On the Coalescence of Nanoparticulate Gold Sinter Ink

Abstract

We examine the mechanism by which thiol-protected gold nanoparticle inks can sinter at surprisingly low temperatures. At room temperature the sample is comprised of randomly close-packed gold nanoparticles of about 2.3 nm diameter with a ligand shell of about 0.2 nm effective thickness. As the particles are heated through 80 °C they begin to coarsen, reaching about 10 nm diameter at 180 °C. Upon further heating, rapid sintering and grain growth occurs at a temperature that depends on environment and heating rate. Sintering in vacuum requires a higher temperature than in oxidizing environments. Mass spectrometry in the former case is consistent with volatile species such as C4H9, C2SH, and C2H4 being displaced, whereas XPS shows that the exposed surface of the Au is rich in C and S. However, when sintering is performed in the presence of even trace O2, it is the Au–S bond that is cleaved, and the sintering temperature is lowered by up to 50 °C. In this case mass spectrometry shows the generation of alkane and thiol fragments, some S2 and H2S, and oxidized sulfur-containing species, whereas XPS shows that C and S on the Au surface is much reduced.

On the Development of Optical Properties during Thermal Coarsening of Gold Nanoparticle Composites

“…The synthesized BT@AuNPs were 2-5 nm in diameter and as described in our previous work. 8,20,27 The dark brown color of the colloid and the lack of a plasmon peak in the visible region (Supporting Information, Figure S1) are consistent with AuNPs on the size threshold for the emergence of localized surface plasmon resonance (LSPR). 28 The OT@AuNPs were reasonably monodisperse at ~5 nm in diameter (Supporting Information, Figure S2), with a plasmon resonance peak at 518 nm (Supporting Information, Figure S1).…”

Influence of Bound versus Non-Bound Stabilizing Molecules on the Thermal Stability of Gold Nanoparticles

“…greater magnification reveals it to be coated with layers of AuNPs ( Figure S7) unlike crystals deposited from chloroform (Figure 6c). At 100 °C the film of AuNPs in the regions between the crystals ( Figure S8) shows the initial sintering stages of diffusion and neck formation between adjacent particles, 22,34 which by 200 °C have coarsened into much larger particles of ~20 nm diameter (Figure 7d demonstrate that without an anchoring group, the stabilizing RuPc compound does not become homogeneously distributed between the AuNPs in the film but instead aggregates into distinct crystals, in contrast to films formed using [RuPc(4-py(CH2)3SAc)(4-py t Bu)] as stabilizer. 24 This behavior leaves the AuNPs vulnerable to sintering at lower temperatures than when the stabilizer is anchored directly to the particles.…”

A new approach for additive-free room temperature sintering of conductive patterns using polymer-stabilized Sn nanoparticles

“…Until now, NPs of noble metals such as Au 16,17 and Ag [11][12][13]18,19 have been widely investigated for this purpose because of their high stability and conductivity. However, the high cost and sintering temperature of noble metal NPs limit their practical applications.…”