Synthesis of hafnium nanoparticles and hafnium nanoparticle films by gas condensation and energetic deposition

Sc, Zr, Hf, and Mn Metal Nanoparticles: Reactive Starting Materials for Synthesis Near Room Temperature

Zerovalent scandium, zirconium, hafnium, and manganese nanoparticles are prepared by reduction of ScCl3, ZrCl4, HfCl4, and MnCl2 with lithium or sodium naphthalenide in a one-pot, liquid-phase synthesis. Small-sized monocrystalline nanoparticles are obtained with diameters of 2.4 ± 0.2 nm (Sc), 4.0 ± 0.9 nm (Zr), 8.0 ± 3.9 nm (Hf) and 2.4 ± 0.3 nm (Mn). Thereof, Zr(0) and Hf(0) nanoparticles with such size are shown for the first time. To probe the reactivity and reactions of the as-prepared Sc(0), Zr(0), Hf(0), and Mn(0) nanoparticles, they are exemplarily reacted in the liquid phase (e.g., THF, toluene, ionic liquids) with different sterically demanding, monodentate to multidentate ligands, mainly comprising O-H and N-H acidic alcohols and amines. These include isopropanol (HOiPr), 1,1'-bi-2-naphthol (H2binol), N,N'-bis(salicylidene)ethylenediamine (H2salen), 2-mercaptopyridine (2-Hmpy), 2,6-diisopropylaniline (H2dipa), carbazole (Hcz), triphenylphosphane (PPh3), N,N,N',N'-tetramethylethylenediamine (tmeda), 2,2'-bipyridine (bipy), N,N'-diphenylformamidine (Hdpfa), N,N'-(2,6-diisopropylphenyl)-2,4-pentanediimine ((dipp)2nacnacH), 2,2'-dipydridylamine (Hdpa), and 2,6-bis(2-benzimidazolyl)pyridine (H2bbp). As a result, 22 new compounds are obtained, which frequently exhibit a metal center coordinated only by the sterically demanding ligand. Options and restrictions for the liquid-phase syntheses of novel coordination compounds using the oxidation of base-metal nanoparticles near room temperature are evaluated.

Plate-Like Colloidal Metal Nanoparticles

The pseudo-two-dimensional (2D) morphology of plate-like metal nanoparticles makes them one of the most anisotropic, mechanistically understood, and tunable structures available. Although well-known for their superior plasmonic properties, recent progress in the 2D growth of various other materials has led to an increasingly diverse family of plate-like metal nanoparticles, giving rise to numerous appealing properties and applications. In this review, we summarize recent progress on the solution-phase growth of colloidal plate-like metal nanoparticles, including plasmonic and other metals, with an emphasis on mechanistic insights for different synthetic strategies, the crystallographic habits of different metals, and the use of nanoplates as scaffolds for the synthesis of other derivative structures. We additionally highlight representative self-assembly techniques and provide a brief overview on the attractive properties and unique versatility benefiting from the 2D morphology. Finally, we share our opinions on the existing challenges and future perspectives for plate-like metal nanomaterials.

Combination of pulsed laser ablation and inert gas condensation for the synthesis of nanostructured nanocrystalline, amorphous and composite materials

A new instrument combining pulsed laser ablation and inert gas condensation for the production of nanopowders is presented. It is shown that various nanostructured materials, such as regular metallic, semiconducting, insulating materials, complex high entropy alloys, amorphous alloys, composites and oxides can be synthesized. The unique variability of the experimental set-up is possible due to the reproducible control of laser power (pulse energy and repetition rate), laser ablation pattern on the target, and experimental conditions during the inert gas condensation, all of which can be controlled and optimized independently. Microstructure analysis of the as-prepared composite and amorphous Ni₆₀Nb₄₀ nanopowders establishes the instrument's ability for the synthesis of materials with unique compositions and atomic structure. It is further shown that small variations of the synthesis parameters can influence materials properties of the final product, in terms of particle size, composition and properties. As an example, the laser power has been used to control the magnetic properties of amorphous Ni₆₀Nb₄₀ nanopowders. A few selected examples of the manifold possibilities of the new synthesis apparatus are presented in this report together with detailed structural characterization of the produced nanopowders.