Domain Clamping Effect in Barium Titanate Single Crystals

We have found that the dielectric constant of good single crystals of barium titanate decreases as the average polarization is decreased by means of an electric field. This has been interpreted as being due to a domain clamping effect arising from the multidomain situation in the crystal that accompanies the reduction in polarization. These measurements give a value for the coefficient of coupling of 0.50 which is in agreement with Caspari and Merz's value of $d_{33}$ and our measurement of $S_{33}$.. The coupling coefficient has been studied as a function of temperature using this clamping effect.