Electrostriction and Stress-Induced Ferroelectricity in KTaO 3

The dielectric constant of KTaO 3 has been measured as a function of the applied uniaxial stress normal to the (100), (110) and (111) faces. Under the stress normal to (100) or (110), the induced ferroelectric phase transition has been observed at liquid-helium temperatures. From the analysis of the stress dependence of the dielectric constant in the paraelectric phase, the electrostrictive constants for this crystal have been determined as Q 11 =9.69±0.7, Q 12 =-2.55±0.2 and Q 44 =3.3±2.6 in 10 -13 cgs at 4.2 K. Their magnitude was found to decrease at the rate of 8×10 -4 in 10 -13 cgs/K with increase of temperature. Characteristics of the dielectric constant in the stress-induced ferroelectric phase are also discussed.