Processing and Synthesis Mechanisms of MOF-Derived Nanopowders

Used sol–gel synthesis to prepare Zr-MOF, (Zr,Y)-MOF and Hf-MOF precursors, systematically varying synthesis, pyrolysis and carbothermal-conversion conditions to obtain high-purity ZrC, (Zr,Y)C and HfC nanopowders. Established process–phase–property relationships and investigated precursor conversion, solid-solution formation and doping, and oxygen impurity control. The resulting powders support the preparation of stable ceramic dispersions and ultrahigh-temperature ceramic composites.

Conducted controlled precursor synthesis and pyrolysis/carbonization experiments for the Zr, Zr–Y and Hf systems. Optimized metal-source/ligand ratios, metal-source molar ratios, solvent concentration, temperature and reaction time, as well as pyrolysis atmosphere, carbonization temperature and dwell time. Characterized and compared phase purity, morphology and particle-size distributions. Studied carbide formation in each metal system and the effects of Y incorporation on solid-solution formation, defects, impurities and particle evolution.

1) Led a national undergraduate innovation training project to completion and mentored a junior student through a provincial project; 2) received a national silver award in the China International College Students’ Innovation Competition; 3) published the HfC powder study (High-purity, uniform and spherical HfC nanoparticles derived from a novel amorphous Hf-MOF precursor for preparation of high-performance HfC ceramics). Results on (Zr,Y)C are being prepared for publication.