Sodium Borohydride Reduction of Aqueous Silver-Iron-Nickel Solutions: a Chemical Route to Synthesis of Low Thermal Expansion–High Conductivity Ag-Invar Alloys

Abstract

Thermal management is a critical concern in the design and performance of electronics systems. If heat extraction and thermal expansion are not properly addressed, the thermal mismatch among dissimilar materials may give rise to high thermal stresses or interfacial shear strains, and ultimately to premature system failure. In this article, we present a chemical synthesis process that yields Ag-Invar (64Fe-36Ni) alloys with a range of attractive properties for thermal management applications. Sodium borohydride reduction of an aqueous Ag-Fe-Ni metal salt solution produces nanocrystalline powders, and conventional powder processing converts this powder to fine-grained alloys. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy, thermomechanical analysis, and electrical conductivity measurements; thermal conductivity is estimated using the Wiedemann-Franz law. Sintering of Ag-Fe-Ni powders leads to the formation of two-phase silver-Invar alloys with low coefficients of thermal expansion (CTEs) and relatively high electrical conductivities. A sample of 50Ag-50Invar exhibits a CTE of 8.76 lm/(mAE°C) and an estimated thermal conductivity of 236 W/(mAEK). The Ag-Invar alloys offer thermodynamic stability and tailorable properties, and they may help address the need for improved packaging materials.

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

“…The second method (B) corresponded to reducing gold with NaBH 4 . The sodium borohydride reduction of metal ions is a known chemical route to synthesize metal nanoparticles [325,326] 38. XP spectra of Rh 3d on titanate nanowire (A) and nanotube (B) with 1% Rh content (upper spectra) and 2% metal content (lower spectra).…”

Solid-state Thermoelectric Characteristics of NiII, FeII, CoII, and CuII Borohydrides

“…On the other hand, metal borides (M-Bs) [26][27][28][29][30][31][32][33][34] and metal borohydrides (M-BHs) [35][36][37][38][39][40][41][42][43][44][45] of p-, d-, and f-block elements have become in the spotlight as solid-state materials.…”

“…In general, MT-BHs are synthesized in various compositions, structures, and properties, as exemplified by their general chemical formula of Mx(BHn)y [36,38]. In this work, the desired MT-BHs were prepared by mixing the desired metal salt with fourfold excess of NaBH4 in a nonaqueous DMF/MeOH solvent system, Equation 5 [38][39][40][41][42][43][44][45]. This complex reaction process is generally affected by the MT:BH4¯ ratio, solvent, pH, and slow/rapid mixing of reagents.…”

“…This complex reaction process is generally affected by the MT:BH4¯ ratio, solvent, pH, and slow/rapid mixing of reagents. Due to the presence of traces of moisture, two main side reactions may be encountered during the reaction, the formation of metallic element (MT 0 ) and metal oxides /borates (MTO, MTBO3 Equation 6 [39,43,45]. To overcome these possible side reactions, our reactions were carried out in DMF/MeOH solvent mixtures using excess NaBH4.…”

Biogenic synthesis of a silver nanoparticle–SnZrMoP nanocomposite and its application for the disinfection and detoxification of water

“…The synthesis of AgNPs can be carried out by a number of techniques, like laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods. 9 However, the majority of routes for the synthesis of nanoparticles encompass the use of hazardous chemicals or high energy requirements. To overcome these demerits, biogenic nanoparticles synthesized from plant extracts without making use of any poisonous chemicals would be considered attractive for nanotechnology.…”