Limits to the Stability of the Amorphous Nature of Polymer-Derived HfSiCNO Compounds

• Published in: Journal of the American Ceramic Society Vol. 96; no. 7; pp. 2117 - 2123
• Main Authors: Terauds, Kalvis, Raj, Rishi
• Format: Journal Article
• Language: English
• Published: Columbus Blackwell Publishing Ltd 01.07.2013; Wiley Subscription Services, Inc
• Subjects: Amorphous materials; Atoms & subatomic particles; Ceramics; Dielectrics; Electric charge; Hafnium; Hafnium oxide; Manufacturing; Nanomaterials; Nanostructure; Polymers; Silicon
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.12382

Substituting silicon by transition metals in polymer‐derived ceramics (PDCs) holds the potential for a new class of polymer‐derived ceramics for ultrahigh‐temperature structural applications. We present experiments that show that the solid solubility of HfO2 extends to Hf/Si ratio of <0.22. The materials are synthesized from (miscible) organic precursors. Similar to silicon‐based materials they remain amorphous after pyrolysis at 1000°C. Small‐angle X‐ray scattering and Raman spectra remain essentially unaltered. It is postulated that Hf, like Si, forms mixed‐bond tetrahedra with C, O, and N. The difference in the enthalpy of Hf‐based, and Si‐centered tetrahedra is calculated using single‐bond energies, reinforcing the feasibility of substituting Si with Hf or with Zr atoms. Such polymer‐based HfSiCNO compounds made directly from liquid organics, by a simple manufacturing process, may also be relevant to nanoscale dielectrics with low leakage electric charge in microelectronics applications.