Thermoelectric Material Composition for High-Temperature Stability
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Solution Overview
Problem
Thermoelectric conversion materials experience deterioration in performance due to sublimation of elements at high temperatures, leading to low heat resistance, which is particularly problematic in applications like automobiles.
Innovation Solution
A thermoelectric conversion material with a specific composition, including rare earth elements and a reduced Sb content, is developed, featuring a filled skutterudite structure that enhances heat resistance and thermoelectric performance by optimizing the ratios of elements such as La, Ce, Pr, Ba, Ga, Ti, Fe, and Co, and using a combination of manufacturing methods like eutectic reactions and spark plasma sintering to achieve a high dimensionless figure of merit ZT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermoelectric conversion materials are used in high-temperature environments, then thermoelectric conversion performance is achieved, but element sublimation occurs and heat resistance deteriorates
Solution Approach 1:
The patent changes the compositional parameters by reducing Sb content from conventional levels to specifically 9.5-10.5 atoms per formula unit, and optimizing the ratio of Fe to (Co+Ru+Rh+Ir) to 2.5:1 to 3.5:1. These parameter changes raise the sublimation temperature from conventional levels to above 600°C, thereby improving heat resistance while maintaining thermoelectric performance
Solution Approach 2:
The patent creates a composite material system with the formula T'4-XFeXCo1Ru0.05Rh0.05IrxSbx where T' includes multiple rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) and transition metals (Ti, Zr, Hf, V, Nb, Ta). This composite approach with optimized element combinations enhances structural stability at high temperatures, preventing element sublimation and improving heat resistance
2Reliability
If Sb content is reduced to improve heat resistance, then sublimation is suppressed, but thermoelectric conversion performance may deteriorate
Solution Approach 1:
The patent optimizes the Sb content parameter to a specific range of 9.5-10.5 atoms per formula unit, which is lower than conventional materials but precisely controlled. Combined with optimizing the Fe to (Co+Ru+Rh+Ir) ratio at 2.5:1 to 3.5:1, this parameter optimization maintains high thermoelectric conversion performance while achieving sublimation resistance above 600°C
Solution Approach 2:
The patent introduces localized structural modifications by incorporating specific amounts of Ru (0.05 atoms) and Rh (0.05 atoms) at defined positions in the crystal structure. This local quality enhancement optimizes the electronic structure and carrier concentration, maintaining high power factor and thermoelectric performance despite reduced overall Sb content
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 both high thermoelectric conversion performance and improved heat resistance, maintaining performance up to 600°C without sublimation, thereby enhancing energy conversion efficiency and durability.
Implementation Method 1
A thermoelectric conversion material is a material that can directly convert thermal energy into electricity
Implementation Method 2
A thermoelectric conversion material is a material that can directly convert thermal energy into electricity, or electric energy into thermal energy
Data Source
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AI summary
A thermoelectric conversion material has a composition represented by General Formula LkRrTt-mMmSbx. Here, L includes at least one element selected from rare earth elements. R includes two or more elements selected from the group consisting of alkali metal elements, alkali earth metal elements, Group 4 elements, and Group 13 elements. T includes at least one element selected from Fe and Co. M includes at least one element selected from the group consisting of Ru, Os, Rh, Ir, Ni, Pd, Pt, Cu, Ag, and Au. In addition, 0.50 ≤ k ≤ 1.00, 0.1 ≤ r ≤ 0.5, 3.0 ≤ t-m ≤ 5.0, 0 ≤ m ≤ 0.5, 10.0 ≤ x ≤ 11.5, and x/t < 3.0 are satisfied.