Abstract:
The bulk polycrystalline Ti
2AlN,an advanced layered ternary ceramics(M
n+1AX
n),was synthesized by spark plasma sintering(SPS) of Ti,Al and TiN powders with a molar ratio of 1∶1∶1;and the bulk polycrystalline Ti
2GaN was grown by sintering the compressed Ti and GaN powders with a molar ratio of 2∶1 in a sealed quartz glass-tube.The influence of the synthesis conditions on the microstructures and electrical properties,particularly low-temperature superconductivity,was investigated with X-ray diffraction,energy dispersive X-ray spectroscopy and scanning electron microscopy.The preliminary results show that the single-phased,layered Ti
2AlN and Ti
2GaN had the ideal stoichiometry and typical metallic conductivity.To be specific,as the temperature decreased from 300 to 5 K,the resistivity of Ti
2AlN and Ti
2GaN nitrides decreased and no superconductivity was observed at a temperature above 5 K.