Magnetocaloric effect in low cost MnNiSi-based alloys with Fe and Sn doping

• Main Author: Gan, Joey Jie Yi
• Other Authors: Raju V. Ramanujan
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/73757
• Institution: Nanyang Technological University

Magnetocaloric materials has been of great interest in recent years due to its potential of replacing the current refrigeration technology – vapor compression system, which is causing environmental concern due to its greenhouse gas emissions. The study of magneto-caloric effects is still relatively new, with its focus mainly on rare-earth metal such Gd and La which are of high costs. For commercialization to be made possible, many researches are being done on lower cost and rare-earth free alternatives for magnetocaloric materials. This report shares the result of the experiments conducted on the Mn1-xNiSi1-yFexSny system, where x is fixed at 0.55, with varying y of 0.12, 0.14, 0.16 and 0.18. Crystallographic and magnetic changes, together with their Transition Temperature (Tt ) and Curie Temperature (Tc ) were recorded. The alloy samples were characterized using X-Ray Diffraction (XRD), Physical Property Measurement System (PPMS) and Differential Scanning Calorimeter (DSC). Virgin effect during the initial heating and cooling cycles were observed, which is also known as training effect. The highest entropy change ΔSM achieved in the experiments was 8.64 Jkg-1K-1 (ΔH = 5T) for y = 0.14, while RCP value obtained was 43.2 J/kg. The Tc for y = 0.14 alloy was found to be 335K (heating) and 315K (cooling), while Tt was at 358K (heating) and 310K (cooling).