We measured transverse and longitudinal dielectric permittivities of \kdp\ and \dekdp\ in the piezoelectric resonance frequency region under the hydrostatic pressure. The transverse permittivity of both crystals decreases with pressure in the paraelectric phase and increases in the ferroelectric phase. The pressure dependence of the transverse permittivity of deuterated \dekdp\ is well described by the presented theory. The longitudinal dynamic permittivity of the crystals obeys the Curie-Weiss law above the transition point, the pressure dependence of the Curie constant accords with the earlier data for a static permittivity. Near the transition point, multiple peaks in the longitudinal permittivity are revealed.

PACS number(s): 77.80.Bh, 77.84.Fa

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