Dielectric relaxation in ferroelectric (CH₃)₂NH₂H₂PO₄and its isotope effect

Abstract

Abstract The temperature dependences of the real and imaginary parts of the complex dielectric constant of (CH3)2NH2H2PO4 and its partially deuterated crystal, (CH3)2N(H1-x D x )2(H1-x D x )2PO4, were measured in a frequency range between 1 MHz and 1 GHz. The results obtained in the present study indicate that the crystal of (CH3)2N(H1-x D x )2(H1-x D x )2PO4 exhibits remarkable dielectric relaxation in the microwave frequency range, and exhibits critical slowing-down near Tc . It is therefore concluded that the ferroelectric phase transition is of order-disorder type, and the transition temperature and the relaxation time are enhanced by the increase of the deuterium concentration.