THERMAL-DIFFUSIVITY OF ISOTOPICALLY ENRICHED C-12 DIAMOND

Type-IIA diamond single crystals containing approximately 0.1%, 0.5%, and 1% C13 were synthesized and their thermal diffusivities were measured at room temperature by the thermal-wave-mirage technique. The measured value (18.5 cm2/s) of the 0.1% C13 crystal was 50% higher than the 1% C13 (natural isotope abundance). This is the highest room-temperature thermal diffusivity of any solid naturally occurring or previously synthesized. The laser damage threshold at 193 nm for the isotopically enriched crystal is more than an order of magnitude higher than that of natural diamond. © 1990 The American Physical Society.