Bi-M-Cu-O Thermoelectric Material Phonon Scattering
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Solution Overview
Problem
Current thermoelectric conversion materials face challenges in achieving high energy conversion efficiency due to limitations in Seebeck coefficient, electric conductivity, and thermal conductivity, which affect the ZT value.
Innovation Solution
Development of new thermoelectric conversion materials with the formula Bi1-xMxCu1-wOa-yQ1yTeb-zQ2z, where M is selected from certain elements and Q1, Q2 are S, Se, or Sb, produced through heating mixtures of Bi2O3, Bi, Cu, Te, and optional oxides, with sintering at temperatures between 400 to 570°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional thermoelectric conversion materials are used, then the structure is simple and manufacturing is easy, but the energy conversion efficiency is insufficient due to limited ZT value
Solution Approach 1:
The patent employs composite material strategy by creating complex multi-element compounds (Bi-M-Cu-O-Q) that combine multiple elements with complementary properties. The base Bi-Cu-O structure provides good electrical conductivity while M elements (Ba, Sr, Ca, Mg, etc.) and Q elements (S, Se, As, Sb) are incorporated to reduce thermal conductivity and enhance Seebeck coefficient, achieving high ZT values through synergistic effects of different elements
Solution Approach 2:
The patent applies local quality principle by introducing specific elements at controlled concentrations (0<x≤0.5, 0<y≤0.5, 0<z≤0.5) into specific positions within the crystal structure. The M element substitutes at Bi sites while Q elements occupy Te sites, creating localized regions with optimized electronic and thermal properties that collectively enhance overall thermoelectric performance
2Loss of energy
If the material composition is optimized for high Seebeck coefficient and electric conductivity, then energy conversion efficiency improves, but thermal conductivity increases which reduces ZT value
Solution Approach 1:
The patent uses M elements (Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Tl, As, Sb) as intermediary elements that mediate between the conflicting requirements of high electrical conductivity and low thermal conductivity. These intermediary elements scatter phonons (reducing thermal conductivity) while maintaining or enhancing charge carrier transport (preserving electrical conductivity), thereby decoupling the thermal and electrical transport properties
Solution Approach 2:
The patent introduces point defects and nanoscale structural features through element substitution that create phonon scattering centers analogous to porous structures. The M and Q elements create localized disruptions in the crystal lattice that scatter heat-carrying phonons while having minimal impact on electron transport, effectively reducing thermal conductivity without compromising electrical properties
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 new materials exhibit excellent thermoelectric conversion performance, potentially replacing or complementing existing materials, with improved ZT values and thermal conductivity, enhancing energy conversion efficiency.
Implementation Method 1
For example, for the thermoelectric conversion power generation, a temperature difference is applied to the thermoelectric conversion element to generate thermoelectromotive force, and then the thermoelectromotive force is used to convert thermal energy into electric energy.
Implementation Method 2
it provides methods for producing thermoelectric conversion materials expressed by the formula 1 by heating mixtures of Bi2O3, Bi, Cu, Te, and at least one selected from the group consisting of elemental Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Tl, As and Sb, or their oxides. In the method according to the present invention, the sintering process is preferably executed at temperatures of 400 to 570° C.
Data Source
AI summary
Thermoelectric conversion materials, expressed by the following formula: Bi1-xMxCu1-wOa-yQ1yTeb-zQ2z. Here, M is at least one element selected from the group consisting of Ba, Sr, Ca, Mg, Cs, K, Na, Cd, Hg, Sn, Pb, Mn, Ga, In, Tl, As and Sb; Q1 and Q2 are at least one element selected from the group consisting of S, Se, As and Sb; x, y, z, w, a, and b are 0≦x<1, 0<w<1, 0.2<a<4, 0≦y<4, 0.2<b<4, 0≦z<4 and x+y+z>0. These thermoelectric conversion materials may be used for thermoelectric conversion elements, where they may replace thermoelectric conversion materials in common use, or be used along with thermoelectric conversion materials in common use.