The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis, metallography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only four distinct compositions: IrSi, Ir/sub 3/Si/sub 4/, Ir/sub 3/Si/sub 5/, and IrSi approximately /sub 3/. The existence of Ir/sub 4/Si/sub 5/ could not be confirmed, even though the crystal structure has been previously reported. Differential thermal analysis (DTA) in conjunction with X-ray powder diffraction confirm polymorphism in IrSi approximately /sub 3/, determined to have orthorhombic and monoclinic unit cells in the high- and low-temperature forms. A eutectic composition alloy of 83+or-1 at.% silicon was observed between IrSi approximately /sub 3/ and silicon. Ir/sub 3/Si/sub 4/ exhibits distinct metallic behavior while IR/sub 3/Si/sub 5/ is semiconducting. Both IrSi and IrSi approximately /sub 3/ exhibit nearly temperature independent electrical resistivities on the order of 5-10*10/sup -6/ Omega -m. (23 References).
BT - Proceedings of the 27th Intersociety Energy Conversion Engineering Conference (IEEE Cat. No.92CH3164-1). C1 - San Diego, CA, USA. IEEE. ACS. AIAA. AIChE. ANS. ASME. SAE. 3-7 Aug. 1992. DA - 1992/// LA - eng N2 -The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis, metallography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only four distinct compositions: IrSi, Ir/sub 3/Si/sub 4/, Ir/sub 3/Si/sub 5/, and IrSi approximately /sub 3/. The existence of Ir/sub 4/Si/sub 5/ could not be confirmed, even though the crystal structure has been previously reported. Differential thermal analysis (DTA) in conjunction with X-ray powder diffraction confirm polymorphism in IrSi approximately /sub 3/, determined to have orthorhombic and monoclinic unit cells in the high- and low-temperature forms. A eutectic composition alloy of 83+or-1 at.% silicon was observed between IrSi approximately /sub 3/ and silicon. Ir/sub 3/Si/sub 4/ exhibits distinct metallic behavior while IR/sub 3/Si/sub 5/ is semiconducting. Both IrSi and IrSi approximately /sub 3/ exhibit nearly temperature independent electrical resistivities on the order of 5-10*10/sup -6/ Omega -m. (23 References).
PB - Soc. Automotive Eng. Warrendale, PA, USA. PY - 1992 SP - 3.493 EP - 3.497 EP - T2 - Proceedings of the 27th Intersociety Energy Conversion Engineering Conference (IEEE Cat. No.92CH3164-1). TI - Phase diagram and electrical behavior of silicon-rich iridium silicide compounds UR - http://cvining.com/system/files/articles/vining/Allevato-IECEC-1992.pdf VL - 3 ER -