New strategies for selectively synthesizing cubic boron nitride in hydrothermal solutions

Abstract

By developing new strategies, cubic boron nitride crystals (cBN) were selectively synthesized by a hydrothermal method using H 3 BO 3 , NH 3 $H 2 O and N 2 H 4 $H 2 O as the reactants. The experimental results indicated that both the relative content and crystalline perfection of cBN were improved by increasing the reaction temperature. Furthermore, we developed two new strategies, i.e., pressurizing the reaction solution (with nitrogen) and quickly cooling down thereafter. As a result, cBN content and its crystalline perfection were also obviously improved. In addition, NaCl and NaF were found to possess the induction effect of promoting cBN formation, and the effect of NaF is much stronger than that of NaCl. In conclusion, by optimizing the preparation parameters and applying these new strategies, nearly pure cBN with quite high crystallinity has been prepared from hydrothermal solutions.

Halides‐Assisted Low‐Temperature Synthesis of Hexagonal Boron Nitride Nanosheets

“…As reported by Xing et al, the hBNQDs could be synthesized via the normal hydrothermal reaction starting from H 3 BO 3 (boron source) and NH 3 ·H 2 O (nitrogen source) at 200 °C ( Scheme a), but it is not applicable for the growth of hBNNS. As is well known, the halides have the ability to etch BN, including hBN and cBN, and have been found to be effective in the selective synthesis of cBN crystals . Inspired by the hBNQDs synthesis and the halides effect, we proposed the HAHTA synthetic method for the synthesis of hBNNS (Scheme b).…”

“…As is well known, the halides have the ability to etch BN, including hBN and cBN, [47] and have been found to be effective in the selective synthesis of cBN crystals. [43] Inspired by the hBNQDs synthesis and the halides effect, we proposed the HAHTA synthetic method for the synthesis of hBNNS (Scheme 1b). With respect to the possible mechanism, the edges of the hBNQDs formed at the initial stage of HAHTA may be activated by the halides etching, which may reduce the energy barrier for the further growth of hBNNS, and the continuous hydrothermal assembly gave rise to the final evolution from 0D hBNQDs to 2D hBNNS.…”

“…Hydrothermal is a typical low‐temperature synthetic method that has many advantages in mass production, green synthesis, and high crystallinity . As reported in literatures, the hBN quantum dots (hBNQDs) or micro/nanocrystals could be obtained under normal hydrothermal conditions. The attained hBNQDs have the thickness 0.35–1.25 nm and the lateral size 2–10 nm .…”

Hydrothermal synthesis of cubic boron nitride microcrystals

“…These results show that compared to cBN, hBN was preferentially etched in fluorinecontaining environment and the improved etching selectivity would facilitate the synthesis of high-quality cBN films via the chemical vapor deposition route. In addition, we also reported that halide species had obvious induction effect of cBN synthesis with NaN 3 and NH 3 as nitrogen-sources in hydrothermal condition [22,23]. Furthermore, for enlarging the applicability of induction effect in different nitrogen-source system, in this paper, we investigated the synthesis of cBN with N(CH 3 ) 3 as nitrogen source in hydrothermal condition.…”

Influence of Biofield Treatment on Physical, Structural and Spectral Properties of Boron Nitride

“…The BN originally exists in several crystal structures such as wurtzite BN (w-BN), cubic BN (c-BN), rhombohedral BN (r-BN), hexagonal BN (h-BN), explosive BN (e-BN), and turbostratic BN (t-BN). The c-BN and w-BN are especially known for super-hardness, wide band gap and its oxidation resistance which makes them a promising material for fabrication of cutting tools, protective coatings, and optoelectronic devices [4,5].…”