Diamond–copper composites, due to their exceptional thermal conductivity, hold significant potential in the field of electronic device thermal management. Hot-press sintering is a promising fabrication technique with industrial application prospects; however, the thermal conductivity of composites prepared by this method has yet to reach optimal levels. In this study, tungsten was deposited on the surface of diamond particles by magnetron sputtering as an interfacial transition layer, and hot-press sintering was employed to fabricate the composites. The findings reveal that with prolonged annealing time, tungsten gradually transformed into W2C and WC, significantly enhancing interfacial bonding strength. When the diamond volume content was 50% and the interfacial coating consisted of 2 wt.% W, 92 wt.% WC, and 6 wt.% W2C, the composite exhibited a thermal conductivity of 640 W/(m·K), the highest value reported among hot-press sintered composites with diamond content below 50%. Additionally, the AMM (Acoustic Mismatch Model) and DMM (Diffusion Mismatch Model) models were utilized to calculate the interfacial thermal conductance between different phases, identifying the optimal interfacial structure as diamond/W2C/WC/W2C/Cu. This composite material shows potential for application in high-power electronic device cooling, thermal management systems, and thermoelectric conversion, providing a more efficient thermal dissipation solution for related devices.
Tb3+-activated LTA zeolite-derived boro-aluminosilicate glass samples with a composition of xTb2O3-68(Na2O-Al2O3-SiO2)–32B2O3 (x = 0.2, 1.0 and 10 extra wt%) were prepared using the melt-quenching method. The emission spectra recorded upon ultraviolet (UV) excitation with two different wavelengths of 193 and 378 nm showed blue light (5D3 to 7FJ=6,5,4 and 5D4 to 7F6 transitions of Tb3+) and green light (5D4 to 7F5 transition of Tb3+) emissions with comparable intensities up to a Tb3+ concentration of 10 extra wt%. Of note, the mean decay times of the green luminescence of the glass samples were relatively fast (<20 μs). The synthesized glass has potential in applications concerning UV imaging, UV detection, and plasma display panels.
Electrohydrodynamic (EHD) printing is an advanced high-precision printing technology suitable for manufacturing micro- and nanostructures in fields such as transistors, sensors, and electroluminescent devices. However, its printing resolution is influenced by various factors, including voltage conditions, printing distance, and ink properties. For a specific printing ink, this study investigates the effects of direct current (DC) voltage mode and bias pulse voltage mode on printing resolution, and further analyzes the impact of bias pulse voltage parameters on the printing characteristics of silver lines. Experimental results show that print width increases with voltage amplitude; compared to the DC mode, the modulated pulse mode enables higher printing resolution. Moreover, under pulse mode, printing width exhibits a non-monotonic variation with increasing pulse frequency, first decreasing and then increasing. These findings provide theoretical basis and technical guidance for optimizing EHD printing processes to achieve high-precision and high-uniformity fabrication of micro/nano-structure.
Applying an appropriate bias voltage during direct current magnetron sputtering can optimize the valence state, facilitate phase transition, and improve the performance of deposited VO 2 film.
This study examined the effects of gadolinium (Gd) doping and the resulting oxygen vacancies on the microstructure and phase-transition characteristics of VO2 thin films.