Research On Preparation And Properties Of Pb₂Sb₆Te₁₁ Under High Temperature And High Pressure

Thermoelectric materials is a functional materials of thermal energy turn into electrical energy directly. Requirements of high-performance thermoelectric materials with high conductivity and the Seebeck coefficient, at the same time have a lower thermal conductivity. The efficiency of a thermoelectric device is governed by the thermoelectric figure of merit, zT, of the component materials,defined as: where S is the Seebeck coefficient,σthe electrical conductivity, andκthe thermal conductivity.Solid-state thermoelectric device have many advantages:small, chape, lighe-weight,the work do not use any other matter or parts, and work with no noise,no pollution,such as the excellent performance.Therefore, thermoelectric materials is a functional materials with a very broad application prospects. Access to high-quality thermoelectric materials become people's tireless pursuit.Reduce the thermal conductivity of materials is an effective way to improve the thermoelectric properties. Recently, scientists have discovered the structure of superlattice materials can effectively reduce the thermal conductivity.The Vacuum Sintering of Pb₂Sb₆Te₁₁ material found that the material will be divided into PbTe and Sb2Te3 under the condition Rapid cooling, similar to the formation of a superlattice structure formed in material.The structure can reduce the thermal conductivity effectively. But there is not acquired the report of The synthesis of Pb₂Sb₆Te₁₁ under high temperature and high pressure.This work, utilize the advantages of composite materials under high temperature and high pressure, Exploration the synthesis of high-purity Pb₂Sb₆Te₁₁ material under high temperature and high pressure at 4GPa pressure and 700 1300 K the temperature. And the use of XRD and EPMA analysis, etc. Studied the Impact of different temperature to the composition of Pb₂Sb₆Te₁₁ under the pressure condition. To further lay the foundation for the in-depth study.Through high temperature and high pressure experiments, we acquired a relatively high purity materials Pb₂Sb₆Te₁₁. The experimental results show that high purity Pb₂Sb₆Te₁₁ have stringent requirements of temperature,only when the temperature is about 876K, we will be able to have a relatively pure Pb₂Sb₆Te₁₁, the phenomenon occurs when temperature deviate from the require. Resistivity test results show that we can have a lower resistivity of the material synthesized when the temperature escalate. The test of EPMA shows that the decomposition of material will have different stripe-shaped regional. Divided into three regional, Rich PbTe, Rich Sb2Te3 and Rich Pb₂Sb₆Te₁₁ areas.The structure Showed similar morphology superlattice,and the components will change in the temperature change. Contrast was found that when the synthesis temperature was 892K the stripe decomposition have most evenly spaced around about 1μm. Superlattice structure can effectively reduce the material's thermal conductivity.However, there is no obtained the report about high temperature and high pressure on the structure of materials, this paper will be the future more in-depth research has laid a good foundation.