【作者】 陈俊；

【导师】 左如忠；

【作者基本信息】 合肥工业大学 ， 材料工程（专业学位）， 2021， 硕士

【摘要】 铌酸钠陶瓷（NaNbO₃:NN）作为一种典型的无铅反铁电（AFE）陶瓷,具备丰富的温度诱导相变过程。通过组成设计来调控其相结构,可以获得优异的机电性能。之前对NN的研究主要集中在相结构的演变及其应变特性,对于NN反铁电的储能应用研究较少。本文以铌酸钠为基体,通过组成设计调控NN的相结构演变,从而获得了良好的铁电、压电性能。同时,通过众多测试手段,深入的探讨了相结构对其储能性能和压电性能影响的内在机理。全文主要内容如下:（1）以NN为基体,通过A/B复合掺杂的方式向其中加入Na_0.5La_0.5TiO₃（LNT）合成（1-x）NN-x LNT（NLNT_x）固溶体陶瓷。La³⁺和Ti⁴⁺的复合掺杂不但有效的稳定了NN中的高温AFE R相,也诱发了明显的介电弛豫行为。结果表明,在x=0.16-0.2的组成范围内,陶瓷的储能性能得到了极大的提升。并在弛豫反铁电NLNT_0.18中掺入烧结助剂,掺杂烧结助剂后,由于晶粒尺寸减小,电阻率提高,介电损耗降低,击穿场强提高,储能性能进一步提高。HR-TEM和原位拉曼光谱分析证明了APNRs的存在和其在电场下的快速极化响应以及由此带来的高E_A-F～30 k V/mm,为本研究取得的优异储能性能提供了良好的理论基础。（2）以0.85NN-0.15LNT为基体,采用适量的Na SbO₃（NS）取代其中的NN,制备了新的NN-LNT-NS三元体系。结果表明,Sb离子的加入降低了B位离子的平均极化率,从而起到了稳定NN中AFE相的效果,同时Sb离子的加入也起到了降低陶瓷极化滞后的效果,极大的提升了陶瓷的储能效率。同样对NN-0.15LNT-0.03NS进行烧结优化,从而进一步提升其储能性能,最终获得了W_rec～6.05 J/cm³和η～80.4%的优异储能性能。并测量了其变温和变频的P-E曲线,通过计算发现该陶瓷具备良好的温度和频率稳定性,为陶瓷的实际应用提供了良好的基础。（3）通过固相反应法制备了LiNbO₃（LN）和NN的二元固溶体（1-x）NN-x LN陶瓷。结果表明LN的加入稳定了NN中的铁电相,并将纯NN中低温的铁电N相调制到室温。其室温结构随着LN的加入逐渐由正交（O）反铁电P相转变为正交铁电Q相最后再由Q相向三方（R）铁电N相转变。并且在x=0.12时获得了R相和O相的多晶型相界,从而获得了优异的电学性能。同时还通过变温拉曼的方式验证了高温四方相（T）的存在,并给出了NN-LN二元体系相图,为后期的进一步调控提供了结构基础。更多还原

【Abstract】 NaNbO₃（NN）,as a typical lead-free antiferroelectric（AFE）ceramics,have abundant temperature-induced phase transition process.By adjusting the phase structure through composition design,rich electromechanical properties can be obtained.Previous studies mainly focused on the evolution of its phase structure and its strain characteristics,while there were few studies on the application of energy storage.In this paper,with NN as the matrix,the phase structure evolution of NN is controlled by composition design,so as to obtain good ferroelectric and piezoelectric properties.At the same time,the internal mechanism of the effect of the phase structure on the energy storage performance and piezoelectric performance was deeply discussed by many testing methods.The main contents are as follows:（1）The complex substitution of La³⁺and Ti⁴⁺in NN was found to not only effectively stabilize high-temperature AFE R phase,but also induce obvious dielectric relaxor behavior.As a result,obviously enhanced energy-storage properties can be obtained in the composition range of x=0.16～0.20.In combination with the improvement of E_Bvalues of relaxor antiferroelectric NLNT_0.18 as a result of reduced grain size,enhanced resistivity and declined dielectric loss after doping sintering aids,energy-storage properties were further improved.The analysis of HR-TEM and in-situ Raman spectra demonstrates the existence and rapid field-polarization response of APNRs,as well as the resulting high E_AF value up to 30 k V/mm,providing a good understanding of the achievement of excellent energy-storage properties in this work.（2）A new NN-LNT-NS ternary system was prepared by using 0.85NN-0.15LNT as matrix and replacing NN with appropriate amount of Na SbO₃（NS）.the average polarizability of B-site ions reduces by addition of Sb ion,thus stabilizing the AFE phase in NN.At the same time,the addition of Sb ion also reduces the polarization hysteresis of ceramics,which greatly improves the energy storage efficiency（η）of ceramics.The energy storage performance of NN-0.15LNT-0.03NS was further improved by doping sintering aids.Finally,the excellent energy storage performance of W_rec～6.05 J/cm³ andη～80.4%was obtained.And measured the P-E loops in the different temperature and frequency,respectively.The results show that the ceramic has good stability of temperature and frequency,which provides a good foundation for the practical application.（3）LiNbO₃（LN）and NN binary solid solution（1-x）NN-x LN ceramics were prepared by solid-state reaction method.The results show that the addition of LN stabilizes the ferroelectric phase in NN and modulates the low temperature ferroelectric N phase to room temperature.With the addition of LN,the room-temperature phase structure changed from orthorhombic anti-ferroelectric P phase to orthorhombic（O）ferroelectric Q phase and then to rhombohedral（R）ferroelectric N phase.And the excellent electrical properties are obtained at R-O phase boundaries at x=0.12.At the same time,the existence of high temperature T phase was verified by Raman spectra,and the phase diagram of NN-LN binary system was draw,it provides a structural basis for further study.更多还原