FERROELECTRICITY IN 3C6H4(OH)2.CH3OH

The pyroelectric charge of 3C6H4(OH)2·CH3OH was measured after poling the crystal. It was found that the crystal becomes ferroelectric below the phase transition point, Tc=63.7 K, and has spontaneous polarization along the c axis with a value of 6.15 × 10-3μC/cm2 at 20 K. The dielectric constant was measured at a frequency of 330 Hz along the a and c axes. The dielectric constant along the c axis, εc, shows a broad peak with a value of about 230 at a temperature, Tc+9.8 K, with a remarkable deviation from the Curie-Weiss law. No dielectric loss was found at 330 Hz above or below Tc. It was determined by both X-ray and piezoelectric examinations that the crystal at room temperature belongs to the space group of R3 with the unit cell parameters a= 16.625 Å and c=5.566 Å. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.