Control of non-linear self-localization phenomena of strongly coupling charge carriersin LiNb_(1-x)Ta_xO_3 (LNT) - solid solutions

该项目是“极性氧化物中周期性低维缺陷结构”研究组的一部分，该研究组致力于利用锂铌酸盐-钽酸锂（LiNb_（1-x）Ta_x）O_3，LNT）模型系统研究缺陷结构、电子和离子输运以及机电性质之间的相关性。该子项目的重点是强耦合电荷载流子与（i）固溶体系统的结构，原子特性，（ii）铁电畴壁的介电和结构特性，以及（iii）高温下离子扩散的传输特性的相互作用。因此，该项目旨在解决一般介电、氧化物固态材料中结构、电子和离子性质在自定位机制中的作用问题。特别是对于固溶体系统LNT，预计随着知识的扩展，可以通过调整组成，通过域结构和温度来定制控制电荷载流子的自定位的可能性。从面向应用的角度来看，例如非线性光子学或纳米光电子学，这与广泛控制（非）线性光学和电子特性的可能性问题有关。从方法学的观点来看，实现这一目标需要：（a）在亚皮秒至秒级的时间尺度上系统地应用紫外和可见光谱范围内的非线性光学、时间分辨光谱学的既定方法;（B）通过在微米尺度上进行空间分辨研究来扩展这些方法;（c）在室温以上的温度下应用这些方法。这与非线性光学宽视场和共焦显微镜与激发扫描光谱学的相关组合以及具有可控氧含量的温度单元的安装有关。实验结果上LNT晶体的不同组成和掺杂，铁电单畴或周期性极化晶体样品，将再现与数值模型计算的动力学的自定位，运输和复合过程中的介电环境的组成梯度，扩展的声子谱，晶格缺陷，域壁和离子扩散。通过与原子模型计算以及统计输运模型的比较，将开发特定材料，实验和非线性光学或电子参数之间的相关性。该项目的最后与非线性光学，电子和机电性能的控制可能性的基础上的自定位的电荷载体的识别。

The proposal is part of the research group 'Periodic low-dimensional defect structures in polar oxides', which is dedicated to the correlation of defect structure, electron and ion transport and electromechanical properties using the model system lithium niobate-lithium tantalate (LiNb_(1-x)Ta_x)O_3, LNT). The focus of this subproject is the interaction of strongly coupling charge carriers with (i) the structural, atomistic properties of the solid solution system, (ii) the dielectric and structural properties of ferroelectric domain walls, and (iii) the transport properties of ionic diffusion at elevated temperatures. Thus, the project aims to address the question of the role of structural, electronic and ionic properties in self-localization mechanisms in dielectric, oxide solid state materials in general. Specifically for the solid solution system LNT, it is expected that with the extended knowledge, possibilities for a tailored control of the self-localization of charge carriers by adjusting the composition, by domain structuring and temperature can be worked out. From an application-oriented point of view, e.g. non-linear photonics or nano-optoelectronics, this is connected with the question of possibilities for extensive control of (non-)linear optical and electronic properties. From a methodological point of view, the processing of this objective requires (a) the systematic application of established methods of nonlinear optical, time-resolved spectroscopy in the ultraviolet and visible spectral range on time scales from sub-picoseconds to the second range, (b) their extension by the aspect of spatially resolved studies on the micrometer length scale and (c) their application at temperatures above room temperature. This is associated with the correlative combination of nonlinear optical wide-field and confocal microscopy with excitation-scan spectroscopy and the installation of a temperature cell with a controllable oxygen content. The experimental results on LNT crystals of different composition and doping, ferroelectrically monodomain or periodically poled crystal samples, will be reproduced with numerical model calculations on the dynamics of self-localization, transport and recombination processes in the dielectric environment with composition gradients, extended phonon spectrum, lattice defects, domain walls and ionic diffusion. By comparison with atomistic model calculations as well as statistical transport models a correlation between material-specific, experimental and nonlinear optical or electronic parameters will be developed. The project ends with the identification of control possibilities of nonlinear optical, electronic and electromechanical properties based on the self-localization of charge carriers.