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High‐temperature plasmonics deals with optically active nanostructures that can withstand high temperatures. A conventional approach relying on standalone noble metal nanoparticles fails to deliver refractory plasmonic nanomaterials, and an alternative route envisions metal nitrides. The main challenge remains the development of advanced synthesis techniques and the insight into thermal stability under real‐life application conditions. Here, hafnium nitride nanoparticles (HfN NPs) can be produced by gas aggregation using reactive magnetron sputtering, a technique with a small environmental footprint are shown. As‐deposited NPs are of 10 nm mean size and consist of stoichiometric, crystalline fcc HfN. They are characterized by optical absorption below 500 nm caused by interband transitions and in the red/near‐infrared (NIR) region due to intraband transitions and localized surface plasmon resonance (LSPR). The optical response can be engineered by tuning the NP composition as predicted by finite‐difference time‐domain (FDTD) calculations. Going beyond the state‐of‐the‐art, the HfN NP thermal stability is focued under ultrahigh vacuum (UHV) and in air. During UHV annealing to 850 °C, the NPs retain their morphology, chemical and optical properties, which makes them attractive in space mission and other applications. During air annealing to 800 °C, HfN NPs remain stable until 250 °C, which sets a limit for air‐mediated use. [ABSTRACT FROM AUTHOR]

In this communication, a new gas aggregation cluster source is introduced equipped with post cylindrical magnetron. The rotation of magnetic circuit improves the usage of cylindrical copper target in terms of its homogenous consumption. Copper nanoparticles were successfully synthesized. Their deposition rate fluctuates at slow rotations of magnetic circuit. Cyclic trapping and release of nanoparticles from electrostatic capture zones are likely responsible for this effect. The instabilities are not observed at higher rotation speeds. The argon flow is found to be very complex within the cluster source; however, it seems crucial for its operation. The efficiency of transport of nanoparticles and their size increase with gas flow. The highest values of deposition rate of around 19 mg/h are obtained. [ABSTRACT FROM AUTHOR]