Process for producing high purity silicon nitride by the direct reaction between elemental silicon and nitrogen-hydrogen liquid reactants
A process is disclosed for producing, at a low temperature, a high purity reaction product consisting essentially of silicon, nitrogen, and hydrogen which can then be heated to produce a high purity alpha silicon nitride. The process comprises: reacting together a particulate elemental high purity silicon with a high purity nitrogen-hydrogen reactant in its liquid state (such as ammonia or hydrazine) having the formula: N[sub n]H[sub (n+m)] wherein: n=1--4 and m=2 when the nitrogen-hydrogen reactant is straight chain, and m=0 when the nitrogen-hydrogen reactant is cyclic. High purity silicon nitride can be formed from this intermediate product by heating the intermediate product at a temperature of from about 1200--1700 C for a period from about 15 minutes up to about 2 hours to form a high purity alpha silicon nitride product. The discovery of the existence of a soluble Si-N-H intermediate enables chemical pathways to be explored previously unavailable in conventional solid state approaches to silicon-nitrogen ceramics. 1 figure.
- Assignee:
- Dept. of Energy, Washington, DC (United States)
- Patent Number(s):
- US 4935214; A
- Application Number:
- PPN: US 7-380695
- OSTI ID:
- 7019717
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AMMONIA
CERAMICS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
ELEMENTS
HYDRAZINE
HYDRIDES
HYDROGEN COMPOUNDS
NITRIDES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
PNICTIDES
REACTION INTERMEDIATES
SEMIMETALS
SILICON
SILICON COMPOUNDS
SILICON NITRIDES
SOLUBILITY
SYNTHESIS