Yield properties, phase transition, and equation of state of aluminum nitride (AlN) under shock compression up to 150 GPa

Inclined-mirror Hugoniot measurements were performed on pure AlN polycrysta ls in the pressure range up to 150 GPa to study the yield properties, phase transition, and equation of state. The Hugoniot-elastic limit (HEL) stress was approximately 9.4 GPa. Above the HEL, the Hugoniot data converged to a static compression curve despite the high thermal conductivity, which indi cated that the thermal property is not an important factor in determining t he shock yield property. The phase transformation from wurtzite-type (B4) t o rock salt-type (B1) structure took place at approximately 19.4 GPa, and w as completed by about 75 GPa. The corrected transition pressure at 298 K wa s 19.2 GPa. Shock velocity (U-s) versus particle velocity (U-p) relation of the final phase was given by U-s = 3.27 + 1.81U(p) km/s. The Birch-Murnagh an fitting curve of the calculated isothermal compression curve of the B1-t ype phase roughly coincided with the recent static x-ray diffraction data u p to over 100 GPa. The Gruneisen parameter, bulk moduli (K-0), and the pres sure derivative (K-0') at zero pressure of the B1-type phase were estimated to be 1.51 +/- 0.03, 304 +/- 4 GPa, and 3.9 +/- 0.2 (K-0" = -0.02), respec tively. (C) 1999 American Institute of Physics. [S0021-8979(99)00724-0].