MgSiSn Thermoelectric Material with Void Silicon Layer
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Solution Overview
Problem
Current thermoelectric materials face challenges in achieving lower thermal conductivity and electrical resistivity simultaneously.
Innovation Solution
A thermoelectric material with an MgSiSn alloy as the main component, featuring a void structure and a silicon layer on its walls, along with MgO content, and regions with varying Sn and Si composition ratios, and particle mixing at boundaries, is developed. This material includes amorphous and microcrystalline silicon and uses polyvinyl alcohol for void formation during secondary sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If porous structure is introduced to reduce thermal conductivity, then thermal conductivity decreases, but electrical resistivity increases
Solution Approach 1:
The patent introduces a porous structure with voids into the MgSiSn alloy to reduce thermal conductivity. The voids scatter phonons and reduce heat transfer through the material, achieving lower thermal conductivity while maintaining electrical performance through careful control of void size, distribution, and content.
Solution Approach 2:
The patent creates regions with different compositions and structures within the thermoelectric material. Specifically, it forms Sn-rich and Si-rich regions with different particle sizes and compositions, allowing different areas to contribute differently to thermal and electrical properties, thereby resolving the contradiction between thermal conductivity and electrical resistivity.
2Temperature
If void content is increased to lower thermal conductivity, then thermal conductivity decreases, but material strength deteriorates
Solution Approach 1:
The patent optimizes the void content to be within a specific range (5-50%) to achieve the desired thermal conductivity reduction while maintaining adequate mechanical strength. The controlled porosity allows heat scattering without creating excessive structural weakness.
Solution Approach 2:
The patent creates a composite structure combining MgSiSn alloy with voids and silicon layers. This composite approach allows the voids to reduce thermal conductivity while the surrounding alloy matrix and silicon layers maintain structural integrity and mechanical strength.
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 material achieves low thermal conductivity and electrical resistivity, enhancing thermoelectric performance with a power factor and ZT value of 1 or greater, while maintaining material stability and reproducibility.
Implementation Method 1
a silicon layer that is formed on at least a wall surface of the void and that includes silicon as a main component
Implementation Method 2
a void formed in the parent phase
Implementation Method 3
a parent phase in which an MgSiSn alloy is a main component
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A thermoelectric material 1 includes a parent phase 10 in which an MgSiSn alloy is a main component, a void 12 formed in the parent phase 10, and a silicon layer that is formed on at least a wall surface of the void 12 and that includes silicon as a main component. The thermoelectric material 1 further includes MgO in an amount of 1.0 wt.% or more and 20.0 wt.% or less. The silicon layer includes amorphous Si, or amorphous Si and nanosized Si crystals, and the parent phase 10 includes a region in which the composition ratio of the Si of the chemical composition of the MgSiSn alloy is higher than in the other regions and a region in which the composition ratio of the Sn of the chemical composition of the MgSiSn alloy is higher than in the other regions. With these configurations, the thermoelectric material 1 realizes both lower thermal conductivity and lower electrical resistivity.