Structure and Properties of Boronated Graphite

Abstract

Boronated natural graphite compacts were prepared at a temperature of 1750°C under pressures between 0.1 and 0.5 GPa with a nominal B4C content of 2 wt.% and at 2200°C under a pressure of 19.8 MPa with nominal B4C contents of 1, 2.5 and 50 wt.%. Their interlayer spacing d002 and lattice constant a0 were determined. The measurements of the electrical resistivity, magnetoresistance and Hall coefficient for the compacts were carried out mainly at liquid nitrogen temperature. With the increased substitution of boron atoms, the interlayer spacing d002 decreases from the values of the reference natural graphite compacts, showing a trend of the lattice constant a0 to increase slightly. At liquid nitrogen temperature, all of the boronated compacts show the positive Hall coefficient decreasing with the increase in substituted and ionized boron atoms. Below liquid nitrogen temperature, the boronated compacts except the slightly boronated ones exhibit the negative magnetoresistance and almost temperature independent resistivity.