Sol–gel synthesis and characterization of SiO2–Tac nanocomposites with controlled volume fraction

• Published in: Journal of sol-gel science and technology 2014-10, Vol.72 (1), p.189-196
• Main Authors: Chatterjee, Trisita, Bhattacharjee, Kaustav, Chaudhuri, Mahua Ghosh, Mitra, M. K., Das, G. C.
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Electron microscopes; Exact sciences and technology; Field emission microscopy; General and physical chemistry; Glass; Inorganic Chemistry; Materials Science; Microscopy; Nanocomposites; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper; Partial pressure; Scanning electron microscopy; Silicon dioxide; Sol-gel processes; Synthesis; Tantalum; Tantalum carbide; Tantalum oxides; Tetraethyl orthosilicate; Transmission electron microscopy; X ray powder diffraction; X-ray diffraction
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-014-3435-0

Nanocrystalline tantalum carbide (TaC) particles of average size ~15 nm dispersed in silica matrix, have been synthesized by the carbothermal reduction of Ta 2 O 5 over a range of temperature 1,100–1,360 °C in Ar atmosphere. Investigation of the stability diagram of carbon saturated Ta–O–N system suggests that the TaC phase can be successfully synthesized within the SiO 2 matrix when the partial pressure of O 2 and N 2 are restricted to approximately lower than 1.25 and 0.0001 atm. respectively. Two different synthesis routes are investigated in the present study which differ fundamentally in the order of addition of the precursors, tetraethyl orthosilicate (TEOS) and tantalum isopropoxide (Ta-iso). Rietveld refinement analyses of the powder X-ray diffraction data are carried out for the quantitative estimation of the two phases in the samples. The yield of TaC increases from 18 to 52 % when both TEOS and Ta-iso are added simultaneously to the water compared to the process where TEOS is added first to the water followed by the delayed addition of Ta-iso. Samples are further characterized by field emission scanning electron microscopy and high resolution transmission electron microscopy.