Pressure effect on phase transition of α-[(CH3)2(C2H5)2N][Ni(dmit)2]2

The pressure effect on the phase transition of α-[(CH3)2(C2H5)2N][Ni(dmit)2]2 has been studied. This salt exhibits the drastic structural phase transition at 245 K that causes a resistance jump. For the pressure dependence at room temperature, the resistance decreased abruptly in the pressure range between 0.11 and 0.18 GPa. On the temperature dependence measurements under 0.17 and 0.28 GPa, the small anomalies were observed at 280 and 304 K, respectively, instead of the resistance jump at 245 K. The T–P phase diagram showed that the phase transition temperature increased from 245 K to room temperature by applying pressure at the rate of ca. 20 K/0.1 GPa.