Document Type

Thesis

Comments

Bachelor of Science in Chemistry

Thesis advisor: David Carnevale, Ph.D.

Abstract

This project centered around the synthesis and modification of three materials in the Heusler alloy family CoxNiySn. These compounds consist of the two full Heuslers, Co2NiSn (10.7 nm) and Ni2CoSn (17.4), as well as the half-Heusler counterpart, CoNiSn (14.9 nm). This work also studies the growth of the nanoscale Heusler alloys to the bulk material through annealing at 600°C, which lead to increased crystallinity of Ni2CoSn but phase segregation of the Co2NiSn and CoNiSn. The initial nanoparticles were synthesized utilizing a CEM microwave with temperatures of 175/200°C. Samples were analyzed by X-Ray diffraction (XRD) for their crystallinity, which showed a hexagonal structure for all three alloys, while X-Ray fluorescence (XRF) was done to confirm elemental abundance. Magnetic properties were characterized by using a Physical Properties Measurement System (PPMS) where initial studies of the CoNiSn exhibited Hc and Ms values of 0.08 T and 6 emu*g-1, respectively. Shelling studies were performed on the core materials to observe the effects of different anisotropies on magnetic behavior with either a nickel shell (KNi< 0) or cobalt shell (KCo>0). Initial shelling studies exhibited a 25% increase in Hc with the nickel shell and a 75% decrease in Hc with the cobalt shell.

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