The band gap and electrical resistivity of FeS2-pyrite at high pressures

The indirect energy gap and electrical resistivity of FeS2-pyrite have been measured at high pressures and 300 K using optical absorption spectroscopy and electrical conductivity measurements. Absorption spectra extend to similar to28 GPa, while resistivity is determined to similar to34 GPa. The band gap of FeS2 is indirect throughout this pressure range and decreases linearly with pressure at a rate of -1.13(9) x 10(-2) eV/GPa. If this linear trend continues, FeS2 is expected to metallize at a pressure of 80(+/-8) GPa. The logarithm of resistivity also linearly decreases with pressure to 14 GPa with a slope of -0.101(+/-0.001)/GPa. However, between 14 and 34 GPa, the logarithm of resistivity is nearly constant, with a slope of -0.011(+/-0.003)/GPa. The measured resistivity of pyrite may be generated predominantly by extrinsic effects. (C) 2002 Published by Elsevier Science Ltd.