Nano-volcanic Eruption of Silver.

Shih-kang Lin,Chulmin Oh,Hao Zhang,Shih-guei Lin,Emi Yokoi,Yu-chen Liu,Shijo Nagao,Katsuaki Suganuma

doi:10.1038/srep34769

Abstract

Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties. Ag thin films are extensively used in modern electronics primarily because of their oxidation-resistance. Here we report a novel phenomenon of Ag nano-volcanic eruption that is caused by interactions between Ag and oxygen (O). It involves grain boundary liquation, the ejection of transient Ag-O fluids through grain boundaries, and the decomposition of Ag-O fluids into O2 gas and suspended Ag and Ag2O clusters. Subsequent coating with re-deposited Ag-O and the de-alloying of O yield a conformal amorphous Ag coating. Patterned Ag hillock arrays and direct Ag-to-Ag bonding can be formed by the homogenous crystallization of amorphous coatings. The Ag “nano-volcanic eruption” mechanism is elaborated, shedding light on a new mechanism of hillock formation and new applications of amorphous Ag coatings.

Highlights

Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties
The mechanism of whisker formation has been extensively studied over the past few decades, primarily due to the serious concerns for whisker-induced failures in electronic, military, and aerospace devices
The “oxide-breaking” mechanism is generally accepted to be the mechanism of metallic whisker or hillock formation: most of the stressed atoms diffuse through grain boundaries, break through the oxide layer and accumulate locally at the free surface, forming whiskers or hillocks to release the stress[9]

Summary

Introduction

Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties. We report a novel phenomenon of Ag nano-volcanic eruption that is caused by interactions between Ag and oxygen (O). Ag is an important engineering material in the electronic, medical, and chemical industries and being a precious material for decorations, arts, and the storing of wealth. This wide range of applications of Ag is attributable to its unique noble and catalytic properties. The mechanisms of abundant Ag hillock formation and pressure-less direct Ag-to-Ag bonding are explained

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Results

Conclusion