A Complexed Precursor Approach to the Synthesis of Ternary Transition Metal Nitrides
- PDF / 2,176,644 Bytes
- 7 Pages / 414.72 x 648 pts Page_size
- 3 Downloads / 163 Views
a solution of Na 2MoO 4 "(H2 0) 2 .The alkali salt can be washed off and the hydrated mixed metal molybdate can be dried and then heat-treated in ammonia to form the ternary nitride [11]. Similarly, Herle et al. have synthesized layered LiWN 2 using the reaction of Li2 WO 4 with NH 3 at high temperature [12]. More traditional synthesis strategies include the nitridation of intermetallic compounds and solid state reactions between two metal compounds in ammonia or nitrogen [13,14]. Over the last few years, particularly with the advent of the sol-gel process, there has been considerable interest in investigating solution chemistry approaches to synthesize both oxide and non-oxide ceramic materials. The interest has been primarily due to the excellent mixing at a molecular level that is possible in solution. As a result, precursors can be generated which have clusters or molecular structural units that are identical to those found in the ultimate desired material. Consequently, diffusion distances are significantly reduced and materials which normally form at high temperature and require long reaction times can be synthesized with enhanced kinetics at low to moderate heat treatment temperatures. In a recent work, we have shown that by forming direct metal-anion bonds at the precursor stage, the final nonoxide can be synthesized with short, moderate temperature heat treatments [15]. In the present study we have extended this approach by synthesizing transition metal nitrides from complexed mixed metal organometallic precursors. The precursors are formed by hydrolyzing ethanolamine chelated metal species in solution. After filtering and drying, the precursors are heat treated in ammonia to form the final ternary nitride compound. Thus far, Ni3 Mo 3N, FeWN 2, and Ti 3AIN have been synthesized by this technique. The simplicity of the basic approach and the chelating strength of the alkanoamine family is expected to offer quite a bit of flexibility in processing, particularly with respect to the synthesis of multiple component nitrides. Additionally, it is expected that the processing conditions will have a large effect 127 Mat. Res. Soc. Symp. Proc. Vol. 410 01996 Materials Research Society
on the surface area, morphology, and final microstructure of the nitride material and may offer a means of controlling these microstructural aspects. EXPERIMENTAL PROCEDURE 1. Materials and Equipment All inorganic metal chlorides were used as received: AICl 3 (99.99%, Aldrich), FeCIE2 4H2 0 (99.995%, Fisher Scientific), MoC15 (99.9%, Aldrich), NiCIE2 6H 2 0 (99.9999%, Aldrich), TiCI4 (99.9%, Aldrich), and WCI6 (99%, Aldrich). HPLC grade acetonitrile (Fisher Scientific) and ethanolamine (99%, Sigma) were used without further purification. The water used for hydrolysis was doubly distilled and de-ionized to a resistivity of 18.3 Mohm-cm or greater. Electronic grade ammonia (Matheson Gas) was used for the pyrolysis and ammonolysis treatments of the mixed metal precursors. All chemical manipulations were conducted in an argon filled glov
Data Loading...
