NaNbO3的溶胶-凝胶制备与放电等离子烧结

Sol-gel Synthesis of NaNbO3 Nanopowder and Its Densificationby Spark Plasma Sintering

摘要:

铌酸钠陶瓷具有反铁电特征和复杂的相变序列,在介电储能与压电器件领域潜在重要应用。但是,传统陶瓷工艺难以制备均匀致密的铌酸钠陶瓷,影响其性能优化。本文将溶胶-凝胶粉体制备技术与放电等离子烧结技术相结合,构建铌酸钠细晶陶瓷。结果显示,采用水基溶胶-凝胶法,可合成高活性,平均粒径仅40 nm的纯钙钛矿相纳米粉体,以其为前驱体进一步进行放电等离子烧结可获得平均粒径1 ~ 2 μm的致密陶瓷。电学测试证明铌酸钠陶瓷中缺陷偶极子可以诱导反铁电—铁电相变,室温下材料介电常数具有优良的频率稳定性,且介电损耗仅为0.018(1 kHz)。本工作不仅获得在无铅铁电器件领域潜在应用价值的铌酸钠细晶陶瓷,而且相关技术路线设计为制备其它铌酸盐功能陶瓷提供新的工艺思路。

Abstract:

NaNbO3, one of typical antiferroelectric niobates with a complicated sequence of phase transition, has attracted much attention recently due to its potential application in the energy storage and piezoelectric devices. However, for the traditional ceramic process, it is difficult to prepare uniform and dense NaNbO3 ceramics, affecting its performance optimization. In this work, the sol-gel method in combination with spark plasma sintering (SPS) has been applied to build NaNbO3 fine-grained ceramics. The results revealed that perovskite type NaNbO3 nano-powders with mean size of 40 nm can be synthesized by using an aqueous sol-gel route. Subsequently, using the resulted NaNbO3 nano-powders as precursors, the dense ceramics with mean grain size of 1-2 μm were obtained by SPS method. The electrical measurement evidenced that the defect dipoles play the roles of assisting antiferroelectric to ferroelectric (AFE-FE) phase transition. Moreover, the dielectric constant exhibits good frequency stability and the loss tangent was as low as 0.018 (1 kHz). Our work not only provided the dense NaNbO3 ceramics with potential application in new generational lead-free ferroelectric devices, but also developed a new route to construct fine-grained ceramics, which can be applied to prepare other niobates system.