RANDOM MAGNETISM OF SUPERHIGH SURFACE-AREA CARBON HAVING MINUTE GRAPHITIC STRUCTURES

The magnetic properties of micrographitic structure-oriented carbons with different surface areas were examined over the temperature range of 1.7 to 300 K. Superhigh surface area carbon of specific surface area = 3110 m(2) g(-1), whose surface atom ratio is 0.94, showed a remarkable magnetic hysteresis and chi-T relation with maximum below 4.2 K. The magnetic hysteresis depended on the measuring temperature; the residual magnetization was 0.016 emu G g(-1) at 1.7 K and 0.015 emu G g(-1) at 300 K. The ferromagnetic behavior was dependent on the measuring time, and thereby the maximum of the chi-T relation shifted to lower temperature with a longer measuring time. On the contrary, low surface area carbon of surface area = 570 m(2) g(-1) showed no ferromagnetism.