Thermal dewetting with a chemically heterogeneous nano-template for self-assembled L1₀ FePt nanoparticle arrays

Journal Article · Tue Jan 26 04:00:00 EST 2016 · Nanoscale

DOI:https://doi.org/10.1039/c5nr08339g· OSTI ID:1480712

Wang, Liang-Wei ^[1]; Cheng, Chung-Fu ^[1]; Liao, Jung-Wei ^[1]; Wang, Chiu-Yen ^[2]; Wang, Ding-Shuo ^[1]; Huang, Kuo-Feng ^[1]; Lin, Tzu-Ying ^[1]; Ho, Rong-Ming ^[3]; Chen, Lih-Juann ^[1]; Lai, Chih-Huang ^[1]

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1. National Tsing Hua University, Hsinchu (Taiwan). Department of Materials Science and Engineering
2. National Taiwan University of Science and Technology, Taipei (Taiwan). Department of Materials Science and Engineering
3. National Tsing Hua University, Hsinchu (Taiwan). Department of Chemical Engineering

In this paper, a design for the fabrication of metallic nanoparticles is presented by thermal dewetting with a chemically heterogeneous nano-template. For the template, we fabricate a nanostructured polystyrene-b-polydimethylsiloxane (PS-b-PDMS) film on a Si|SiO₂ substrate, followed by a thermal annealing and reactive ion etching (RIE) process. This gives a template composed of an ordered hexagonal array of SiOC hemispheres emerging in the polystyrene matrix. After the deposition of a FePt film on this template, we utilize the rapid thermal annealing (RTA) process, which provides in-plane stress, to achieve thermal dewetting and structural ordering of FePt simultaneously. Since the template is composed of different composition surfaces with periodically varied morphologies, it offers more tuning knobs to manipulate the nanostructures. We show that both the decrease in the area of the PS matrix and the increase in the strain energy relaxation transfer the dewetted pattern from the randomly distributed nanoparticles into a hexagonal periodic array of L1₀ FePt nanoparticles. Transmission electron microscopy with the in situ heating stage reveals the evolution of the dewetting process, and confirms that the positions of nanoparticles are aligned with those of the SiOC hemispheres. The nanoparticles formed by this template-dewetting show an average diameter and center-to-center distance of 19.30 ± 2.09 nm and 39.85 ± 4.80 nm, respectively. The hexagonal array of FePt nanoparticles reveals a large coercivity of 1.5 T, much larger than the nanoparticles fabricated by top-down approaches. Lastly, this approach offers an efficient pathway toward self-assembled nanostructures in a wide range of material systems.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1480712
• Journal Information: Nanoscale, Journal Name: Nanoscale Journal Issue: 7 Vol. 8; ISSN NANOHL; ISSN 2040-3364
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE