Abstract
Temperature dependences of dielectric permittivity ϵ33, piezoelectric constant d36 and elastic compliance S66 of K1-x(NH4)xH2PO4 ferro – antiferroelectric (FE - AFE) mixed crystals have been studied within temperature range 30 – 300 К. It was found a considerable contribution of the strain component x6 to polarization P3 near the FE transition temperature due to piezoelectric effect. Piezoelectric contribution to dielectric response in the vicinity AFE phase transition is weaker. It leads, in particular, to difference in the both shapes and positions of ϵ33 and S66 anomalies for K0,25(NH4)0,75H2PO4 single crystal near the transition temperature.
Acknowledgments
Authors thank professor S.A. Gridnev for the fruitful discussion and doctor R.M. Fedosyuk for the crystals grown. Authors express great appreciations to professor V.S. Zakhvalinskii as well as to doctors E. Pilyuk and A. Khmara for their technical assistance in various parts of this work.
This work was supported by Russian Foundation for Basic Research (Grants N 11-02-90435-a and N 13-02-90473-a) and by State Foundation for Fundamental Studies of Ukraine (Grant N Φ53.2/070).