High hardness improves the material’s load-bearing capacity, resulting in the enhancement of tribological properties. However, the high hardness is difficult to achieve for TiAlN coating due to the transformation of the close-packed structure from cubic to hexagonal and the increase in the grain size when the Al content is high. In the present study, the ultrahard TiAlN coatings (hardness > 40 GPa) are successfully developed by filtered cathodic vacuum arc technology to study the effect of nitrogen flux rate on tribological behaviors. The highest hardness of 46.39 GPa is obtained by tuning the nitrogen flux rate to achieve the regulation of Al content and the formation of nanocrystalline. The stable fcc TiAlN phase is formed via the solid-phase reaction under a high nitrogen concentration, and more aluminum atoms replace the titanium atoms in the (Ti, Al)N solid solution. The high Al content of the Ti_0.35Al_0.65N coating has a nanocrystalline structure and the average crystalline size is 16.52 nm. The TiAlN coating deposited at a nitrogen flux rate of 60 sccm exhibits the best properties of a combination of microhardness = 2972.91 Hv_0.5, H = 46.39 GPa, E = 499.4 Gpa, ratio H/E* = 0.093 and ratio H³/E*² = 0.403. Meanwhile, the TiAlN coating deposited at 60 sccm shows the lowest average friction coefficient of 0.43 and wear rate of 1.3 × 10⁻⁷ mm³ N⁻¹ m⁻¹ due to the best mechanical properties.

AlGaN/GaN high-electron-mobility transistors (HEMTs) with two different gate–drain distances (30 $\mathsf{\mu }$m and 10 $\mathsf{\mu }$m) were exposed to 1 MeV, 0.6 MeV, and 0.4 MeV protons at a fluence of 2.16 × 10¹² cm⁻². The gate–channel electron density and low-field mobility were obtained by measuring the capacitance–voltage characteristics and current–voltage characteristics. After proton irradiation, the gate–channel low-field electron mobility of the AlGaN/GaN HEMT with a 30 $\mathsf{\mu }$m gate–drain distance increases and that with a 10 $\mathsf{\mu }$m gate–drain distance decreases. It is studied and found that the mobility behavior is related to the polarization Coulomb field scattering, and the proton irradiation influences the intensity of the polarization Coulomb field scattering by changing the polarization/strain distribution in the barrier layer. The different gate–drain distances correspond to different variation trends of scattering intensity. The effect of 1 MeV protons on the barrier layer is smaller compared with 0.6 MeV and 0.4 MeV protons, so the mobility variation is smaller.

In this study, ion-beam-induced luminescence with 2 MeV H⁺ was used to excite YAG single crystals at different temperatures. Under several constant temperatures, the luminescence intensity of Yb²⁺ monotonically decreases with increasing fluence, eventually reaching approximately 35% of the initial intensity at a fluence of 3.5 × 10¹⁴ cm⁻². The nonmonotonic evolution behavior of Yb²⁺ luminescence intensity with temperature can be effectively described by the intermediate-state model under consecutive temperature variations. The presence of an intermediate state may be the primary cause of the negative thermal quenching of Yb²⁺ luminescence. Yb²⁺ luminescence intensity decreased to 60% of the initial intensity when the temperature was continuously varied in the 100–300 K range, although the peak position remained rather stable. The luminescence of Yb²⁺ exhibits good radiation resistance and thermal stability in the experimental temperature range.

In this paper, D_I defects are studied via experiments and calculations. The 2 MeV H⁺ is used to carry on an ion-beam-induced luminescence (IBIL) experiment to measure the in-situ luminescence of untreated and annealed 4H-SiC at 100 K. The results show that the luminescence intensity decreases rapidly with increasing H⁺ fluence, which means the losses of optical defect centers. In addition, the evident peak at 597 nm (2.07 eV) is the characteristic peak of 4H-SiC, and the weak peak between 400 nm and 450 nm is attributed to the D_I optical center. Moreover, the first-principles calculation of 4H-SiC is adopted to discuss the origin of D_I defects. The optical transition of the defect Si_C(C_Si)₂ from q = 0 to q = 1 is considered the experimental value of the D_I defect center.