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.

模式失配双光束热透镜技术是研究纳米流体在热工程中的热扩散率的灵敏工具。通过研究浓度依赖性的热扩散率，该工作报告了使用米粉作为天然碳前体的低温绿色碳化carbide（HfC）合成及其在传热纳米流体中的潜力。结构表征证实了HfC的形成，其难熔性通过热重分析中观察到的高热稳定性得以揭示。Tauc图分析显示直接带隙能量为2.92 eV。荧光研究表明蓝粉红色发射具有CIE坐标（0.271，0.263）。纳米流体中HfC临界浓度的存在决定了HfC在热传递或热阱应用中的适用性，表明浓度依赖于热对偶。因此，这项研究意义重大，因为它克服了使用有毒化学物质和昂贵的热传递设备来合成难熔HfC的现有方法的主要缺点。