Low-temperature synthesis of ZrB2 nano-powders using a sorbitol modified sol–gel processing route

•Pure and uniform ZrB2 nano-powders were obtained at 1450 °C for 1 h using sorbitol as modifier.•Sorbitol acted as carbon source participating in carbothermal reduction reaction with char yield of 75%.•The influence of sorbitol on sol–gel process and synthesis mechanism were discussed.

High-purity zirconium diboride nano-powders were synthesized by carbothermal reduction reaction at a relatively low temperature from a novel sorbitol modified sol–gel method. Phase composition and morphology of the ZrB2 nano-powders were characterized by X-ray diffraction and transmission electron microscopy, respectively. The effect of sorbitol on sol–gel process and the formation mechanism of ZrB2 powders were investigated by fourier transform infrared spectroscopy and thermo gravimetric/differential thermal analysis. Sorbitol, used as bridging and chelating ligand, led to the formation of chelate complex through its polyhydroxy opening reaction with H3BO3, and then induced the condensation of zirconia forming Zr–O–C–B network, which promoted the carbothermal reduction reaction to complete at 1450 °C for 1 h. The synthesized powders exhibited near-spherical morphology with a small average crystalline size of about 100 nm. With respect to the conventional solid state method, the sorbitol modified sol–gel method route guaranteed a faster, easier and energy-saving process for obtaining single-phase nano-powders.

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