稀土掺杂铁电纳米线的发光可调研究

Rare earth luminescent materials with tunable photoluminescence (PL) properties have widespread applications, such as laser mediums, optical waveguides and display, and possess important research interest in future. Our previous research results have shown that doped with rare earth ions, ferroelectric materials posses both good PL and ferroelectric propeties. But further understanding of the relationship between ferroelectric properties and PL is needed. Luminescence from the rare earth ions is very sensitive to the crystal-field. The unique crystal structure of ferroelectric materials provides us an opportunity to tuning PL by controlling the external electric field and strain in rare earth doped ferroelectric materials. However, the present study electric mainly focus on the tuning PL by external electric field in bulks. The goal of this project is to develop a fundamental understanding of the kinetic process how the luminescence changes with structural symmetry in rare earth doped ferroelectric nanowires, as well as the tuning effects by these two different external factors. Through the study of this proposal, we could not only obtain the physical mechanism in the process of the tuning of PL, but also the failure mechanism of the tuning of PL.Under this proposal, we may figure out some fundamental issues for the application in integrated optoelectronic devices based on rare earth doped low-dimentional ferroelectirc materials.

稀土发光可调材料在激光介质、光波导、显示器等方面具有巨大应用潜力，是今后重要的研究方向。我们前期的研究结果表明，稀土掺杂不仅改善了材料的铁电特性，还使材料具有优异的发光特性，然而关于铁电特性和发光之间的联系需要进一步研究。由于稀土离子的发光受晶体场的影响较大，铁电体独特的晶体结构使得在稀土掺杂铁电材料中，通过外加电场、应力等调控发光变得可能。但是，目前研究多偏重电场对发光的调控，且多局限于陶瓷块体。本项目拟采用外加电场和应力的方法，研究稀土掺杂发光铁电纳米线中，电场和应力对稀土离子光致发光的调控作用，以及尺寸效应带来的影响，并分析其中的发光动力学过程和失效机制，阐明外加电场、应力通过改变铁电材料的晶体场，从而影响稀土离子发光的具体物理过程，以及能量转移机制，为材料在光电功能集成器件等领域的应用奠定基础。

铁电材料作为一类重要的功能材料，在激光器、微电子、光电子和国防科技等领域有着广泛的应用。器件的小型化、多功能化、集成化一直是各种功能器件发展的趋势。铁电纳米线由于其独特的一维特性，使其具有特殊的铁电、压电、非线性光学等性质，在纳米发电机、非挥发性随机存储器、纳米光学等方面具有潜在的应用价值。项目利用溶胶-凝胶法、水热法等材料生长工艺，制备了稀土掺杂的铁电纳米线，通过反应时间、反应温度以及矿化剂的浓度的控制,来实现铁电纳米线的可控生长。弄清了稀土离子的掺杂浓度对材料的铁电、介电以及发光特性的影响，找到了最佳的掺杂浓度。在此基础上，重点研究了温度与材料发光的关系，并设计了基于稀土掺杂铁电材料的新型纳米温度计，在400K实现了0.0053K-1的灵敏度。在Na0.5Bi0.5TiO3铁电纳米线，我们观察到了非常强的二次谐波产生，重点研究了其产生机理，同时发现其具有非常低的波导损耗，当波导光为532纳米时，其损耗为0.01dB/μm。这表明Na0.5Bi0.5TiO3铁电纳米线在未来集成光电子系统中有潜在的应用价值。