Radio and Microwave Spectroscopy of the Betaine Phosphate/Betaine Phosphite Mixed Crystals

The dielectric behaviour of ferroelectric hydrogen bonded deuterated betaine phosphate x /betaine phosphite 1 m x (DBP x DBPI 1 m x ) crystals with x = 0.01, 0.03 is investigated in the region of the ferroelectric phase transition. A small admixture of betaine phosphate is already able to change noticeably the character of the phase transition of deuterated betaine phosphite. In ferroelectric phase the distribution function of the relaxation times of DBP 0.03 DBPI 0.97 broaden continuously with the temperature decrease and deviate from the monodispersive character. The real distribution of the relaxation time of both mixed crystals have been obtained. The temperature behaviour of the local polarization distribution function confirms the inhomogeneous ferroelectric properties of the deuterated betaine phosphite with 3% admixture of betaine phosphate.