Condensation of sp³-bonded boron nitride through a highly nonequilibrium fluid state

Exceptionally highly crystalline sp³-bonded boron nitride showing Kikuchi lines in transmission electron diffraction was formed by pulsed laser vaporization deposition assisted with synchronously pulsated reactive plasma. Transmission electron microscopic observations indicated that a fluid-state precursor material was generated by the high-power nanosecond laser at 193 nm. Other sp²- and sp³-hybridized nanostructures with exceptionally wide variations in density, reflecting the original large density fluctuations, suggested that the precursor material was formed in the vicinity of the thermodynamic critical point (CP). These results as well as the exceptionally fast growth rates indicated a new mode of crystal growth, namely, the direct condensation of nonequilibrium-phase crystals from the fluid state near the CP.