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However, existing measurement techniques often rely on complex setups, advanced electronics, or parameter fitting, limiting their practicality for routine use. This study introduces a simplified temperature oscillation method for precise thermal diffusivity measurements that utilizes a cost-effective and reliable setup comprising a thermofoil heater and four thermocouples, requiring a small sample volume (\u223c1\u2009ml). This makes it particularly well-suited for nanofluids, which are increasingly applied in advanced thermal management, innovative lubricants, pollutant remediation, and high-performance cooling systems. Experimental validation with water demonstrated excellent agreement with previously reported thermal diffusivity values, underscoring the accuracy and reliability of the technique. When applied to a luminescent nanofluid composed of NaGdF4:Yb\/Er(18\/2%)@NaGdF4 upconverting nanoparticles dispersed in water, the thermal diffusivity was comparable to that of distilled water challenging earlier reports of anomalous enhancements in nanofluid thermal properties.<\/jats:p>","DOI":"10.1063\/5.0252044","type":"journal-article","created":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T13:03:16Z","timestamp":1739365396000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":3,"title":["Thermal diffusivity of nanofluids: A simplified temperature oscillation approach"],"prefix":"10.1063","volume":"37","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8115-9819","authenticated-orcid":false,"given":"Ramon S. 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