Abstract
The dielectric constant of BaTiO3 single crystals in the region above the 120°C Curie point has been measured at several frequencies in the range from 1 kc/sec to 2000 Mc/sec. In addition, the B coefficient in Devonshire's equation for the free energy has been studied at 500 Mc/sec. It is shown that the crystal is completely clamped with respect to the measuring field at 500 Mc/sec so that the coefficient of the P4 term in Devonshire's equation is positive and agrees with the expected theoretical result of BFC=2.23×1013 cgs unit.