Evaluation of Potential Function of Core-Shell Model for PbTiO3 Ferroelectric Material and Its Application for Polarization Calculation

In this study, the core-shell model is used to calculate the electric polarization for PbTiO3 ferroelectric material, in which, the interaction potential functions among atoms are determined by the fitting method based on the results from the first principle calculation. The investigations obtained show that the remnant polarization increases under tension and decreases under compression. The remnant polarization decreases with increasing the temperature. The phase transition from the ferroelectric phase to the paraelectric phase is determined at 605K and can occur at lower temperatures of 0K, 300K, 400K, 500K if the compression strain are 8%, 6%, 5%, 2%, corresponding. The hysteresis loop shrinks as the temperature increases and degrades into a curve at the temperature of 605K.

Beam-foil measurements of lifetimes of energy levels belonging to Sn III and Sn IV

Beam-foil intensity decay curves for transitions in the wavelength range 750–5250 Å are used to derive the lifetimes of the 6s1S, 5p1P, 6p1P, 5d1D, 6d1D, 5p21D, 4f1F, 6s3S, 6p3p, 5p23p, 5d3D, 6d3D, and 4f3F levels of Sn III, and of the 6s2S, 5p2P, 6p2P, 5d2D, 6d2D, 4d95 s22D, and 4f2F levels of Sn IV. The arbitrarily normalized decay-curve analyses are used for most levels. Good agreement is found between experiment and a recent (relativistic Hartree–Fock + core-polarization) calculation for the resonance transition in low-Z members of the Cd 1 isoelectronic sequence, but the experimental f values are found to lie systematically about 20% above the theoretical trend obtained from a similar calculation for the Ag I sequence. Configuration interaction is found to produce very different lifetimes for the two 4d95s22D levels of Sn IV, and the energy of the J = 3/2 level is determined to be 177 060 ± 50 cm−1.

Electric dipole transitions from the 11.08 and 9.15 MeV levels in 17O

In the 13C(α, γ)17O reaction, measurements of E1 transition strengths from the 11.078 and 9.148 MeV (Jπ = 1/2−) levels to the 0.871 MeV level give (10.4 ± 1.6) × 10−3and (2.4 ± 0.5) × 10−3 e2 fm2, respectively. The ratio of these transition strengths results in a polarization charge epol ≈ −0.6. The E1 transition strength from the 11.078 MeV level is in excellent agreement with the core-polarization calculation of Towner and Hardy. The asymmetry for the corresponding isovector E1 transitions in 17O and 17F is found to be [Formula: see text], comparable in magnitude with the asymmetry for the analogous [Formula: see text] decays of 17N and 17Ne.