Comparative Investigation of the Specific Heat of KH₂PO₄ (KDP) and KD₂PO₄ (DKDP) Single Crystals

Abstract

Abstract The surplus entropy of the phase transition is measured for KH 2 PO 4 and KD 2 PO 4 crystals. The corresponding values are as follows: (0.69 ± 0.02) and (0.96 ± 0.08) for KDP and DKDP, respectively. The temperature dependence of the specific heat of DKDP shows that the phase transition in the crystal is of the first order. For the KDP crystals, the analytic form of the surplus specific heat is approximately Δ c σ, E ∼ ( T c – T ) −δ , δ = 0.51 ± 0.01. Theoretical estimates and experimental measurements are made of the effect of an electric field on the specific heat.