fig3

Figure 3. A: Temperature dependence of relative dielectric permittivity (ε₃₃/ε₀) of the investigated single-crystal BTO sample measured at 1 kHz; B: calculated spherical map of bulk-free energy for C, T, O and R phases. The favored polarization vectors point toward regions with local energy minima (blue). The C phase represents a uniformly nonpolar state without distinct domains. R: Rhombohedral phases; O: orthorhombic; T: tetragonal; C: cubic; BTO: BaTiO₃.