Copper-Silver Core-Shell Nanowires for Oxidation-Stable Conductivity
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Solution Overview
Problem
Copper nanowires suffer from rapid oxidation when exposed to air, leading to decreased electrical conductivity, and existing core-shell structures face challenges in maintaining uniformity and preventing copper oxide formation during secondary processing.
Innovation Solution
A copper nanowire with a core-shell structure where the core is coated with a thin, uniform layer of silver, with a specific thickness and diameter ratio, and a silver nitrate-ammonia complex solution is used to form a dense and uniform silver coating, ensuring the copper core is protected from oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shell is coated on copper nanowire to prevent oxidation, then oxidation resistance is improved, but the shell may be non-uniform or expose core metal during secondary processing
Solution Approach 1:
The patent applies preliminary action by forming a uniform shell structure on the copper nanowire core before secondary processing. The shell is carefully controlled to have specific thickness (5-40 nm) and uniformity to prevent oxidation during subsequent cutting and assembly operations. This preliminary protective structure ensures that the core metal remains protected throughout the manufacturing process.
Solution Approach 2:
The patent employs a thin film shell structure with controlled thickness of 5-40 nm that conforms to the core nanowire geometry. This thin flexible shell provides effective oxidation protection while maintaining the overall nanowire flexibility and preventing shell fracture during secondary processing operations such as cutting and bending.
2Reliability
If shell thickness is increased to improve oxidation protection, then oxidation stability is improved, but electrical conductivity and transparency deteriorate
Solution Approach 1:
The patent optimizes the shell thickness parameter to a specific range of 5-40 nm, which provides sufficient oxidation protection while minimizing the impact on electrical conductivity and transparency. This parameter optimization balances the protective function with the electrical performance requirements of the nanowire composite.
Solution Approach 2:
The shell provides localized oxidation protection at the nanowire surface where it is most needed, while the bulk of the nanowire maintains its high electrical conductivity. The shell thickness is carefully controlled to provide protection only where required without significantly affecting the overall electrical properties of the conductive composite.
3Reliability
If shell thickness is increased to prevent copper exposure, then oxidation prevention is improved, but structural stability during secondary processing deteriorates
Solution Approach 1:
The thin shell structure with thickness of 5-40 nm maintains flexibility and conformability to the core nanowire, preventing shell fracture during cutting and assembly operations. The shell is thin enough to flex with the core but thick enough to provide continuous oxidation protection.
Solution Approach 2:
The core-shell composite structure combines the high electrical conductivity of copper core with the oxidation resistance of the shell material. This composite structure provides both mechanical stability during processing and chemical stability against oxidation, leveraging the complementary properties of the two materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The nanowire exhibits excellent oxidation stability with a high oxidation initiation temperature and maintains electrical conductivity even after secondary processing, as the silver coating effectively suppresses copper oxidation and ensures structural stability.
Implementation Method 1
a shell containing silver on the core... which is uniformly and thinly formed on the core and has significantly improved durability
Implementation Method 2
effectively prevent oxidation of a core metal by a shell
Implementation Method 3
a silver nitrate-ammonia complex solution is used to form a dense and uniform silver coating
Data Source
AI summary
The present invention relates to a metal nanowire having a core-shell structure, the metal nanowire being conductive and transparent while having excellent oxidation stability, and being capable of maintaining excellent oxidation stability even after a secondary process using the metal nanowire of the present invention. Specifically, the metal nanowire having a core-shell structure, according to the present invention, comprises a core containing copper, and a shell containing silver on the core, wherein the ratio (D/L) of the diameter (D) of the core to the thickness (L) of the shell is 10-60, the thickness of the shell is 5-40 nm, and the peak intensity (I1) of Ag 3d5/2 of silver and the peak intensity (I2) of Cu 2p3/2 of copper in the X-ray photoelectron spectrum satisfy the following Equation 1.I2/I1≤0.2(Equation 1)