Both real and imaginary parts of the dielectric constants are measured in the pellet samples of Betaine Phosphate-Arsenate ($BP_xA_{1-x}$ or $BPA_{-x}$) over the whole range of mixing concentration x in the temperature range from room temperature to 24K. We could observe the dipole glass behavior, coexistent with the ferroelectric phase for the sample x = 0.5, 0.6 and with the antiferroelectric phase for sample of x = 0.7 at low temperatures, while ferroelectric and antiferroelectric phase transitions were observed for x ≤ 0.4 and x ≥ 0.8 respectively.
Dielectric properties are also studied in crystal samples of x = 1.0, 0.7, 0.6. In Betaine Phosphate (x = 1.0), temperature dependence of real part of dielectric constant is analyzed in terms of the Pseudo One Dimensional Ising Model. In mixed crystals (x = 0.7, 0.6), we could not observe the dipole glass behavior yet, but a finite hysteresis between cooling and heating runs. On cooling run we have observed an additional cusp, possibly indicating a metastable intermediate phase.
