The pressure-temperature phase diagram of BaTiO3: a macroscopic description of the low-temperature behaviour

摘要: The pressure–temperature phase diagram of BaTiO3 has been investigated using a modification the standard Landau potential to take account quantum saturation order parameter at low temperatures. calculated agrees well with experiment for cubic–tetragonal and tetragonal–orthorhombic transitions, but underestimates orthorhombic–rhombohedral transition temperature somewhat. (θS = 160 K) is sufficiently high that expected critical point not observed experimentally. Instead, each boundary bends sharply down, so four crystalline structures stability field increasing pressure 0 K.