New insights into linear electrical properties of pressureless sintered SiC-MoSi2-AlN composites

Abstract Highly conductive SiC-MoSi 2 -AlN composites were fabricated by β-SiC, AlN and MoSi 2 powders with Y 2 O 3 additive via pressureless sintering. The effect of MoSi 2 content on the microstructure, mechanical and electrical properties of SiC-MoSi 2 -AlN composites was systematically investigated. A finer microstructure was obtained and electrical conductivity was enhanced with increasing MoSi 2 content. The impedance spectroscopy and potential-current measurements were implemented to figure out the electrical conduction mechanism. The introduction of MoSi 2 effectively reduced the Schottky barrier height at the grain boundary, and subsequently the U-I curves changed from nonlinear to linear electrical characteristics. The notable decrease in electrical resistivity was owing to the breakdown of grain boundaries and the formation of percolation paths. The percolation threshold was in the range of 0–5.44 vol% MoSi 2 , much lower than the reference value. The composites with 10 wt% MoSi 2 exhibited an electrical resistivity of about 60 Ω cm, suitable for infrared source element applications.