ELECTRON AND PHOTON-ASSISTED IN-FLAME CRYSTALLIZATION OF METASTABLE BN FORMS

In our previous articles, the crystallization of E-BN, (a high pressur e shock wave BN form) from a hydrogen-oxygen flame containing vapours of BH3HN3 was described. In this work we apply additional flame excit ation using a UV photon beam and/or field emitted electrons. The sourc e of the electrons was a corona discharge and of the photons was a UV impulse laser with a power of 5 x 10(4) W. The crystallized materials were identified by transmission electron microscopy (TEM) and X-ray di ffraction (XRD). Under the photon and electron activated flames we obt ained the high pressure forms of boron nitride (BN), w-BN and E-BN. Th e w-BN form did not crystallize from the flame without activation. The crystallization results were compared with changes in the flame emiss ion spectra caused by the photon beam and/or the electrons.