Collaborative Research: From Synthesis, Local and Electronic Structures, to Optical and Scintillating Properties of Lanthanoid Hafnate Nanoparticles

许多化学物质具有发射辐射的性质，称为发光，这在发光应用中很有用。由于稀土离子在光产生和放大方面的独特光学性质，它在我们的日常生活中起着至关重要的作用。除了激光物理学，我们日常生活中熟悉的其他应用还包括照明、显示器、光学电信、夜视、安全油墨、伪造标签、发光涂层、医学成像、医疗诊断和机场安检。为了制造廉价、广泛、持久的发光或光子器件，从技术和经济两方面的需要都需要新的和更有效的发光材料。德克萨斯大学里奥格兰德山谷的毛元冰博士和路易斯安那州立大学的詹姆斯·多尔曼博士正在通过开发新的制备方法来制造发光增强的金属氧化物纳米颗粒。利用各种技术，并与橡树岭国家实验室的科学家合作，研究小组正在研究他们可靠的合成方法如何使这些纳米颗粒超小，形状和大小均匀，比人类头发的直径小1000多倍。该团队还研究了这些纳米颗粒的大小、形状、结构、组成和发光性能之间的关系。在这个项目中获得的基本认识有助于未来新型发光纳米材料、光子器件和纳米粒子合成方法的设计。毛博士和多曼斯博士的研究对很多层次的学生都很有吸引力，他们强调让未被充分代表的学生担任研究助理。研究小组在全校范围内推出了一系列研讨会和几个新的课程单元。通过这些活动，毛博士和。多曼直接在不同的人口群体中提高对纳米科学和光电材料的认识和倡导，以此来改善社区、国民经济和环境。在这个研究项目中，德克萨斯大学格兰德河谷大学(UTRGV)的毛元冰博士和路易斯安那州立大学(LSU)的James Dorman博士得到了大分子、超分子和纳米化学(MSN)计划的支持，以开发可靠的合成工艺，了解生长机制，研究尺寸效应，并将晶体、局部和电子结构与这些稀土系纳米荧光粉的光学和闪烁特性相关联。采用非原位和原位技术研究了影响纳米Ln2Hf2O7颗粒大小和结构参数的合成参数。基于所获得的结果，发展了这些纳米粒子的生长机理，以用于基于应用规范的发光纳米粒子的定向设计。接下来，通过拉曼光谱、同步辐射X射线和中子衍射、X射线吸收、发射和光电子能谱、光致发光和辐射发光等互补技术，探讨了这些纳米粒子的晶体结构、局域结构和电子结构与其发光性能之间的关系。此外，本研究还为Ln2Hf2O7化合物在各种设备中的适当应用提供了一般指导，如高温固体氧化物燃料电池中的固体电解质、热障涂层和核废料存储。毛博士让高中生、本科生和研究生参与他的研究，重点是代表性不足的学生，并在大学范围内推出了一系列研讨会和新的课程模块，突出了他的团队的研究主题。他和路易斯安那州立大学(LSU)的詹姆斯·多曼博士向所有年龄段的学生交流科学，直接提高不同人口群体对纳米科学和光电材料的认识和倡导，以此来改善社区、国民经济和环境。这些活动还为代表性不足的学生建立了强大的渠道，并使UTRGV和路易斯安那州立大学之间富有成效的师生交流项目取得了成果。

Many chemical substances have the property of emitting radiation, called luminescence, which is useful in light-emitting applications. Lanthanide luminescence plays a vital role in our daily life due to the unique optical properties of these ions with respect to light generation and amplification. Extending from laser physics, other familiar applications in our regular life include lighting, displays, optical telecommunications, night vision, security inks, counterfeiting tags, luminescent coatings, medical imaging, medical diagnostics, and airport security checks. New and more effective luminescent materials are desirable from both a technological and an economic necessity in order to make cheap, widely available, and long-lasting light emitting, or photonic, devices. Dr. Yuanbing Mao of the University of Texas Rio Grande Valley and Dr. James Dorman of Louisiana State University are making metal oxide nanoparticles with increased luminescence by developing new preparation methods. Using various techniques and in collaboration with scientists at Oak Ridge National Laboratory, the research team is figuring out how their reliable synthesis methods make these nanoparticles ultra-small and uniformly shaped and sized, at more than 1000 times smaller than the diameter of a human hair. The team also studies the relationship between the size, shape, structure, composition, and luminescence performance of these nanoparticles. The fundamental understanding gained in this project helps the future design of new luminescent nanomaterials, photonic devices, and nanoparticle synthesis methods. Dr. Mao's and Dr. Dormans's research is attractive to students at many levels, emphasizing the involvement of underrepresented students as research assistants. The research team has introduced a university-wide seminar series and several new course modules. Through these activities, Drs. Mao and. Dorman directly raise awareness and advocacy for nanoscience and optoelectronic materials among varied demographic groups as a way to improve the community, the national economy, and the environment. The partnership focuses on building a strong pipeline for underrepresented students and enabling fruitful student-faculty exchange programs between the two universities.In this research program, Dr. Yuanbing Mao of the University of Texas Rio Grande Valley (UTRGV) and Dr. James Dorman of Louisiana State University (LSU) are supported by the Macromolecular, Supramolecular and Nanochemistry (MSN) Program to develop a reliable synthetic process, understandthe growth mechanism, investigate the size effects, and correlate the crystal, local and electronic structures with the optical and scintillating properties of these lanthanoid hafnate nanophosphors. Ex situ and in situ techniques are used to elucidate the synthetic parameters which determine the particle size and structural parameters for these Ln2Hf2O7 nanoparticles. Based on the obtained results, growth mechanisms of these nanoparticles are developed for directed design of luminescent nanoparticles based on application specifications. Next, the relationship between the crystal, local, and electronic structures of these nanoparticles and their luminescent properties is probed via complementary techniques, such as Raman spectroscopy, synchrotron X-ray and neutron diffractions, X-ray absorption, emission and photoelectron spectroscopies, photoluminescence, and radioluminescence. In addition, this study provides general guidance for proper selection of Ln2Hf2O7 compounds for suitable applications in a wide variety of devices, such as solid electrolytes in high temperature solid oxide fuel cells, thermal barrier coatings, and nuclear waste storage. Dr. Mao involves high school, undergraduate, and graduate students, with an emphasis on underrepresented students, in his research, and has introduced a university-wide seminar series and new course modules which highlight the topics of his team?'research. He and Dr. James Dorman of the Louisiana State University (LSU) communicate science to students at all age levels, directly raising awareness and advocacy for nanoscience and optoelectronic materials among varied demographic groups as a way to improve the community, the national economy, and the environment. The activities also build a strong pipeline for underrepresented students and enable fruitful student-faculty exchange programs between UTRGV and LSU.