Laser-Induced Reductive Sintering of Nickel Oxide Nanoparticles under Ambient Conditions
Allen, Frances I.
Park, Hee K.
Minor, Andrew M.
Grigoropoulos, Costas P.
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Abstract© 2015 American Chemical Society. This work is concerned with the kinetics of laser-induced reductive sintering of nonstoichiometric crystalline nickel oxide (NiO) nanoparticles (NPs) under ambient conditions. The mechanism of photophysical reductive sintering upon irradiation using a 514.5 nm continuous-wave (CW) laser on NiO NP thin films has been studied through modulating the laser power density and illumination time. Protons produced due to high-temperature decomposition of the solvent present in the NiO NP ink, oxygen vacancies in the NiO NPs, and electronic excitation in the NiO NPs by laser irradiation all affect the early stage of the reductive sintering process. Once NiO NPs are reduced by laser irradiation to Ni, they begin to coalesce, forming a conducting material. In situ optical and electrical measurements during the reductive sintering process take advantage of the distinct differences between the oxide and the metallic phases to monitor the transient evolution of the process. We observe four regimes: oxidation, reduction, sintering, and reoxidation. A characteristic time scale is assigned to each regime.
CitationPaeng D, Lee D, Yeo J, Yoo J-H, Allen FI, et al. (2015) Laser-Induced Reductive Sintering of Nickel Oxide Nanoparticles under Ambient Conditions. The Journal of Physical Chemistry C 119: 6363–6372. Available: http://dx.doi.org/10.1021/jp512776p.
SponsorsPartial support to the Laser Thermal Laboratory by the King Abdullah University of Science and Technology (KAUST) is acknowledged. Laser Prismatics LLC was supported by the SBIR Phase I Grant No. 1346088 from the U.S. National Science Foundation. D.L. was supported by Gachon University research fund of 2014(GCU-2014-0107). The TEM analysis was performed at the Molecular Foundry, which is supported by the Office of Science, Office of Basic Energy Sciences, Scientific User Facilities Division, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The authors would also like to thank Dr. Jaewon Jang for assistance with the experiments and helpful discussions.
PublisherAmerican Chemical Society (ACS)