Crystal growth and characterization of HPHT diamond from a phosphorus-carbon system

摘要

Crystallization of diamond in the phosphorus-graphite system has been studied at 7 GPa and 1750 deg C in a series of experiments with duration from 5 to 20 h. Spontaneous diamonds crystallized through both film growth (FG) and temperature gradient growth (TGG) processes as well as diamond layers grown on seed crystals were obtained. Morphology of the crystallized diamonds was studied by scanning electron microscopy and goniometry. For TGG diamonds faces of tetrahexahedron and trapezohedron indexed as {310} adn {911}, respectively, which are the new growth forms of synthetic diamond, were established. By FTIR measurement it was shown that bluish coloration charcteristic of crystallized diamonds arises from a continuum of absorption, which is similar to the phosphorus photo-ionization continuum seen in P-doped CVD diamond films.