LAUSR

The mode mismatch dual-beam thermal lens technique is a sensitive tool for studying the nanofluids’ thermal diffusivity in thermal engineering. The work reports the low-temperature green synthesis of hafnium carbide (HfC) using rice flour as a natural carbon precursor and its potential in heat transfer nanofluids by studying the concentration-dependent thermal diffusivity. The structure characterisations confirm the formation of HfC, whose refractory nature is revealed through the high thermal stability observed in the thermogravimetric analysis. The Tauc plot analysis shows direct bandgap energy of 2.92 eV. The fluorescence study suggests bluish-pink emission with CIE coordinates (0.271, 0.263). The existence of the critical concentration of HfC in the nanofluid decides its suitability for heat transfer or heat trap applications indicating a concentration-dependent thermal duality. Thus, the study is significant as it overcomes the major drawbacks of the existing methods of the synthesis of refractory HfC, using toxic chemical and costly equipment for heat transfer applications.