Patent ID: 7612006

Claim:
A sintered silicon nitride with a conductivity of higher than 10 −1 Ω −1 m −1 produced by (a) preparing a mixture, comprising 0.5 to 10 weight percent of rare-earth compounds in terms of oxide, 0.1 to 5 weight percent of aluminum oxide or its precursor, 0 to 5 weight percent of aluminum nitride, 0.1 to 5 weight percent of oxides of titanium group or other titanium group compounds in terms of equimolar titanium nitride wherein the titanium group compounds can be converted to nitrides of titanium group elements by sintering, and silicon nitride powder as a balance, and further comprising 0.3 to 12 weight percent of carbon nanotubes (CNT) relative to 100 weight percent of the foregoing mixture, wherein the silicon nitride powder has an average grain diameter of less than 1.0 μm and contains less than 1.7 weight percent of oxygen content and more than 90 weight percent of alpha phase type silicon nitride, and (b) sintering the mixture by a normal pressure sintering method or an ambient pressure sintering method.