Solid-State Oxides and Oxide-Fluorides

摘要高效非线性光学材料是电光应用中必不可少的波导材料。这些材料用于超快激光光谱学，最近，用于产生纳米光刻应用的紫外激光。目前NLO材料领域的研究和工程活动通常涉及NLO晶体的合成；然而，需要研究如何设计NLO材料以及为什么材料表现出特定的NLO响应。在探索创造新型NLO材料的基本驱动因素的同时，将进行大型（约1立方厘米）单晶的研究，以定量了解光与NLO材料的相互作用。同时从事当地教育、教学、指导和领导工作的研究生和博士后对基本原理的分析，将促进科学进步，促进这一重要技术领域的商业扩张。新兴技术需要高性能非线性光学（NLO）材料在微观和宏观水平上表现出增强的光学性能。晶体结构的合理设计，特别是非中心对称材料，以及如何针对极性、极性手性和手性结构，是晶体工程中一个不断发展的主题。一类潜在的高性能NLO无机材料，固态氧化物-氟化物，已经被确定。这些研究表明，i)与纯氧化物化合物相比，使用含早期过渡金属的氟配体增强了二阶扬-泰勒畸变，ii)使用极性碱性构建单元可以促进非中心对称材料的合成，iii)含有两个独立阴离子构建单元的化合物的合成可能会产生非中心对称化合物。这些材料包含了大量的新型固体，具有与压电性、热释电性、铁电性和二次谐波产生（SHG）相关的特性。我们将研究导致NLO材料高、低或零非线性的结构-性质关系。最后，大晶体的生长（约为一立方厘米）允许通过测量NLO张量和相位匹配性以及其他感兴趣的特性（如压电性）进行详细分析。合成的材料在弛豫铁电体和非线性光学领域具有潜在的应用前景。这些材料将具有高损伤阈值和制造适合光学用途和技术应用的大型单晶的潜力。本项目由材料研究部固态与材料化学项目资助。

Non-Technical AbstractHighly-efficient non-linear optical (NLO) materials are essential to act as waveguides for electrooptic applications. Such materials are used in ultrafast laser spectroscopy and, more recently, to generate ultraviolet laser light for nanolithographic applications. Current research and engineering activities in the field of NLO materials typically concern synthesis of NLO crystals; however, research is needed for understanding how to design NLO materials and why materials exhibit a particular NLO response. While exploring the fundamental driving factors for creation of new NLO materials, research will be performed to grow large (on the order of one cubic centimeter) single crystals to allow a quantitative understanding of the interaction of light with the NLO material. These analyses of basic principles by graduate students and postdoctoral associates -- who are also engaged in local education, teaching, mentoring, and leadership -- will enhance scientific progress and promote commercial expansion of this technologically important field.Technical AbstractEmerging technologies require high-performance nonlinear optical (NLO) materials that exhibit enhanced optical properties at the microscopic and macroscopic level. The rational design of crystal structures, in particular noncentrosymmetric materials, and how to target polar, polar-chiral, and chiral structures, is an ongoing theme in crystal engineering. A new class of potentially high performance NLO inorganic materials, solid-state oxide-fluorides, has been identified. These studies demonstrate that i) the use of fluoride ligands with early-transition metals enhances the second-order Jahn-Teller distortion in comparison to pure oxide compounds, ii) the synthesis of noncentrosymmetric materials can be promoted with the use of polar basic-building units, and iii) the synthesis of compounds that contain two separate anionic building units is likely to result in a noncentrosymmetric compound. These materials comprise a large and new class of solids with properties associated with piezoelectricity, pyroelectricity, ferroelectricity and second harmonic generation (SHG). The structure-property relationships that give rise to high, low, or null nonlinearities of the NLO materials will be examined. Finally, the growth of large crystals (on the order of one cubic centimeter) allows detailed analysis with measurements of the NLO tensor and phase-matchability properties, and other properties of interest such as piezoelectricity. The materials synthesized will have potential use in relaxor ferroelectrics and non-linear optics. These materials will have a high damage threshold and the potential to fabricate large, single crystals suitable for optical use and technical applications. The project is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research.