Artificial multi-layer structure strontium titanate thermoelectric material and preparation method thereof

Abstract

The invention relates to the field of composite and thermoelectric material, and provides a preparation method of an artificial multi-layer structure strontium titanate thermoelectric material. The proportion of matrix and embedded phase in the designed structure and the number of stacked surfaces are adjusted to ensure that the material has both high electrical conductivity and low thermal conductivity. The preparation method comprises the following steps: firstly, cubic phase niobium-doped strontium titanate is prepared as a matrix conductive phase by a solid state method under the anoxic condition; then R-P-structure lamellar strontium titanate is prepared as the embedded phase by using a molten salt method; and then a green body is prepared by the cubic phase niobium-doped strontium titanate and the R-P-structure lamellar strontium titanate according to different mas ratios through the curtain coating and other processes and then sintered by the sps method so that the artificial multilayer structure strontium titanate thermoelectric material is obtained. The material has a first-order phonon scattering mechanism formed by the interface between the embedded phase and the matrix,a second-order phonon scattering mechanism formed by directional arrangement of the embedded phase in the matrix and a third-order phonon scattering mechanism formed by a plurality of sub-layer interfaces. The material is enabled to have both high electrical conductivity and low thermal conductivity so as to provide a new idea for improving the thermoelectric performance of the material.

Description

technical field [0001] The invention belongs to the field of functional composite materials and thermoelectric materials, and relates to an artificial multilayer strontium titanate thermoelectric material and a preparation method thereof. Background technique [0002] Thermoelectric materials can convert heat and electricity into each other, and are clean energy materials with broad application prospects. The efficiency of thermoelectric materials in converting heat and electricity into each other is measured by thermoelectric figure of merit (ZT). A material with a larger ZT value has a higher thermoelectric conversion efficiency. [0003] [0004] Wherein, S is a Seebeck coefficient, and different types of materials have different seebeck coefficient ranges. σ is electrical conductivity, λ is thermal conductivity, and T is absolute temperature. [0005] In order to obtain a higher ZT value, the material needs to have high Seebeck coefficient and electrical conductivi...

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Problems solved by technology

But in fact, there is a complex coupling relationship between these three properties, especially between thermal conductivity and electrical conductivity. Generally, as the doping concentration increases, electrical conductivity and thermal conductivity will increase synchronously. In the formula of thermoelectric figure of merit, thermal conductivity and electrical conductivity are divided into numerator and denominator positions, which leads to the fact that the thermoelectric figure of merit cannot be improved

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