  Dielectric and magnetic properties of Eu0.5Ba0.25Sr0.25TiO3 are investigated
between 10 K and 300 K in the frequency range from 10 Hz to 100 THz. A peak in
permittivity revealed near 130 K and observed ferroelectric hysteresis loops
prove the ferroelectric order below thistemperature. The peak in permittivity
is given mainly by softening of the lowest frequency polar phonon (soft mode
revealed in THz and IR spectra) that demonstrates displacive character of the
phase transition. Room-temperature X-ray diffraction analysis reveals cubic
structure, but the IR reflectivity spectra give evidence of a lower crystal
structure, presumably tetragonal I4/mcm with tilted oxygen octahedra as it has
been observed in EuTiO3. The magnetic measurements show that the
antiferromagnetic order occurs below 1.8 K. Eu0.5Ba0.25Sr0.25TiO3 has three
times lower coercive field than Eu0.5Ba0.5TiO3, therefore we propose this
system for measurements of electric dipole moment of electron.
