Capacitorlike metal/metal oxide/metal structures are widely used as resistive switching cells and are utilized in resistive random access memories. Recently, it has been demonstrated that they also perform well as gas sensors. In this work, we have merged the gas sensing and resistive switching capabilities of the capacitorlike Pt/TiO₂/Pt structures to constitute a simple device which works as a gas-triggered thyristorlike switch and as a gas sensor with a built-in memory.

Zirconium diboride (ZrB2) represents a promising hard coating material for demanding high-temperature applications and could provide an excellent basis for fine-tuning mechanical properties via the concept of alloying. Here, combining density functional theory and experiments, we investigate the effect of aluminum alloying on thermally induced structure evolution and mechanical properties of α-structured Zr1 − xAlxB2 + Δ. Ab initio calculations predict a strong tendency for spinodal phase separation of hexagonal Zr1 − xAlxB2 solid solution into isostructural binaries. Experimental results confirm predictions of the insolubility of aluminum in the ZrB2 phase when the structure of magnetron co-sputtered Zr0.72Al0.28B2.64 films with an aluminum content of 8 at. % has a nanocomposite character consisting of hexagonal α-ZrB2 nanocolumns surrounded by an amorphous Al-rich tissue phase. The films are structurally stable up to 1100 °C but out-diffusion of Al atoms from boundary regions during annealing was observed. Al alloying causes a significant decrease in hardness when the hardness of the reference as-deposited ZrB2.2 and Zr0.72Al0.28B2.64 is 39 and 23 GPa, respectively. Low hardening effect in ternaries was observed after annealing at 1000 °C when the hardness increased from 23.5 to 26.5 GPa due to the locally increased concentration of point defects at the boundaries of the nanocolumns and Al-rich tissue phases. Young's modulus decrease from 445 (ZrB2.2) to 345 GPa (Zr0.72Al0.28B2.64) indicates a change in the mechanical response of the ternary film toward more ductile behavior.

The use of silver-based antimicrobial materials has been growing recently. Considering the threat of developing silver-resistant bacteria, it is essential to address the endurance of such materials and the amount of silver released into the environment. Here we report on a durable, antibacterial Ag/TiB_x nanocomposite coating prepared by conventional magnetron sputtering. The coating consists of fine Ag clusters embedded in extremely hard, wear-resistant overstoichiometric TiB_x, which serves as a protective matrix. The highest E. coli growth inhibition of 97% is observed for the coating containing 24 at.% of Ag. A strong antibacterial effect is also maintained after 45 days of immersion in the Luria–Bertani + 5% HNO₃ solution. Despite a marked hardness decrease from 40 GPa for TiB_x to 6.4 GPa for Ag/TiB_x with 28 at.% of Ag, the coating maintains a good specific wear rate of 6 × 10⁻⁵ mm³/Nm. Moreover, the addition of Ag, which acts as a solid lubricant, decreases the coefficient of friction from 0.77 to 0.35, even at room temperature. Thanks to the combination of antibacterial properties and enhanced wear resistance, such material can find application as a protective coating for cutlery, door handles, water taps, and other daily-used objects in public areas.

Hexagonal ZrB₂ belongs to the group of ultra-high temperature ceramics representing an important class of materials with the potential to meet the high demands of today’s industry. However, this potential is limited by inherent brittleness and poor tribological properties. Here, the combination of density functional theory and experiment is used to investigate the effect of silver alloying on the mechanical and tribological properties of hexagonal ZrB₂ thin films. Calculations indicate strong insolubility of Ag atoms in the ZrB₂ metal sublattice and a significant effect on the mechanical properties, pointing out an improvement in ductility and tribological properties but at the cost of reduced hardness. The experiments confirmed the theoretical predictions of the strong insolubility of silver, where the magnetron-sputtered Zr_1−xAg_xB_2+Δ films form a segregated nanostructure consisting of separated hexagonal ZrB₂ and cubic Ag phases. With increased Ag content, values of Young’s modulus decrease from E^ZrB2.31 = 375 GPa to E^{Zr0.26Ag0.74B0.89} = 154 GPa, followed by a decrease in hardness from H^ZrB2.31 = 30 GPa to a value of H^{Zr0.26Ag0.74B0.89} = 4 GPa. The suppression of crack formation is also shown with the material flow around cube corner indents, indicating enhanced ductility. The improvement of tribological properties was also confirmed when the coefficient of friction (COF) was reduced from COF^ZrB2.31 ~0.9 to a value of COF^{Zr0.26Ag0.74B0.89} ~0.25 for all counterpart materials—steel (100Cr6), Si₃N_4, and WC/Co.