Phase separation in ferroelectrics with blurred phase transition

Phase separation in ferroelectric and superconducting crystals has been established by some scientists. Within electron plasma model, complex crystals of Aa Bb Сc Dd as a result of phase separation into four subsystems: ferroelectric crystals with blurred phase transition are considered. During the phase transition in the Aa Bb Сc Dd crystals, the valence bond breaking associated with the crystal lattice destruction. It is caused by the balance energies of the Aa-Bb-Cc-Dd and A-A, B-B, C-C, D-D bonds. The basic principle of the phase transition is caused by bonds being broken and dumbbell configurations of atoms are formed. The pairing of electrons is guided by a plasma mechanism. Free electrons couple to lower system energy. When molecules are formed from individual atoms by dumbbell configuration, energy is released. The energy balance is caused by a change in the distances between atoms A-A, B-B, C-C, D-D, with decreasing temperature. It is necessary that in the phase transition region the total square plasma energy of the formed quasi-molecules is significantly greater than the square plasma energy of the original crystal. This is the condition for the phase transition in the crystals Aa Bb Сc Dd. 2 Aa Bb Сc Dd = a●A2 + b●B2 + c●C2 + d●D2. During phase separation of a polyatomic crystal, a multigap energy system is formed. A method for finding the phase transition temperature of a crystal was proposed. q (abcd) = 2●β●Φ2 (abcd) / (a●Φ2 (a) + b●Φ2 (b) + c●Φ2 (c) + d●Φ2 (d)) Parameters are square Φ2 (M, ρ, s, q, β), square Φ2 (аbcd), square Φ2 (а), square Φ2 (b), square Φ2 (c), square Φ2 (d) are square electron energy in square eV2 crystal abcd, a, b, c, d, respectively, Tc is the phase transition temperature, ρ is density, s is valence electron number, M is molecular (atomic) mass, q and β are interaction constants. The parameters of electron-dense plasma in ferroelectric crystals with blurred phase transition Pb Mg1/3 Nb2/3 O3, Pb Ni1/3 Nb2/3 O3, Pb Ni1/3 Ta2/3 O3, Pb Co1/3 Nb2/3 O3 were calculated. Within electron plasma model, superconductivity at 0- 8 K was discovered in complex ferroelectrics with diffuse phase transition.