Zr/Hf-containing metallocene-based ceramic precursors

Abstract

Polymer-derived-ceramic (PDC) route is an excellent strategy to tailor components at the molecular level, while existing synthetic methods face various problems such as complex preparation, multi-step reaction, and high conversion temperature, etc. Here, we propose an approach to prepare Zr-, Hf-, or Zr/Hf-containing metallocene-based ceramic precursors, which are constructed by the alkylation reaction between cyclopentadienyl ligand and methylene. Through the homogeneous and one-pot reaction occurs, we collect the target products. The reaction condition is mild, and the conversion temperature (1400 °C) is relatively low, and with a high ceramic yield (57.50–66.34%). The obtained metal-containing polymers are further converted to the orthorhombic phase (M7O8.79F9.71, M = Zr, Hf) after pyrolysis at 800 °C. Annealing at an intermediate temperature of 1400 °C in an argon atmosphere results in cubic crystalline ZrC or HfC nanoparticles embedded in a ceramic matrix. The free carbons are in-situ formed after high-temperature treatment, and higher disorder of carbons is observed with increasing temperature. This work provides a good strategy for the potential precursor of ultrahigh-temperature ceramics.