聚对苯撑/LiNi0.5Fe2O4纳米复合热电材料的制备及其性能研究

本文以流变相反应法原位合成了聚对苯撑/LiNi_0.5Fe₂O₄纳米复合热电材料,并对其热电性能进行表征,研究了放电等离子烧结时保温时间对其热电性能的影响.结果发现,复合材料铁氧体颗粒粒径为100---300nm,其外部被一层聚对苯撑膜包覆.电子在Fe²⁺和Fe³⁺之间的跳跃机理在铁氧体电导中占主导作用,因此聚对苯撑/LiNi_0.5Fe₂O₄复合材料具有n型导电特性.随着保温时间增加,复合材料电导率基本不变,但热导率逐渐增大且Seebeck系数逐渐减小,导致热电优值系数降低.由于结合了有机物高电导率和低热导率以及无机材料高赛贝克系数的优点,所制备的复合材料热电性能较单一材料有较大提高.

Study on the preparation and properties of polyparaphenylene/LiNi0.5Fe2O4 anocomposite thermoelectric materials

Polyparaphenylene/LiNi-ferrite nanocomposites are prepared by a novel rheological phase reaction method. The thermoelectric properties of the as-prepared nanocomposites are characterized and the effect of spark plasma sintering (SPS) conditions is investigated. The TEM images show that the size of LiNi-ferrite is around 100---300 nm and the polyparaphenylene has diffused boundaries outside it. The negative value of Seebeck coefficient confirms the n-type conduction, and the n-type conduction is attributed to hopping of electrons from Fe²⁺ to Fe³⁺ ions. It is found that the electrical conductivity of nanocomposite does not change with sintering time whereas the Seebeck coefficient decreases and thermal conductivity increases with sintering time. Therefore the figure of merit decreases. Because of the high electrical conductivity and low thermal conductivity of organic material and high Seebeck coefficient of inorganic material, the figure of merit of nanocomposites is improved.