Thermoelectric properties of p-type Sb2Te3-based nanocomposites

Waste heat is inevitably produced by all processes doing work. Home heating, automotive exhaust and industrial processes are some of the examples of processes that generate an enormous amount of waste heat. Hence, it is of great environmental and economic benefit to convert this waste heat into renewable energy source. One such technology that can recover waste heat is thermoelectricity. This report focuses on investigating the use of Black Phosphorus doped Antimony Telluride Sb2Te3-BP (p-type) as an environmental friendly and cost effective thermoelectric generator for waste heat recovery. In this study, different compositional ratios of BP-doped Sb2Te3 were synthesized and analysed to achieve the best thermoelectric performance. Black Phosphorus doped Antimony Telluride samples were prepared by High Energy Ball Milling (HBM), and the resulting powders were sintered into pellets using Spark Plasma Sintering (SPS). They were then cut into disc-shaped and polished for morphology characterization using X-ray Diffraction (XRD), Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Field-Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-rays (EDS). The performance characterization was studied using Physical Properties Measurement System (PPMS). Further study on the impact of BP incorporation to Sb2Te3-based alloy, namely Bi0.5Sb1.5Te3, was also covered. After measurements, it was found that the addition of BP into Sb2Te3-based alloys relatively generated a positive impact. A high performing Sb2Te3-matrix sample could be achieved with 10wt% BP addition, reaching a ZTmax of 0.65. This composite shows an improvement of performance by 40% compared to the BP-free Sb2Te3 sample. The incorporation of 5wt% BP, however, deteriorated the ZTmax of the sample at the same temperature. Possible reasons for such phenomenon would be discussed in the report. This study has also proven the possible approach of preparing Black Phosphorus nanopowders from Red Phosphorus through affordable and simple High-energy Ball Milling method. Lastly, recommendations were also proposed by this study to offer viable solutions for future optimization.Bachelor of Engineering (Materials Engineering