【作者】 厉英；

【导师】 姜茂发；

【作者基本信息】 东北大学 ， 钢铁冶金， 2006， 博士

【摘要】 热电材料是一种将热能和电能直接转换的功能材料。由热电材料制成的热电器件具有很多独特的优点，在少数科技尖端领域已获得成功的应用。本文综合评述了国内外热电材料研究进展，发现氧化物热电材料具有使用温度高、抗氧化、无污染、制备简单、使用寿命长等优点，成为具有研究潜力和应用价值的新型热电候选材料。本论文选择NaCo₂O₄氧化物热电材料作为研究对象，通过掺杂及各种合成，研究提高NaCo₂O₄基材料的热电优值。 本文分别采用固相反应法和首次应用柠檬酸溶胶—凝胶法对NaCo₂O₄以及Na位掺杂K、Ca、Sr、Ce试样进行了制备研究，采用热压烧结法和冷压烧结法制备Co位掺杂Ti，Ni，Cr的NaCo₂O₄试样，并对试样进行X射线衍射分析及电导率、Seebeck系数等测定，同时进一步分析研究了掺杂不同元素、不同掺杂量、不同制备方法对热电性能的影响，提出最佳的掺杂元素和最佳掺杂量。 本论文的主要研究成果如下： （1） 采用固相反应法和柠檬酸溶胶—凝胶法均可以获得纯度较高的NaCo₂O₄，并且采用这两种方法都可以使K，Ca，Sr掺杂入NaCo₂O₄晶格中。采用柠檬酸溶胶—凝胶法制备的掺Sr、Ca试样的功率因子高于固相反应法。 （2） NaCo₂O₄试样掺杂K，Ca，Sr均能提高材料的功率因子，掺杂Ce使NaCo₂O₄的功率因子降低。采用柠檬酸溶胶—凝胶法按照化学式(Na_0.9Sr_0.1)_1.6Co₂O₄制备的试样的功率因子最大，其值为2.26×10^-4W·m^-1·K^-2，比掺杂前NaCo₂O₄试样的功率因子提高了49.7％。因此对NaCo₂O₄的Na位掺杂研究获得最佳掺杂元素为Sr，最佳掺杂量为0.1。 （3） 研究结果表明不同制备方法对材料电阻率影响显著，与冷压烧结法相比较，热压烧结法制备试样的电阻率较小。实验发现Cr的掺杂有利于电导率的提高，无助于Seebeck系数的提高，而掺杂Ni、Ti使材料的电导率降更多还原

【Abstract】 Thermoelectric material is a kind of functional material converting heat energy directly to electric energy. Devices made of thermoelectric material have many special advantages, and have been successfully used in a few acmes of science and technology. In the present work, the development in thermoelectric materials were reviewed and discussed. Recently, Oxide thermoelectric materials were found to have high working temperature, oxidation-resistant, no pollution, simple preparation, long life, and have become new candidate materials with a potential to study and applying values. In this paper, Oxide NaCo₂O₄ has been selected as this study due to very good thermoelectric performance. A new series of oxides were synthesized by the substitution and their thermoelectric properties were investigated.In this work, NaCo₂O+4 doped with K, Ca, Sr, Ce in Na position by solid state reaction and sol-gel methods in the first time, and NaCo₂O₄ doped by Ti, Ni, Cr in Co position by hot-pressed sinter and cool-pressed sinter were prepared, and electrical conductivity and Seebeck coefficients of the materials were measured, as well as the effects of doping elements, doping amount and preparing methods were also investigated to optimize the preparation of the materials.The main achievements of the work are followings:（1） High purity NaCo₂O₄ doped with K, Ca, Sr was prepared by both solid state reaction and sol-gel method. Power factor of NaCo₂O₄ prepared by sol-gel method is higher than that by solid-state reaction method.（2） Power factor of NaCo₂O₄ was increased by doping K, Ca and Sr and decreased by Ce. Power factor of (Na_0.9Sr_0.1)_1.6Co₂O₄ prepared by sol-gel method is 2.26×10^-4W·m^-1·K^-2 and the highest, increased 49.7% compared with that before更多还原