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On the self-damping nature of densification in photonic sintering of nanoparticles.

MacNeill W, Choi CH, Chang CH, Malhotra R - Sci Rep (2015)

Bottom Line: It is shown that smaller nanoparticles result in faster densification, with lower temperatures during sintering, as compared to larger nanoparticles.It is shown that photonic sintering is an inherently self-damping process, i.e., the progress of densification reduces the magnitude of subsequent photonic heating even before full density is reached.By accounting for this phenomenon, the developed coupled model better captures the experimentally observed sintering temperature and densification as compared to conventional photonic sintering models.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Oregon State University, Corvallis, Oregon, USA.

ABSTRACT
Sintering of nanoparticle inks over large area-substrates is a key enabler for scalable fabrication of patterned and continuous films, with multiple emerging applications. The high speed and ambient condition operation of photonic sintering has elicited significant interest for this purpose. In this work, we experimentally characterize the temperature evolution and densification in photonic sintering of silver nanoparticle inks, as a function of nanoparticle size. It is shown that smaller nanoparticles result in faster densification, with lower temperatures during sintering, as compared to larger nanoparticles. Further, high densification can be achieved even without nanoparticle melting. Electromagnetic Finite Element Analysis of photonic heating is coupled to an analytical sintering model, to examine the role of interparticle neck growth in photonic sintering. It is shown that photonic sintering is an inherently self-damping process, i.e., the progress of densification reduces the magnitude of subsequent photonic heating even before full density is reached. By accounting for this phenomenon, the developed coupled model better captures the experimentally observed sintering temperature and densification as compared to conventional photonic sintering models. Further, this model is used to uncover the reason behind the experimentally observed increase in densification with increasing weight ratio of smaller to larger nanoparticles.

No MeSH data available.


Predicted temperature evolution for unmixed inks (a) coupled model (b) constant heating model.
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f7: Predicted temperature evolution for unmixed inks (a) coupled model (b) constant heating model.

Mentions: At the same time, a new observation is that reduces by almost an order of magnitude as x/b increases. Since the progress of densification (with greater x/b) causes a reduction in subsequent photonic heating, therefore photonic sintering is a self-damping process. Figures 7, 8, 9 show model predictions corresponding to the total optical power incident on the nanoparticles during experiments. Figure 7 shows that the coupled model and the constant heating model capture the greater rise in temperature for larger nanoparticles, which is also seen in experiments. However, the experimentally observed trend (Fig. 4a) of a spike in temperature followed by stabilization to a steady state temperature as well as the peak temperature magnitudes, are better captured by the coupled model. For example, the constant heating model predicts that the 40 nm nanoparticles reach melting point, which is not seen experimentally and is also not predicted by the coupled model.


On the self-damping nature of densification in photonic sintering of nanoparticles.

MacNeill W, Choi CH, Chang CH, Malhotra R - Sci Rep (2015)

Predicted temperature evolution for unmixed inks (a) coupled model (b) constant heating model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595846&req=5

f7: Predicted temperature evolution for unmixed inks (a) coupled model (b) constant heating model.
Mentions: At the same time, a new observation is that reduces by almost an order of magnitude as x/b increases. Since the progress of densification (with greater x/b) causes a reduction in subsequent photonic heating, therefore photonic sintering is a self-damping process. Figures 7, 8, 9 show model predictions corresponding to the total optical power incident on the nanoparticles during experiments. Figure 7 shows that the coupled model and the constant heating model capture the greater rise in temperature for larger nanoparticles, which is also seen in experiments. However, the experimentally observed trend (Fig. 4a) of a spike in temperature followed by stabilization to a steady state temperature as well as the peak temperature magnitudes, are better captured by the coupled model. For example, the constant heating model predicts that the 40 nm nanoparticles reach melting point, which is not seen experimentally and is also not predicted by the coupled model.

Bottom Line: It is shown that smaller nanoparticles result in faster densification, with lower temperatures during sintering, as compared to larger nanoparticles.It is shown that photonic sintering is an inherently self-damping process, i.e., the progress of densification reduces the magnitude of subsequent photonic heating even before full density is reached.By accounting for this phenomenon, the developed coupled model better captures the experimentally observed sintering temperature and densification as compared to conventional photonic sintering models.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Oregon State University, Corvallis, Oregon, USA.

ABSTRACT
Sintering of nanoparticle inks over large area-substrates is a key enabler for scalable fabrication of patterned and continuous films, with multiple emerging applications. The high speed and ambient condition operation of photonic sintering has elicited significant interest for this purpose. In this work, we experimentally characterize the temperature evolution and densification in photonic sintering of silver nanoparticle inks, as a function of nanoparticle size. It is shown that smaller nanoparticles result in faster densification, with lower temperatures during sintering, as compared to larger nanoparticles. Further, high densification can be achieved even without nanoparticle melting. Electromagnetic Finite Element Analysis of photonic heating is coupled to an analytical sintering model, to examine the role of interparticle neck growth in photonic sintering. It is shown that photonic sintering is an inherently self-damping process, i.e., the progress of densification reduces the magnitude of subsequent photonic heating even before full density is reached. By accounting for this phenomenon, the developed coupled model better captures the experimentally observed sintering temperature and densification as compared to conventional photonic sintering models. Further, this model is used to uncover the reason behind the experimentally observed increase in densification with increasing weight ratio of smaller to larger nanoparticles.

No MeSH data available.