Electrical Conductivity Measurement of -Boron under High Temperature and High Pressure

Boron possesses very complex structures and various physical characteristics under high pressure, which always attracts much attention in the field of theory and experiment. In situ electrical conductivity measurement under variable pressure and temperature conditions is a very important research into exploring conductive property of substance. Electrical conductivity of -B was measured with metallic microcircuit fabricated on the diamond anvil cell (DAC), and the conductive physical mechanism of -boron at high pressure and high temperature was analyzed. When sample was not heated, electrical conductivity of boron was rising with increasing pressure to 28 GPa; furthermore, we found that it almost recovers original state upon decompression. When temperature is changed from room temperature to 423 K, electrical conductivity begins to rise with increasing temperature, and the change rate becomes gradually high and the change trend of electrical conductivity is similar to that under different pressures in the same temperature range. Subsequently, laser-heating was performed on -B with designed DAC, Al2O3 thin film was deposited on the diamond anvil and used as heat resistant and electrical insulating layer. Electrical conductivity was separately measured at 14.5 GPa and 18.6 GPa. The highest temperature reached is 2 224 K. -boron is confirmed semiconductor property based on electrical conductivity increasing with elevated temperature.