A systematic study of neutron-rich even-even Fe isotopes with a neutron number from 32 to 42 is carried out by using the projected shell model. Calculations are performed up to the spin I = 20 state. Irregularities found in the yrast spectra and in B (E2) values are discussed in terms of neutron excitations to the high-j orbital g 9/2 . Furthermore, the neutron two-quasiparticle structure of a low-K negative-parity band and the proton two-quasiparticle structure of a high-K positive-parity band are predicted to exist near the yrast region. Our study reveals a soft nature for the ground state of N ≈ 40 isotopes and emphasizes the important role of the neutron g 9/2 orbital in determining the structure properties for both low-and high-spin states in these nuclei.
n-type Mg2(Si0.4Sn0.6)Bix (0 ≤ x ≤ 0.04) solid solutions with minute amounts of Bi were prepared by induction melting, melt spinning (MS), and spark plasma sintering (SPS) method, namely the non-equilibrium technique MS-SPS, using bulks of Mg, Si, Sn, Bi as raw materials; the phase components, microstructures as well as the thermoelectric properties were systematically investigated. The multiple localized nanostructures within the matrix containing nanoscale precipitates and mesoscale grains were formed, resulting in remarkably decreasing of lattice thermal conductivities, particularly for samples with the nanoscale precipitates having the size of 10–20 nm. Meanwhile, the electrical resistivity was reduced and the Seebeck coefficient was increased by Bi-doping, causing improved electrical performance for the Mg2(Si0.4Sn0.6)Bix (0 ≤ x ≤ 0.04) compounds. The dimensionless figure of merit ZT was significantly improved and the maximum value reaches 1.20 at 573 K for the Mg2(Si0.4Sn0.6)Bi0.03 sample, greatly higher than that of the non-doped samples.
The neutron and proton odd-even mass differences are systematically studied with HartreeFock+BCS (HFBCS) calculations with Skyrme interactions and an isospin dependent contact pairing interaction. The strength of pairing interactions is determined to reproduce empirical odd-even mass differences in a wide region of mass table. By using the optimal parameter sets for proton and neutrons, we perform global HF+BCS calculations of nuclei and compare with experimental data. The importance of isospin dependence of the pairing interaction is singled out for odd-even mass differences in medium and heavy isotopes. The proton and neutron radii are studied systematically by using the same model.
It has been found that high-order deformation (e.g. β 6 ) can have important effects on the structures of superheavy nuclei. In the present work, we investigate octupole deformation effects on superheavy nuclei with an improved potential-energy-surface (PES) calculation by including reflection-asymmetric deformations in a space of (β 2 , β 3 , β 4 , β 5 ). The calculations give various deformations including highly deformed (β 2 ≈ 0.4) and superdeformed (β 2 ≈ 0.7) shapes. The octupole-deformation degree of freedom mainly affects the fission barrier beyond the second minimum of PES. Experimentally, octupole correlation manifests itself in atomic nuclei usually with enhanced E1 transitions connecting interleaved positive and negative-parity bands, which is similar to the rotational bands observed in reflectionasymmetric molecules [1]. Such correlation originates from the coupling of a pair of single-particle orbitals close to the Fermi Surface and having ΔN = 1, Δl = 3 and Δ j = 3. superdeformed minima are soft with respect to octupole deformations in A∼40, A∼150 and A∼190 mass regions [6][7][8]. This is because the single-particle spectrum at superdeformations favors octupole excitations due to the presence of intruder states [2]. Experiments have identified some octupolevibrational states and strong E1 transitions which are expected to connect these vibrational levels to the lowest SD band [7][8][9][10].With the development of the radioactive beam facility, heavy-ion accelerator and highly-effective detector systems [11,12], great progress has been made recently in nuclear physics including the synthesis of superheavy nuclei [13][14][15]. The deformations of superheavy nuclei are interesting. Superdeformed prolate [16][17][18] and superdeformed oblate [19] shapes have been predicted. In our previous works [20,21], we discussed the β 6 effects in superheavy nuclei [20] and the β 3 effects on high-K states at the second well of actinide nuclei [21]. In the present paper, using an improved potentialenergy-surface (PES) with the inclusion of reflectionasymmetric β 3 and β 5 deformations, we systematically calculate 248−264
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