MgAgAs Half-Heusler Thermoelectric Material Composition Control
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Solution Overview
Problem
Thermoelectric conversion materials with MgAgAs type crystal structures face challenges in maintaining uniformity of Ti molar concentrations, leading to variations in characteristics when used in modules, which affects their performance and efficiency.
Innovation Solution
A thermoelectric conversion material with a polycrystalline structure represented by the composition (AaTib)cDdXe, where A includes Zr and Hf, D includes Ni, Co, or Fe, and X includes Sn and Sb, with specific atomic ratios to stabilize the MgAgAs type crystal structure and incorporate regions of different Ti concentrations, ensuring improved ZT value and reduced variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a half-Heusler compound with MgAgAs type crystal structure is used to improve thermoelectric performance at high temperature, then the ZT value can be enhanced, but maintaining uniform Ti molar concentration becomes difficult leading to characteristic variations in modules
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Ti molar concentration within a specific range (0.3 ≤ b ≤ 0.8 in the composition formula (AaTib)cDdXe) and maintaining atomic ratios within defined ranges (0.2 ≤ a ≤ 0.7, 0.3 ≤ b ≤ 0.8, a+b=1). This systematic parameter optimization resolves the contradiction by establishing clear compositional boundaries that ensure both high ZT value and uniformity across modules, eliminating characteristic variations while maintaining enhanced thermoelectric performance.
2Reliability
If PbTe alloy is used in conventional thermoelectric conversion materials, then good thermoelectric performance is achieved, but harmful lead substances are present
Solution Approach 1:
The patent extracts and eliminates the harmful Pb (lead) element from the thermoelectric material composition entirely. By adopting a half-Heusler compound with MgAgAs type crystal structure and composition formula (AaTib)cDdXe where A includes Zr and Hf, D includes Ni, Co, or Fe, and X includes Sn and Sb, the invention removes toxic substances while preserving and enhancing thermoelectric conversion efficiency through optimized non-toxic element combinations.
Solution Approach 2:
The patent employs composite material strategy by creating a half-Heusler compound comprising multiple elements (A, Ti, D, X) in specific ratios. This composite structure with formula (AaTib)cDdXe combines Zr/Hf, Ni/Co/Fe, and Sn/Sb elements to achieve superior thermoelectric performance that replaces PbTe alloy, eliminating lead toxicity while maintaining or improving ZT value through synergistic element interactions.
3Reliability
If the composition formula (AaTib)cDdXe is used with specific atomic ratios, then uniformity and high ZT value are achieved, but manufacturing complexity increases
Solution Approach 1:
The patent manages composition control complexity through systematic parameter definition. By establishing clear atomic ratio ranges (0.2 ≤ a ≤ 0.7, 0.3 ≤ b ≤ 0.8, a+b=1, 0.93 ≤ c ≤ 1.08, 0.93 ≤ e ≤ 1.08) and specifying element groups (A: Zr/Hf, D: Ni/Co/Fe, X: Sn/Sb), the invention transforms complex multi-element composition control into manageable parameter specifications. This structured approach ensures characteristic uniformity and high ZT value while making manufacturing process control feasible through defined compositional boundaries.
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 solution results in a thermoelectric conversion material with a high ZT value and reduced variations in characteristics, enhancing the performance and stability of thermoelectric conversion modules, while also allowing for high-yield manufacturing.
Implementation Method 1
there has been an increasing interest a thermoelectric generation device providing a power generation system using unused waste heat energy and using the Seebeck effect
Implementation Method 2
there has been an increasing interest in a thermoelectric cooling element using the Peltier effect as a CFC-free cooling device
Data Source
AI summary
According to an embodiment, a thermoelectric conversion material is made of a polycrystalline material which is represented by a composition formula (1) shown below and has a MgAgAs type crystal structure. The polycrystalline material includes a MgAgAs type crystal grain having regions of different Ti concentrations.(AaTib)cDdXe Composition formula (1)wherein 0.2≦a≦0.7, 0.3≦b≦0.8, a+b=1, 0.93≦c≦1.08, and 0.93≦e≦1.08 hold when d=1; A is at least one element selected from the group consisting of Zr and Hf, D is at least one element selected from the group consisting of Ni, Co, and Fe, and X is at least one element selected from the group consisting of Sn and Sb.