Prediction of potential high-temperature superconductivity in ternary Y-Hf-H compounds under high pressure.

Compressed ternary alloy superhydrides are currently considered to be the most promising competitors for high-temperature superconducting materials. Here, the stable stoichiometries in the Y-Hf-H ternary system under pressure are comprehensively explored in theory and four fresh phases are predicted: Pmna-YHfH6 and P4/mmm-YHfH7 at 200 GPa, P4/mmm-YHfH8 at 300 GPa and P-6m2-YHfH18 at 400 GPa. The four Y-Hf-H ternary phases are thermodynamically and dynamically stable at corresponding pressure. In addition, structural features, bonding characteristics, electronic properties, and superconductivity of the four ternary Y-Hf-H phases are systematically calculated and discussed. As the hydrogen content and the density of states of H atoms at the Fermi level increase, the superconducting transition temperatures (Tc) of Y-Hf-H system are significantly enhanced. The P-6m2-YHfH18 with high hydrogen content exhibits a high calculated Tc value of 130 K at 400 GPa.

Thermally tunable broadband metamaterial absorbers based on ionic liquids.

In this paper, we propose an interesting thermally tunable broadband metamaterial absorber based on ionic liquids at the microwave band, which has distinct modulation characteristics in different frequency bands. Numerical simulation results show that the absorption decreases with the increase of temperature in the low-frequency band from 2-10GHz, which decreases to 60% at 100 °C. Meanwhile, the absorption increases with the increase in temperature in the high-frequency band from 25GHz to 48GHz. In addition, the absorber still has good broadband absorption without the metal substrate, and the absorption reaches more than 80% in the frequency band of 13.96-34.10GHz. As an all-dielectric metamaterial absorber, its absorption increases with the increase in temperature, which reaches more than 90% in the range of 20.44-50GHz at 100 °C. At last, the designed metamaterial absorbers have been fabricated based on ionic liquids, and experimental results are presented to demonstrate the validity of the proposed structure. Furthermore, the simple design and wide frequency tuning range of the absorbers can promise a great potential application in sensors, detection, and frequency-selective thermal emitters.

[Study on the Photo-thermal Effect of Gold Nanorods Irradiated with Near Infrared Region Laser in Different Conditions].

This article explores the possible influencing factor and regular pattern of temperature rise induced by photo-thermal effect of gold nanorods when irradiated with near infrared region (NIR) laser. We used transmission electron microscope and UV-Vis-NIR spectrometer to characterize gold nanorods, then used 808 nm NIR laser with different power to irradiate the gold nanorods in different conditions and measured the temperature of the above solution. The higher the concentration of gold nanorods, the faster the temperature rose and the bigger its amplitude was. When the concentration of gold nanorods was fixed, the relation between power of laser and amplitude of temperature rise was linear. Temperature rise was also related to the shape of container. It could be concluded that amplitude of temperature rise of gold nanorods reaction system was related with concentration of the particles, irradiated power and shape of the container, so that we could control the temperature easily by regulating the irradiated power size of NIR laser in the experiments.