Temperature and Pressure Effect on the Anisotropy of Dielectric Permeability in KDP and DKDP Crystals

Abstract

Temperature dependences of longitudinal and transverse dielectric permeability of KDP and DKDP crystals are studied at different values of hydrostatic pressure in order to determine the pressure behaviour of the isotropic point for these crystals. The isotropic point temperature in KDP crystals at atmospheric pressure is T i = 186 K at the measuring field frequency 1 kHz and T i = 176 K at the frequency of 1 MHz. In DKDP crystals the isotropic point is achieved at the temperature T i = 300 K ( 1 kHz) and T i = 253 K ( 1 MHz). The hydrostatic pressure increase results in the reduction of the isotropic point temperature with the pressure coefficients ∂T i /∂p = −4.3 K/kbar for KDP and ∂T i /∂p = −2.9 K/kbar for DKDP. The analysis of the experimental results in the framework of the Blinc-Žekš pseudospin formalism has shown a good agreement between the calculated and the experimentally obtained temperature of the isotropic point for KDP crystals.

External field effect on the anisotropy of dielectric permeability of KH_{2}PO_{4} and NaKC_{4}H_{4}O_{6}· 4H_{2}O crystals under high pressure

“…Three characteristic features can be seen in this dependence: a step of dielectric permeability at the phase transition temperature T C = 122 K, a maximum in the ε a (T ) dependence at the temperature T max = 130 K, and an inflection point at T f = 172 K. The existence of a maximum of dielectric permeability at T > T C was registered in KMnF 3 and NH 4 H 2 AsO 4 antiferroelectric crystals [8]. In our earlier papers [9][10][11] the first experimental studies of the effect of external hydrostatic pressure on the temperature dependence of transverse dielectric permeability ε a for KDP crystal were described. The hydrostatic pressure increase to 6.5 kbar results in a shift of the ε a (T ) curves towards lower temperatures, the T C , T max , and T f values varying linearly with pressure with the following coefficients: dT C /dp = −4.8 · 10 −2 K/MPa; dT max /dp = −5.4 · 10 −2 K/MPa; dT f /dp = −5.4 · 10 −2 K/MPa.…”

Electro-Optic Characteristics of a Cooled Deuterated Potassium Dihydrogen Phosphate Crystal

“…4. 31) For a parallel plate capacitor, the electric energy required at the half-wave voltage can be numerically calculated using…”

Influence of the Piezoelectric Ringing on the Temperature of the Beta Barium Borate Crystal

“…The investigations of the temperature impact on the polarization of the light of the Pockels cells based on the DKDP crystals have already been performed [9][10][11]. The results presented in [9][10][11] show that the temperature change influences the polarization and, as a consequence, the CR.…”