# Optimum pyrolysis conditions to prepare the most crystalline boron carbide powder from boric acid–mannitol complex ester

## TL;DR

The study finds the best conditions to produce crystalline boron carbide powder from a boric acid-mannitol complex ester through pyrolysis.

## Contribution

The novel contribution is identifying optimal pyrolysis conditions (1400 °C for 4 h) to maximize crystallinity of boron carbide powder.

## Key findings

- Optimum pyrolysis conditions are 1400 °C for 4 h, yielding the most crystalline B4C particles.
- B4C particles have a mean size of 20 μm and a specific surface area of 13.5 m² g⁻¹.
- Pore sizes range from 2 to 36 nm with a mean of 14 nm.

## Abstract

A weak acidic complex ester (CE) in solid form was prepared by a condensation reaction between very weak boric acid (BA: H3BO3) and (D)-mannitol (MA: C6H14O6) by the molar ratio of BA/MA = 2. A boron carbide (B4C) precursor was obtained from heating of the CE at 400 °C for 4 h. The precursor was pyrolyzed under argon flow in the interval of 1300–1550 °C for 4 h and at 1400 °C for 1–4 h, respectively. The materials were examined using several techniques such as X-ray diffraction analysis, thermal analysis, scanning electron microscopy, particle size distribution, and nitrogen adsorption/desorption. The optimum pyrolysis temperature and duration were 1400 °C and 4 h, respectively. The most crystalline B4C particles were distributed between 1 and 100 μm with a mean particle size of 20 μm. The specific surface area and specific pore volume were 13.5 m2 g−1 and 0.09 cm3 g−1, respectively. The size of the pores was between 2 and 36 nm with a mean size of 14 nm.