A general route for the convenient synthesis of crystalline hexagonal boron nitride micromesh at mild temperature

In this study, hexagonal boron nitride (h-BN) micromeshes with high crystallinity and yield have been prepared by B2O3, Mg and NaN3 in a stainless steel autoclave at 450 degrees C, which have diameters of up to 100 mm, thickness of similar to 210 nm and pore size of 2.8 mu m on average. A near-band edge emission at 217 nm of these micromeshes has been observed through the photoluminescence (PL) spectra. Their formation mechanism was considered through an oriented aggregation process, in which the in-situ produced MgO microparticles served as template. As B2O3 was substituted by other boron sources (such as H3BO3, Na2B4O7, NH4HB4O7 or Mg(BO2)(2)center dot H2O), h-BN micromeshes with different pore sizes could also be produced; therefore, it is a general way for the convenient synthesis of crystalline h-BN micromeshes. The as-obtained product is promising as a catalyst support, in chemical filtration and in separations under severe operating conditions.