  Chen Ang, Bhalla and Cross [Phys. Rev. B 64, 184104 (2001)] have studied the
low-frequency (20 Hz -- 100 kHz) dielectric dispersion of the KTaO3 crystal
under a dc electric field. Performing fits of the electric field dependence
they came to conclusion that an appreciable contribution to the dielectric
permittivity originates from polar clusters. In this Comment we show that the
dielectric permittivity at low frequencies (100 Hz -- 1 MHz) equals to that in
the THz region, close below the polar phonon response. This excludes the
possibility of any appreciable dielectric dispersion due to polar clusters. In
addition, we demonstrate that correct treatment using
Landau-Ginzburg-Devonshire theory allows to fit the electric field dependence
of the dielectric constant without assuming any polarization mechanism besides
the polar phonon modes.
