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High-spin states of 156 Yb have been studied via the 144 Sm( 16 O,4n) 156 Yb fusion-evaporation reaction at beam energy 102 MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. In the present work, the negative-parity sequence above the 25 − state was found to be irregular and fragment into many parallel branches. This pattern may related to the excitation from the nucleon in the Z = 64, N = 82 core. The characteristics of alignment plot and E-GOS curve for the positive-parity yrast sequence in 156 Yb indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. Based on a systematic summary of the available experimental alignments for the even-A 156,158,160,162,164 Yb isotopes, the structural evolutions induced by the increase in angular momentum, as well as by the change in neutron numbers, in these even-A Yb isotopes have been discussed in comparison with the cranked Woods-Saxon-Strutinsky calculations by means of total-Routhian-surface (TRS) methods.

With the development of hypersonic vehicles technology, ceramic based radome materials are highly demanded due to their high operating temperatures, good dielectric properties, and high mechanical properties. Although α-SiAlON is an ideal material for radome application, its intrinsic low transmittance and high thermal conductivity limit its application. Herein, we prepared Y-α-SiAlON porous ceramics through tert-butanol gel-casting using self-synthesised α-SiAlON powder. Y-α-SiAlON porous ceramics exhibited a uniform micron-level connected pore structure with a porosity of 44.2%-58.6%. The real part of permittivity was 3.13-4.18 (8.2-12.4 GHz), which decreased significantly with increasing porosity. The wave transmittance of the sample with a porosity of 58.6% could exceed 80% in the thickness range of 6-10 mm. The thermal conductivity maintained at a low level of 1.38-2.25 W•m -1 •K -1 owing to the introduction of the pore structure. The flexural strength was 44.75-88.33 MPa, which may be increased by rod-like α-SiAlON grains. The results indicate that the prepared Y-α-SiAlON porous ceramics meet the requirements of high-temperature wave-transmitting materials for radome application.

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