12034-80-9Relevant articles and documents
Simultaneous synthesis and consolidation of nanostructured NbSi2-Si3N4 composite from mechanically activated powders by high-frequency induction-heated combustion
Park, Hyun-Kuk,Shon, In-Jin,Yoon, Jin-Kook,Doh, Jung-Mann,Ko, In-Yong,Munir
, p. 560 - 564 (2008)
Dense nanostructured 4NbSi2-Si3N4 composite was synthesized by high-frequency induction-heated combustion synthesis (HFIHCS) method within 1 min in one step from mechanically activated powders of NbN and Si. Simultaneous combustion synthesis and densification were accomplished under the combined effects of an induced current and mechanical pressure. Highly dense 4NbSi2-Si3N4 composite with relative density of up to 98% was produced under simultaneous application of a 60 MPa pressure and the induced current. The average grain size and mechanical properties (hardness and fracture toughness) of the composite were investigated.
Speier, W.,Kumar, L.,Sarma, D. D.,Groot, R. A.de,Fuggle, J. C.
, (1989)
Shibata, T.,Gibbons, J. F.,Sigmon, T. W.
, p. 566 - 569 (1980)
Silicide coating on refractory metals in molten salt
Tatemoto,Ono,Suzuki
, p. 526 - 529 (2005)
For better oxidation resistance of refractory metals in air, the electroless coating of silicide in the molten salt was developed in open air at 973-1173 K. The molten salt consists of NaCl, KCl, Na2SiF6 and Si powder, where the prop
Solid state metathesis synthesis of metal silicides; reactions of calcium and magnesium silicide with metal oxides
Nartowski, Artur M.,Parkin, Ivan P.
, p. 187 - 191 (2002)
Reactions of transition metal oxides (V2O3, V2O5, Nb2O5, LiNbO3, Ta2O5, LiTaO3, MoO3 and Li2MoO4) with lithium silicide (Li2Si) and calcium silicide-magnesium silicide mix (CaSi2, Mg2Si) could be initiated by grinding, flame, filament or bulk thermal methods to produce a range of single phase transition metal silicides (VSi2, NbSi2 and TaSi2) in good yields (approximately 90%). The silicides were characterised by X-ray powder diffraction, scanning electron microscopy (SEM), energy dispersive analysis by X-rays (EDAX), electron probe, FTIR and microelemental analysis.
NbSi2 coating on niobium using molten salt
Suzuki, Ryosuke O.,Ishikawa, Masayori,Ono, Katsutoshi
, p. 280 - 285 (2002)
For obtaining better oxidation resistance of niobium in air, a niobium silicide was non-electrolytically deposited onto niobium from the molten salt, where a disproportional reaction occurs between Na2SiF6, SiO2, and Si. A single phase of NbSi2 was formed with a homogeneous thickness of about 10 μm above 1073 K. The oxidation resistance of pure niobium with this coating layer was improved. During the oxidation at the high temperatures, Nb5Si3 was formed at the interface between the Nb substrate and the NbSi2 layer. Due to this intermediate layer formation, the oxidation resistance became better than for pure NbSi2.
Phase relations in the Nb-Sb-Si and Nb-Sb-P systems
Lomnytska, Ya. F.
, p. 722 - 727 (2010)
Phase relations in the systems Nb-Sb-Si (0-70 mol % Sb) and Nb-Sb-P (0-50 mol % P) have been studied by X-ray diffraction, and the 1070-K isothermal sections of their phase diagrams have been constructed. The existence of the compound NbSbSi (PbFCl structure) has been confirmed. Both systems contain a few substitutional solid-solution series: Nb3(Sb,Si) and Nb 3(Sb,P) (Cr3Si structure, limiting compositions Nb 3Sb0.55Si0.45 and Nb3Sb 0.8P0.2), Nb3(Si,Sb) and Nb3(P,Sb) (Ti3P structure, limiting compositions Nb3Si 0.6Sb0.4 and Nb3P0.5Sb 0.5), Nb(P,Sb) (NbAs structure, limiting composition NbP 0.8Sb0.2), and Nb(Si,Sb)2 (CrSi2 structure, limiting composition NbSi1.65Sb0.35). Phase equilibria in related systems are analyzed.
Alkali metals extraction reactions with the silicides Li15Si4 and Li3NaSi6: Amorphous Si versus allo -Si
Zeilinger, Michael,Jantke, Laura-Alice,Scherf, Lavinia M.,Kiefer, Florian J.,Neubüser, Gero,Kienle, Lorenz,Karttunen, Antti J.,Konar, Sumit,H?ussermann, Ulrich,F?ssler, Thomas F.
, p. 6603 - 6612 (2015/02/19)
The silicides Li15Si4 and Li3NaSi6 were subjected to chemical extraction of the alkali metal component by liquid ammonia and ethanol, respectively, which after washing yielded black powders of amorphous silicon. The investigated reactions are interesting with respect to both the formation of novel Si modifications and the delithiation process in Si anode materials. The products termed a-Si (from Li15Si4) and a-allo-Si (from Li3NaSi6) were characterized by a combination of methodologies (X-ray diffraction, transmission electron microscopy, differential thermal analysis, Raman, atomic absorption, and energy-dispersive X-ray spectroscopy) which revealed (i) a porous microstructure for a-Si built from spherically shaped particles with sizes around 10 nm, (ii) partial surface oxidation of both materials and (iii) the presence of nanocrystalline Si in both materials. The result of the protic oxidation of Li3NaSi6 is at variance with earlier findings reporting the formation of a crystalline bulk allotrope of silicon (allo-Si) from the topotactic combination of silicon layers present as polyanions in Li3NaSi6. Additionally, quantum chemical calculations show that silicon layers in Li3NaSi6 cannot combine to energetically favorable allotropic forms of Si. This is different from Li7Ge12, where polyanionic germanium layers topotactically convert to the germanium allotrope m-allo-Ge upon oxidation.
