Room-Temperature Liquid Phase Synthesis of BiSbTe Nanocompounds
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Solution Overview
Problem
Existing methods for synthesizing BixSb2-xTe3 thermoelectric nanocompounds often result in high thermal conductivity due to particle growth during heat treatment, limiting the improvement of thermoelectric figure of merit.
Innovation Solution
A method involving liquid phase reduction at room temperature to form BixSb2-xTe3 nanoparticles without additional heat treatment, using Bi, Sb, and Te precursors in a solvent, followed by mixing with a base aqueous solution, adding a reducing agent, aging, and filtering to produce evenly sized nanoparticles with reduced thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat treatment is applied to eliminate chemical additives, then purity of the nanocompound is improved, but particle size increases and thermal conductivity increases
Solution Approach 1:
The patent extracts and removes chemical additives through washing with solvents (water, alcohol, acetone) instead of using heat treatment. This extraction process eliminates the harmful effect of heat-induced particle growth while maintaining additive removal, thereby preserving nanoparticle size and reducing thermal conductivity.
Solution Approach 2:
The patent replaces the thermal processing system with a chemical washing system. Instead of using heat (thermal energy) to remove additives, the invention uses solvent washing (chemical mechanism) to achieve the same purification goal without the adverse thermal effects on particle size.
2Stability of the object's composition
If particle size is reduced to nano-scale, then thermal conductivity is reduced, but electrical conductivity decreases
Solution Approach 1:
The patent changes the compositional parameters by incorporating multiple elements (Bi, Sb, Te) in specific ratios and controlling the nanoparticle composition. This parameter optimization allows maintaining high electrical conductivity at nano-scale by adjusting the material composition to balance both electrical and thermal conductivity properties.
Solution Approach 2:
The patent creates a composite nanocompound structure with Bi, Sb, and Te elements. This composite approach allows combining the beneficial properties of different elements - Bi and Sb for electrical conductivity and Te for structural stability - achieving both low thermal conductivity and high electrical conductivity simultaneously.
3Productivity
If conventional synthesis methods are used, then thermoelectric materials can be produced, but high thermal conductivity results from micro-meter particle size
Solution Approach 1:
The patent performs preliminary actions by dissolving precursors in solvents and forming homogeneous solutions before synthesis. This preliminary preparation ensures uniform nucleation and growth of nanoparticles at controlled sizes, preventing micro-meter particle formation and ensuring low thermal conductivity from the outset.
Solution Approach 2:
The patent utilizes phase transitions during the synthesis process, controlling the transformation from dissolved precursor state to solid nanoparticle state. By controlling this phase transition through solvent evaporation and drying at low temperatures, the method produces nanoparticles instead of micro-meter particles, achieving low thermal conductivity while maintaining productivity.
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 method effectively synthesizes BixSb2-xTe3 nanocompounds with reduced thermal conductivity and improved thermoelectric figure of merit, making them suitable for thermoelectric modules without the need for high-temperature processing.
Implementation Method 1
preparing a BixSb2-xTe3 reactant by liquid phase reduction at room temperature after adding a reducing agent to the Bi—Sb—Te hydrate prepared in step 2) (step 3)
Implementation Method 2
Thermoelectric generation indicates the general technique to convert waste heat produced from everyday life and from a variety of industrial fields into electromotive force by using thermoelectric module. That is, it is the technique to convert thermal energy into electric energy by using Seebeck effect.
Data Source
AI summary
The present invention provides a method for synthesizing a BixSb2-xTe3 thermoelectric nanocompound (0<x<2), comprising the following steps: preparing a Bi—Sb—Te solution by adding Bi, Sb, and Te precursors to a solvent (step 1); preparing a Bi—Sb—Te hydrate by mixing the Bi—Sb—Te solution prepared in step 1) with a base aqueous solution (step 2); preparing a BixSb2-xTe3 reactant by liquid phase reduction at room temperature after adding a reducing agent to the Bi—Sb—Te hydrate prepared in step 2) (step 3); aging the BixSb2-xTe3 reactant prepared in step 3) (step 4); and preparing BixSb2-xTe3 nanoparticles by filtering and drying the BixSb2-xTe3 reactant aged in step 4) (step 5). The BixSb2-xTe3 thermoelectric nanocompound synthesized by the method of the present invention via liquid phase reduction is composed of regular nanoparticles since the method does not need any additional heat-treatment to eliminate chemical additives and prevents particles from being over-grown. Therefore, the BixSb2-xTe3 nanocompound particles are regular in size of 1˜150 nm and distributed evenly, so that thermal conductivity of the compound is reduced and thereafter thermoelectric figure of merit thereof can be improved.