摘要
铌酸钾钠(K0.5Na0.5NbO3,KNN)基铁电材料被认为是最有可能取代铅基铁电材料的无铅体系之一,但是较差的铁电性和温度稳定性限制了其应用.本文采用脉冲激光沉积技术,在Sr-TiO3(100)衬底上,以La0.07Ba0.93SnO3(LBSO)为底电极,成功外延生长了 Mn掺杂的K0.5Na0.5NbO3 无铅铁电薄膜(K0.5Na0.5NbO3-1wt.％MnO2,KNN-M),并系统研究了薄膜的结构,形貌,性能及相变行为.研究结果表明,KNN薄膜高质量外延,具有良好的铁电性能,电滞回线为饱和的矩形,在800 kV/cm的外加电场下,剩余极化值2Pr达到48.1 μC/cm2,矫顽电场2Ec达到214 kV/cm;室温下具有较高介电常数(717.56)和较低介电损耗(0.146);此外,薄膜还有着较高的Tc值(～405 ℃).以上结果说明,K0.5Na0.5NbO3-1wt.％MnO2薄膜作为取代铅基铁电薄膜的候选材料具有很大潜力.
Abstract
KNN-based(K0.5Na0.5NbO3)ferroelectric materials are considered one of the most promising lead-free systems to replace lead-based ferroelectric materials.However,their poor ferroelectricity and temperature stability limit their application.This article utilizes the pulsed laser deposition method with SrTiO3(100)as the substrate and La0.07Ba0.93SnO3(LBSO)as the bottom electrode to successfully epitaxially grow K0.5 Na0.5 NbO3 lead-free ferroelectric thin films with 1wt.％MnO2 addition(K0.5Na0.5NbO3-1wt.％MnO2,KNN-M).The phase structure,microstructure,electrical properties,and phase transition behavior of the thin films are systematically studied.The research results indicate that KNN thin films have high crystalline quality and a rectangular saturated hysteresis loop with 2Pr=48.1 pC/cm2,2Ec=214 kV/cm under an applied electric field of 800 kV/cm.At room temperature,they exhibit a high dielectric constant(717.56)and a low dielectric loss(0.146).Additionally,the films also have a high Tc value(～405 ℃).These results imply that K0.5Na0.5NbO3-1wt.％MnO2 thin films can be used as a candidate material to replace lead-based ferroelectric thin films.
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