Thermoelectric Element with Non-Stoichiometric Ax-cBy Composition
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Solution Overview
Problem
Thermoelectric conversion elements lack the ability to change the conductivity type of their compound semiconductor materials, limiting their application in temperature sensors and other uses.
Innovation Solution
A thermoelectric conversion element with a thermoelectric conversion material composed of a compound semiconductor represented by Ax-cBy, where x is smaller than the stoichiometric ratio, featuring a phase diagram with low, high, and coexisting temperature phases, allowing the conductivity type to change with temperature, thereby enhancing thermoelectric performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional thermoelectric conversion element uses a fixed composition compound semiconductor, then the device structure is simple and manufacturing is easy, but the conductivity type cannot be changed with temperature, limiting application in temperature sensors
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameter (stoichiometric ratio) of the compound semiconductor material. Specifically, it uses a composition Ax-cBy where x is smaller than the stoichiometric ratio, which enables the material to undergo conductivity type changes with temperature variations, thereby resolving the contradiction between adaptability and device complexity
Solution Approach 2:
The patent employs composite materials by creating a compound semiconductor with a specific non-stoichiometric composition (Ax-cBy). This composite approach allows the material to exhibit multiple phases (low temperature phase, high temperature phase, and coexisting phase) that enable conductivity type transformation, achieving both adaptability and controlled complexity
2Adaptability or versatility
If the thermoelectric conversion material uses a stoichiometric compound semiconductor, then the material structure is stable and easy to manufacture, but the Seebeck coefficient cannot be modified with temperature changes, reducing functionality in temperature sensing applications
Solution Approach 1:
The patent changes the composition parameter by using a non-stoichiometric ratio (Ax-cBy where x < stoichiometric ratio). This parameter modification enables the Seebeck coefficient to be modified with temperature changes, while the specific formulation maintains manufacturability by defining clear compositional boundaries
3Reliability
If a thermoelectric conversion element uses a single-phase compound semiconductor, then the material behavior is predictable and simple, but it cannot achieve the phase transitions necessary for conductivity type changes and enhanced thermoelectric performance
Solution Approach 1:
The patent uses composite materials with non-stoichiometric composition (Ax-cBy) that naturally form multiple phases (low temperature phase, high temperature phase, and coexisting phase). This composite structure enables phase transitions that improve thermoelectric conversion efficiency while the specific composition control keeps the complexity manageable
Solution Approach 2:
The patent exploits phase transitions by designing a material system that undergoes transitions between low temperature phase, high temperature phase, and coexisting phase. These phase transitions enable conductivity type changes and enhance thermoelectric performance, with the phase diagram providing a roadmap for controlling the transitions
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
Enables the reliable change of conductivity type in the compound semiconductor, improving thermoelectric conversion efficiency and allowing the element to be used in temperature sensors by modifying the Seebeck coefficient with temperature changes.
Implementation Method 1
heat is directly converted into electricity, so no extra waste is discharged during the conversion
Data Source
AI summary
A thermoelectric conversion element includes a thermoelectric conversion material portion having a compound semiconductor composed of first base material element A and second base material element B and represented by Ax-cBy with value of x being smaller by c with respect to a compound AxBy according to a stoichiometric ratio, a first electrode disposed in contact with the thermoelectric conversion material portion, and a second electrode disposed in contact with the thermoelectric conversion material portion and apart from the first electrode. An A-B phase diagram includes a first region corresponding to low temperature phase, second region corresponding to high temperature phase, and third region corresponding to coexisting phase, sandwiched between the low temperature phase and the high temperature phase, in which the low and high temperature phases coexist. A temperature at a boundary between the first region and the third region changes monotonically with a change in c.