Synthesisand Electrical Properties of Layered-Ternary Nitrides Ti₂AN （A=Al, Ga）

The bulk polycrystalline Ti₂AlN,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 Ti₂GaN 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 Ti₂AlN and Ti₂GaN had the ideal stoichiometry and typical metallic conductivity.To be specific,as the temperature decreased from 300 to 5 K,the resistivity of Ti₂AlN and Ti₂GaN nitrides decreased and no superconductivity was observed at a temperature above 5 K.